WorldWideScience

Sample records for proposed clear skies

  1. Clear-sky classification procedures and models using a world-wide data-base

    International Nuclear Information System (INIS)

    Younes, S.; Muneer, T.

    2007-01-01

    Clear-sky data need to be extracted from all-sky measured solar-irradiance dataset, often by using algorithms that rely on other measured meteorological parameters. Current procedures for clear-sky data extraction have been examined and compared with each other to determine their reliability and location dependency. New clear-sky determination algorithms are proposed that are based on a combination of clearness index, diffuse ratio, cloud cover and Linke's turbidity limits. Various researchers have proposed clear-sky irradiance models that rely on synoptic parameters; four of these models, MRM, PRM, YRM and REST2 have been compared for six world-wide-locations. Based on a previously-developed comprehensive accuracy scoring method, the models MRM, REST2 and YRM were found to be of satisfactory performance in decreasing order. The so-called Page radiation model (PRM) was found to underestimate solar radiation, even though local turbidity data were provided for its operation

  2. Evaluation of Clear Sky Models for Satellite-Based Irradiance Estimates

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, Manajit [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gotseff, Peter [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2013-12-01

    This report describes an intercomparison of three popular broadband clear sky solar irradiance model results with measured data, as well as satellite-based model clear sky results compared to measured clear sky data. The authors conclude that one of the popular clear sky models (the Bird clear sky model developed by Richard Bird and Roland Hulstrom) could serve as a more accurate replacement for current satellite-model clear sky estimations. Additionally, the analysis of the model results with respect to model input parameters indicates that rather than climatological, annual, or monthly mean input data, higher-time-resolution input parameters improve the general clear sky model performance.

  3. Clear sky solar insolation data for Islamabad

    International Nuclear Information System (INIS)

    Akhter, P.; Baig, A.; Mufti, A.

    1990-09-01

    Monthly average values of both integrated and instantaneous clear sky solar radiation components for Islamabad territory have been presented and discussed. The components include total, direct normal, direct horizontal, global and diffuse radiations, sun hours, number of clear days and temperature for solar energy applications. Beam irradiance values are used to get clear sky (maximum) sun hours by ab-initio. The need for replacing the conventional sunshine recorder is discussed. (author). 8 refs, 1 fig, 2 tabs

  4. Clear-Sky Narrowband Albedo Datasets Derived from Modis Data

    Science.gov (United States)

    Chen, Y.; Minnis, P.; Sun-Mack, S.; Arduini, R. F.; Hong, G.

    2013-12-01

    Satellite remote sensing of clouds requires an accurate estimate of the clear-sky radiances for a given scene to detect clouds and aerosols and to retrieve their microphysical properties. Knowing the spatial and angular variability of clear-sky albedo is essential for predicting the clear-sky radiance at solar wavelengths. The Clouds and the Earth's Radiant Energy System (CERES) Project uses the near-infrared (NIR; 1.24, 1.6 or 2.13 μm) and visible (VIS; 0.63 μm) channels available on the Terra and Aqua Moderate Resolution Imaging Spectroradiometers (MODIS) to help identify clouds and retrieve their properties. Generally, clear-sky albedo for a given surface type is determined for conditions when the vegetation is either thriving or dormant and free of snow. The clear-sky albedos are derived using a radiative transfer parameterization of the impact of the atmosphere, including aerosols, on the observed reflectances. This paper presents the method of generating monthly clear-sky overhead albedo maps for both snow-free and snow-covered surfaces of these channels using one year of MODIS (Moderate Resolution Imaging Spectroradiometer) CERES products. Maps of 1.24 and 1.6 μm are being used as the background to help retrieve cloud properties (e.g., effective particle size, optical depth) in CERES cloud retrievals in both snow-free and snow-covered conditions.

  5. Uncertainties of parameterized surface downward clear-sky shortwave and all-sky longwave radiation.

    Science.gov (United States)

    Gubler, S.; Gruber, S.; Purves, R. S.

    2012-06-01

    As many environmental models rely on simulating the energy balance at the Earth's surface based on parameterized radiative fluxes, knowledge of the inherent model uncertainties is important. In this study we evaluate one parameterization of clear-sky direct, diffuse and global shortwave downward radiation (SDR) and diverse parameterizations of clear-sky and all-sky longwave downward radiation (LDR). In a first step, SDR is estimated based on measured input variables and estimated atmospheric parameters for hourly time steps during the years 1996 to 2008. Model behaviour is validated using the high quality measurements of six Alpine Surface Radiation Budget (ASRB) stations in Switzerland covering different elevations, and measurements of the Swiss Alpine Climate Radiation Monitoring network (SACRaM) in Payerne. In a next step, twelve clear-sky LDR parameterizations are calibrated using the ASRB measurements. One of the best performing parameterizations is elected to estimate all-sky LDR, where cloud transmissivity is estimated using measured and modeled global SDR during daytime. In a last step, the performance of several interpolation methods is evaluated to determine the cloud transmissivity in the night. We show that clear-sky direct, diffuse and global SDR is adequately represented by the model when using measurements of the atmospheric parameters precipitable water and aerosol content at Payerne. If the atmospheric parameters are estimated and used as a fix value, the relative mean bias deviance (MBD) and the relative root mean squared deviance (RMSD) of the clear-sky global SDR scatter between between -2 and 5%, and 7 and 13% within the six locations. The small errors in clear-sky global SDR can be attributed to compensating effects of modeled direct and diffuse SDR since an overestimation of aerosol content in the atmosphere results in underestimating the direct, but overestimating the diffuse SDR. Calibration of LDR parameterizations to local conditions

  6. Uncertainties of parameterized surface downward clear-sky shortwave and all-sky longwave radiation.

    Directory of Open Access Journals (Sweden)

    S. Gubler

    2012-06-01

    Full Text Available As many environmental models rely on simulating the energy balance at the Earth's surface based on parameterized radiative fluxes, knowledge of the inherent model uncertainties is important. In this study we evaluate one parameterization of clear-sky direct, diffuse and global shortwave downward radiation (SDR and diverse parameterizations of clear-sky and all-sky longwave downward radiation (LDR. In a first step, SDR is estimated based on measured input variables and estimated atmospheric parameters for hourly time steps during the years 1996 to 2008. Model behaviour is validated using the high quality measurements of six Alpine Surface Radiation Budget (ASRB stations in Switzerland covering different elevations, and measurements of the Swiss Alpine Climate Radiation Monitoring network (SACRaM in Payerne. In a next step, twelve clear-sky LDR parameterizations are calibrated using the ASRB measurements. One of the best performing parameterizations is elected to estimate all-sky LDR, where cloud transmissivity is estimated using measured and modeled global SDR during daytime. In a last step, the performance of several interpolation methods is evaluated to determine the cloud transmissivity in the night.

    We show that clear-sky direct, diffuse and global SDR is adequately represented by the model when using measurements of the atmospheric parameters precipitable water and aerosol content at Payerne. If the atmospheric parameters are estimated and used as a fix value, the relative mean bias deviance (MBD and the relative root mean squared deviance (RMSD of the clear-sky global SDR scatter between between −2 and 5%, and 7 and 13% within the six locations. The small errors in clear-sky global SDR can be attributed to compensating effects of modeled direct and diffuse SDR since an overestimation of aerosol content in the atmosphere results in underestimating the direct, but overestimating the diffuse SDR. Calibration of LDR parameterizations

  7. A simple formula for determining globally clear skies

    Energy Technology Data Exchange (ETDEWEB)

    Long, C.N.; George, A.T.; Mace, G.G. [Penn State Univ., University Park, PA (United States)] [and others

    1996-04-01

    Surface measurements to serve as {open_quotes}ground truth{close_quotes} are of primary importance in the development of retrieval algorithms using satellite measurements to predict surface irradiance. The most basic algorithms of this type deal with clear sky (i.e., cloudless) top-to-surface shortwave (SW) transfer, serving as a necessary prerequisite towards treating both clear and cloudy conditions. Recently, atmosphere SW cloud forcing to infer the possibility of excess atmospheric absorption (compared with model results) in cloudy atmospheres. The surface component of this ratio relies on inferring the expected clear sky SW irradiance to determine the effects of clouds on the SW energy budget. Solar renewable energy applications make use of clear and cloud fraction climatologies to assess solar radiation resources. All of the above depend to some extent on the identification of globally clear sky conditions and the attendant measurements of downwelling SW irradiance.

  8. Tropospheric haze and colors of the clear daytime sky.

    Science.gov (United States)

    Lee, Raymond L

    2015-02-01

    To casual observers, haze's visible effects on clear daytime skies may seem mundane: significant scattering by tropospheric aerosols visibly (1) reduces the luminance contrast of distant objects and (2) desaturates sky blueness. However, few published measurements of hazy-sky spectra and chromaticities exist to compare with these naked-eye observations. Hyperspectral imaging along sky meridians of clear and hazy skies at one inland and two coastal sites shows that they have characteristic colorimetric signatures of scattering and absorption by haze aerosols. In addition, a simple spectral transfer function and a second-order scattering model of skylight reveal the net spectral and colorimetric effects of haze.

  9. Development of software for estimating clear sky solar radiation in Indonesia

    Science.gov (United States)

    Ambarita, H.

    2017-01-01

    Research on solar energy applications in Indonesia has come under scrutiny in recent years. Solar radiation is harvested by solar collector or solar cell and convert the energy into useful energy such as heat and or electricity. In order to provide a better configuration of a solar collector or a solar cell, clear sky radiation should be estimated properly. In this study, an in-house software for estimating clear sky radiation is developed. The governing equations are solved simultaneously. The software is tested in Medan city by performing a solar radiation measurements. For clear sky radiation, the results of the software and measurements ones show a good agreement. However, for the cloudy sky condition it cannot predict the solar radiation. This software can be used to estimate the clear sky radiation in Indonesia.

  10. A new simple parameterization of daily clear-sky global solar radiation including horizon effects

    International Nuclear Information System (INIS)

    Lopez, Gabriel; Javier Batlles, F.; Tovar-Pescador, Joaquin

    2007-01-01

    Estimation of clear-sky global solar radiation is usually an important previous stage for calculating global solar radiation under all sky conditions. This is, for instance, a common procedure to derive incoming solar radiation from remote sensing or by using digital elevation models. In this work, we present a new model to calculate daily values of clear-sky global solar irradiation. The main goal is the simple parameterization in terms of atmospheric temperature and relative humidity, Angstroem's turbidity coefficient, ground albedo and site elevation, including a factor to take into account horizon obstructions. This allows us to obtain estimates even though a free horizon is not present as is the case of mountainous locations. Comparisons of calculated daily values with measured data show that this model is able to provide a good level of accurate estimates using either daily or mean monthly values of the input parameters. This new model has also been shown to improve daily estimates against those obtained using the clear-sky model from the European Solar Radiation Atlas and other accurate parameterized daily irradiation models. The introduction of Angstroem's turbidity coefficient and ground albedo should allow us to use the increasing worldwide aerosol information available and to consider those sites affected by snow covers in an easy and fast way. In addition, the proposed model is intended to be a useful tool to select clear-sky conditions

  11. Night sky luminance under clear sky conditions: Theory vs. experiment

    International Nuclear Information System (INIS)

    Kocifaj, Miroslav

    2014-01-01

    Sky glow is caused by both natural phenomena and factors of anthropogenic origin, and of the latter ground-based light sources are the most important contributors for they emit the spatially linked spectral radiant intensity distribution of artificial light sources, which are further modulated by local atmospheric optics and perceived as the diffuse light of a night sky. In other words, sky glow is closely related to a city's shape and pattern of luminaire distribution, in practical effect an almost arbitrary deployment of random orientation of heterogeneous electrical light sources. Thus the luminance gradation function measured in a suburban zone or near the edges of a city is linked to the City Pattern or vice versa. It is shown that clear sky luminance/radiance data recorded in an urban area can be used to retrieve the bulk luminous/radiant intensity distribution if some a-priori information on atmospheric aerosols is available. For instance, the single scattering albedo of aerosol particles is required under low turbidity conditions, as demonstrated on a targeted experiment in the city of Frýdek-Mistek. One of the main advantages of the retrieval method presented in this paper is that the single scattering approximation is satisfactorily accurate in characterizing the light field near the ground because the dominant contribution to the sky glow has originated from beams propagated along short optical paths. - Highlights: • Urban sky glow is interpreted in terms of city emission function. • Luminance function in a suburban zone is linked to the City Pattern. • Single scattering approximation is applicable in modeling urban sky glow. • Information on aerosols represents valuable inputs to the retrieval procedure. • Sky glow patterns vary with light source distribution and spectral emission

  12. Determination atmospheric conditions by evaluating clearness index, turbidity and brightness of the sky

    International Nuclear Information System (INIS)

    Kandilli, C.

    2005-01-01

    There are fifteen different sky types which range from totally overcast sky to low turbidity clear sky have been defined by CIE (International Commission on Illumination). For the applications of solar energy engineering and day lighting purposes, it has a great importance to determine the physical characteristics of atmosphere and the sky type. The most important parameters which define the sky type are clearness index, turbidity and brightness. In this study, the parameters of clearness index, turbidity and brightness of the sky belong to Izmir was calculated and their relations with solar radiation and its components were represented according to 10 years data (1994-2004) of meteorology station of Ege University Solar Energy Institute. In this study, clearness index, turbidity, sky clearness and brightness were evaluated to put forward the effects of the these parameters on the atmospheric condition for designing and engineering purposes

  13. NOAA AVHRR Clear-Sky Products over Oceans (ACSPO): Sea Surface Temperature, Clear Sky Radiances, and Aerosol Optical Depth for the Global Ocean, 2011 - present (NCEI Accession 0072979)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The AVHRR Clear-Sky Processor over Oceans, jointly developed between NESDIS STAR and OSDPD, produces AVHRR clear-sky products over oceans. ACSPO generates output...

  14. Predicting Clear-Sky Reflectance Over Snow/Ice in Polar Regions

    Science.gov (United States)

    Chen, Yan; Sun-Mack, Sunny; Arduini, Robert F.; Hong, Gang; Minnis, Patrick

    2015-01-01

    Satellite remote sensing of clouds requires an accurate estimate of the clear-sky radiances for a given scene to detect clouds and aerosols and to retrieve their microphysical properties. Knowing the spatial and angular variability of clear-sky albedo is essential for predicting clear-sky radiance at solar wavelengths. The Clouds and the Earth's Radiant Energy System (CERES) Project uses the nearinfrared (NIR; 1.24, 1.6 or 2.13 micrometers), visible (VIS; 0.63 micrometers) and vegetation (VEG; 0.86 micrometers) channels available on the Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) to help identify clouds and retrieve their properties in both snow-free and snow-covered conditions. Thus, it is critical to have reliable distributions of clear-sky albedo for all of these channels. In CERES Edition 4 (Ed4), the 1.24-micrometer channel is used to retrieve cloud optical depth over snow/ice-covered surfaces. Thus, it is especially critical to accurately predict the 1.24-micrometer clear-sky albedo alpha and reflectance rho for a given location and time. Snow albedo and reflectance patterns are very complex due to surface texture, particle shapes and sizes, melt water, and vegetation protrusions from the snow surface. To minimize those effects, this study focuses on the permanent snow cover of Antarctica where vegetation is absent and melt water is minimal. Clear-sky albedos are determined as a function of solar zenith angle (SZA) from observations over all scenes determined to be cloud-free to produce a normalized directional albedo model (DRM). The DRM is used to develop alpha(SZA=0 degrees) on 10 foot grid for each season. These values provide the basis for predicting r at any location and set of viewing & illumination conditions. This paper examines the accuracy of this approach for two theoretical snow surface reflectance models.

  15. Estimates of clear night sky emissivity in the Negev Highlands, Israel

    International Nuclear Information System (INIS)

    Tang Runsheng; Etzion, Y.; Meir, I.A.

    2004-01-01

    A simple method was introduced to estimate the atmospheric emissivity of clear night skies based on the water temperature variation inside an open shallow pond. The method used the pond as an absorber of atmospheric radiation by measuring the water evaporation rate from the pond to ambient air and then calculating the heat loss inside the pond due to the radiative heat exchange between the pond and sky dome. An empirical correlation for the calculations of clear night sky emissivity in the Negev Highlands, Israel, was found. It showed that the emissivity of clear night sky in the Negev Highlands is slightly lower than that expected by Berdahl et al. and Clark's correlations under the climatic conditions during the period of measurements

  16. Tropospheric haze and colors of the clear twilight sky.

    Science.gov (United States)

    Lee, Raymond L; Mollner, Duncan C

    2017-07-01

    At the earth's surface, clear-sky colors during civil twilights depend on the combined spectral effects of molecular scattering, extinction by tropospheric aerosols, and absorption by ozone. Molecular scattering alone cannot produce the most vivid twilight colors near the solar horizon, for which aerosol scattering and absorption are also required. However, less well known are haze aerosols' effects on twilight sky colors at larger scattering angles, including near the antisolar horizon. To analyze this range of colors, we compare 3D Monte Carlo simulations of skylight spectra with hyperspectral measurements of clear twilight skies over a wide range of aerosol optical depths. Our combined measurements and simulations indicate that (a) the purest antisolar twilight colors would occur in a purely molecular, multiple-scattering atmosphere, whereas (b) the most vivid solar-sky colors require at least some turbidity. Taken together, these results suggest that multiple scattering plays an important role in determining the redness of the antitwilight arch.

  17. MODIS Collection 6 Clear Sky Restoral (CSR): Filtering Cloud Mast 'Not Clear' Pixels

    Science.gov (United States)

    Meyer, Kerry G.; Platnick, Steven Edward; Wind, Galina; Riedi, Jerome

    2014-01-01

    Correctly identifying cloudy pixels appropriate for the MOD06 cloud optical and microphysical property retrievals is accomplished in large part using results from the MOD35 1km cloud mask tests (note there are also two 250m subpixel cloud mask tests that can convert the 1km cloudy designations to clear sky). However, because MOD35 is by design clear sky conservative (i.e., it identifies "not clear" pixels), certain situations exist in which pixels identified by MOD35 as "cloudy" are nevertheless likely to be poor retrieval candidates. For instance, near the edge of clouds or within broken cloud fields, a given 1km MODIS field of view (FOV) may in fact only be partially cloudy. This can be problematic for the MOD06 retrievals because in these cases the assumptions of a completely overcast homogenous cloudy FOV and 1-dimensional plane-parallel radiative transfer no longer hold, and subsequent retrievals will be of low confidence. Furthermore, some pixels may be identified by MOD35 as "cloudy" for reasons other than the presence of clouds, such as scenes with thick smoke or lofted dust, and should therefore not be retrieved as clouds. With such situations in mind, a Clear Sky Restoral (CSR) algorithm was introduced in C5 that attempts to identify pixels expected to be poor retrieval candidates. Table 1 provides SDS locations for CSR and partly cloudy (PCL) pixels.

  18. Quantifying the clear-sky bias of satellite-derived infrared LST

    Science.gov (United States)

    Ermida, S. L.; Trigo, I. F.; DaCamara, C.

    2017-12-01

    Land surface temperature (LST) is one of the most relevant parameters when addressing the physical processes that take place at the surface of the Earth. Satellite data are particularly appropriate for measuring LST over the globe with high temporal resolution. Remote-sensed LST estimation from space-borne sensors has been systematically performed over the Globe for nearly 3 decades and geostationary LST climate data records are now available. The retrieval of LST from satellite observations generally relies on measurements in the thermal infrared (IR) window. Although there is a large number of IR sensors on-board geostationary satellites and polar orbiters suitable for LST retrievals with different temporal and spatial resolutions, the use of IR observations limits LST estimates to clear sky conditions. As a consequence, climate studies based on IR LST are likely to be affected by the restriction of LST data to cloudless conditions. However, such "clear sky bias" has never been quantified and, therefore, the actual impact of relying only on clear sky data is still to be determined. On the other hand, an "all-weather" global LST database may be set up based on passive microwave (MW) measurements which are much less affected by clouds. An 8-year record of all-weather MW LST is here used to quantify the clear-sky bias of IR LST at global scale based on MW observations performed by the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) onboard NASA's Aqua satellite. Selection of clear-sky and cloudy pixels is based on information derived from measurements performed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the same satellite.

  19. Clear-sky narrowband albedos derived from VIRS and MODIS

    Science.gov (United States)

    Sun-Mack, Sunny; Minnis, Patrick; Chen, Yan; Arduini, Robert F.

    2004-02-01

    The Clouds and Earth"s Radiant Energy System (CERES) project is using multispectral imagers, the Visible Infrared Scanner (VIRS) on the tropical Rainfall Measuring Mission (TRMM) satellite and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra, operating since spring 2000, and Aqua, operating since summer 2002, to provide cloud and clear-sky properties at various wavelengths. This paper presents the preliminary results of an analysis of the CERES clear-sky reflectances to derive a set top-of-atmosphere clear sky albedo for 0.65, 0.86, 1.6, 2.13 μm, for all major surface types using the combined MODIS and VIRS datasets. The variability of snow albedo with surface type is examined using MODIS data. Snow albedo was found to depend on the vertical structure of the vegetation. At visible wavelengths, it is least for forested areas and greatest for smooth desert and tundra surfaces. At 1.6 and 2.1-μm, the snow albedos are relatively insensitive to the underlying surface because snow decreases the reflectance. Additional analyses using all of the MODIS results will provide albedo models that should be valuable for many remote sensing, simulation and radiation budget studies.

  20. Impacts of field of view configuration of Cross-track Infrared Sounder on clear-sky observations.

    Science.gov (United States)

    Wang, Likun; Chen, Yong; Han, Yong

    2016-09-01

    Hyperspectral infrared radiance measurements from satellite sensors contain valuable information on atmospheric temperature and humidity profiles and greenhouse gases, and therefore are directly assimilated into numerical weather prediction (NWP) models as inputs for weather forecasting. However, data assimilations in current operational NWP models still mainly rely on cloud-free observations due to the challenge of simulating cloud-contaminated radiances when using hyperspectral radiances. The limited spatial coverage of the 3×3 field of views (FOVs) in one field of regard (FOR) (i.e., spatial gap among FOVs) as well as relatively large footprint size (14 km) in current Cross-track Infrared Sounder (CrIS) instruments limits the amount of clear-sky observations. This study explores the potential impacts of future CrIS FOV configuration (including FOV size and spatial coverage) on the amount of clear-sky observations by simulation experiments. The radiance measurements and cloud mask products (VCM) from the Visible Infrared Imager Radiometer Suite (VIIRS) are used to simulate CrIS clear-sky observation under different FOV configurations. The results indicate that, given the same FOV coverage (e.g., 3×3), the percentage of clear-sky FOVs and the percentage of clear-sky FORs (that contain at least one clear-sky FOV) both increase as the FOV size decreases. In particular, if the CrIS FOV size were reduced from 14 km to 7 km, the percentage of clear-sky FOVs increases from 9.02% to 13.51% and the percentage of clear-sky FORs increases from 18.24% to 27.51%. Given the same FOV size but with increasing FOV coverage in each FOR, the clear-sky FOV observations increases proportionally with the increasing sampling FOVs. Both reducing FOV size and increasing FOV coverage can result in more clear-sky FORs, which benefit data utilization of NWP data assimilation.

  1. Comparison of the observed and calculated clear sky greenhouse effect - Implications for climate studies

    Science.gov (United States)

    Kiehl, J. T.; Briegleb, B. P.

    1992-01-01

    The clear sky greenhouse effect is defined in terms of the outgoing longwave clear sky flux at the top of the atmosphere. Recently, interest in the magnitude of the clear sky greenhouse effect has increased due to the archiving of the clear sky flux quantity through the Earth Radiation Budget Experiment (ERBE). The present study investigates to what degree of accuracy this flux can be analyzed by using independent atmospheric and surface data in conjunction with a detailed longwave radiation model. The conclusion from this comparison is that for most regions over oceans the analyzed fluxes agree to within the accuracy of the ERBE-retrieved fluxes (+/- 5 W/sq m). However, in regions where deep convective activity occurs, the ERBE fluxes are significantly higher (10-15 W/sq m) than the calculated fluxes. This bias can arise from either cloud contamination problems or variability in water vapor amount. It is argued that the use of analyzed fluxes may provide a more consistent clear sky flux data set for general circulation modeling validation. Climate implications from the analyzed fluxes are explored. Finally, results for obtaining longwave surface fluxes over the oceans are presented.

  2. New gridded database of clear-sky solar radiation derived from ground-based observations over Europe

    Science.gov (United States)

    Bartok, Blanka; Wild, Martin; Sanchez-Lorenzo, Arturo; Hakuba, Maria Z.

    2017-04-01

    Since aerosols modify the entire energy balance of the climate system through different processes, assessments regarding aerosol multiannual variability are highly required by the climate modelling community. Because of the scarcity of long-term direct aerosol measurements, the retrieval of aerosol data/information from other type of observations or satellite measurements are very relevant. One approach frequently used in the literature is analyze of the clear-sky solar radiation which offer a better overview of changes in aerosol content. In the study first two empirical methods are elaborated in order to separate clear-sky situations from observed values of surface solar radiation available at the World Radiation Data Center (WRDC), St. Petersburg. The daily data has been checked for temporal homogeneity by applying the MASH method (Szentimrey, 2003). In the first approach, clear sky situations are detected based on clearness index, namely the ratio of the surface solar radiation to the extraterrestrial solar irradiation. In the second approach the observed values of surface solar radiation are compared to the climatology of clear-sky surface solar radiation calculated by the MAGIC radiation code (Muller et al. 2009). In both approaches the clear-sky radiation values highly depend on the applied thresholds. In order to eliminate this methodological error a verification of clear-sky detection is envisaged through a comparison with the values obtained by a high time resolution clear-sky detection and interpolation algorithm (Long and Ackermann, 2000) making use of the high quality data from the Baseline Surface Radiation Network (BSRN). As the consequences clear-sky data series are obtained for 118 European meteorological stations. Next a first attempt has been done in order to interpolate the point-wise clear-sky radiation data by applying the MISH (Meteorological Interpolation based on Surface Homogenized Data Basis) method for the spatial interpolation of

  3. Impact of atmospheric components on solar clear-sky models at different elevation: Case study Canary Islands

    International Nuclear Information System (INIS)

    Antonanzas-Torres, F.; Antonanzas, J.; Urraca, R.; Alia-Martinez, M.; Martinez-de-Pison, F.J.

    2016-01-01

    Highlights: • Assessment on the performance of solar clear-sky models at different altitude. • SOLIS and REST2 clear-sky models were superior with fine atmospheric inputs. • ESRA proved more robust with low spatial resolution atmospheric inputs. • Over-estimation occurred at the lower site when using inputs from the upper site. - Abstract: The estimation of clear-sky solar irradiance via clear-sky models depends on reliable values of aerosol optical depth, water vapor and ozone content. These atmospheric variables are rarely on-site measured and are generally provided as gridded estimates in very low spatial resolution (1°). The high spatial variability of atmospheric variables within the grid resolution (pixel) leads to important errors in those areas with great atmospheric variability, such as in mountainous regions. In this paper, the performance of three clear-sky solar irradiance models was evaluated in a site with especially great elevation range, the Izana station from the Baseline Surface Radiation Network (Tenerife, Canary Islands) located at a high elevation (2373 m) and just 14 km from the ocean. Aerosols data were obtained from measurements from the Aerosol Robotic Network (AERONET) at the same site. The evaluation was also compared with global horizontal irradiance estimations with clear-sky models in the Guimar station, located at a lower elevation (156 m) and only 11.5 km away from Izana. Results showed a strong influence of elevation on solar radiation estimation under clear-sky conditions.

  4. Spectral and diurnal variations in clear sky planetary albedo

    Science.gov (United States)

    Briegleb, B.; Ramanathan, V.

    1982-01-01

    Spectral and diurnal variations in the clear sky planetary albedo of the earth are calculated using a radiative transfer model to obtain January and July values for a 5 deg x 5 deg global grid. The model employs observed climatological values of temperatures, humidities, snow and sea-ice cover. The diurnal cycle of clear sky albedo is calculated in the following intervals: 0.2-0.5, 0.5-0.7, and 0.7-4 microns. Observed ozone distribution is specified as a function of latitude and season. The 0.2-0.5 micron spectral albedo is 10-20% higher than the total albedo for all latitudes because of Rayleigh scattering; the 0.5-0.7 micron albedo differs from the total albedo by 1-2% for most latitudes, while the 0.7-4 micron albedo is 5-10% lower than the total because of strong atmospheric absorption. Planetary albedo decreases from morning to local noon, with diurnal variations being particularly strong over water.

  5. Clear-Sky Narrowband Albedo Variations Derived from VIRS and MODIS Data

    Science.gov (United States)

    Sun-Mack, Sunny; Chen, Yan; Arduini, Robert F.; Minnis, Patrick

    2004-01-01

    A critical parameter for detecting clouds and aerosols and for retrieving their microphysical properties is the clear-sky radiance. The Clouds and the Earth's Radiant Energy System (CERES) Project uses the visible (VIS; 0.63 m) and near-infrared (NIR; 1.6 or 2.13 m) channels available on same satellites as the CERES scanners. Another channel often used for cloud and aerosol, and vegetation cover retrievals is the vegetation (VEG; 0.86- m) channel that has been available on the Advanced Very High Resolution Radiometer (AVHRR) for many years. Generally, clear-sky albedo for a given surface type is determined for conditions when the vegetation is either thriving or dormant and free of snow. Snow albedo is typically estimated without considering the underlying surface type. The albedo for a surface blanketed by snow, however, should vary with surface type because the vegetation often emerges from the snow to varying degrees depending on the vertical dimensions of the vegetation. For example, a snowcovered prairie will probably be brighter than a snowcovered forest because the snow typically falls off the trees exposing the darker surfaces while the snow on a grassland at the same temperatures will likely be continuous and, therefore, more reflective. Accounting for the vegetation-induced differences should improve the capabilities for distinguishing snow and clouds over different surface types and facilitate improvements in the accuracy of radiative transfer calculations between the snow-covered surface and the atmosphere, eventually leading to improvements in models of the energy budgets over land. This paper presents a more complete analysis of the CERES spectral clear-sky reflectances to determine the variations in clear-sky top-of-atmosphere (TOA) albedos for both snow-free and snow-covered surfaces for four spectral channels using data from Terra and Aqua.. The results should be valuable for improved cloud retrievals and for modeling radiation fields.

  6. Photosynthetically-active radiation: sky radiance distributions under clear and overcast conditions

    International Nuclear Information System (INIS)

    Grant, R.H.; Heisler, G.M.; Gao, W.

    1996-01-01

    The photosynthetically active radiation (PAR), defined as the wavelength band of 0.400 μm to 0.700 μm, represents most of the visible solar radiation. Although the proportion of global irradiance that originates from diffuse sky radiation is higher for PAR than for all solar shortwave radiation, it is often assumed that the PAR diffuse sky radiation is distributed identically to that of all shortwave solar radiation. This assumption has not been tested. PAR sky radiance measurements were made in a rural area over a wide range of solar zenith angles. The distribution of PAR sky radiance was modeled using physically-based, non-linear equations.For clear skies, the normalized sky radiance distribution (N) was best modeled using the scattering angle (ψ) and the zenith position in the sky (Θ) as N (Θ, ψ) = 0.0361 [6.3 + (1 + cos 2 Θ / (1 - cos ψ)] [1-e -0.31 sec ( Θ]. The angle Ψ is defined by cos ψ = cos Θ cos Θ * + sin Θ sin Θ * cos Φ, where solar zenith angle is Θ* and the difference in azimuth between the sun and the position in the sky is Φ. Modeling of the overcast sky depended on the visibility of the solar disk. The translucent middle/high cloud overcast conditions (cloud base greater than 300 m above ground level) were best modeled as: N(Θ∗, ψ) = 0.149 + 0.084Θ∗ + 1.305e −2.5ψ while the translucent low cloud overcast conditions (cloud base less than 300 m above ground level) were best modeled as: N(Θ∗, ψ) = 0.080 + 0.058Θ∗ + 0.652e −2.1ψ . The obscured overcast sky condition (solar disk obscured) was best modeled as: N(Θ) = 0.441 [1 + 4.6cos Θ] /[1 + 4.6]. The unit of N for all equations is π Sr −1 , so that integration of each function over the sky hemisphere yields 1.0.These equations can be applied directly to the sky diffuse irradiance on the horizontal, I diff , to provide radiance distributions for the sky. Estimates of actual sky radiance distribution can be estimated from N a (Θ, ψ) = I diff N(Θ,

  7. A Supplementary Clear-Sky Snow and Ice Recognition Technique for CERES Level 2 Products

    Science.gov (United States)

    Radkevich, Alexander; Khlopenkov, Konstantin; Rutan, David; Kato, Seiji

    2013-01-01

    Identification of clear-sky snow and ice is an important step in the production of cryosphere radiation budget products, which are used in the derivation of long-term data series for climate research. In this paper, a new method of clear-sky snow/ice identification for Moderate Resolution Imaging Spectroradiometer (MODIS) is presented. The algorithm's goal is to enhance the identification of snow and ice within the Clouds and the Earth's Radiant Energy System (CERES) data after application of the standard CERES scene identification scheme. The input of the algorithm uses spectral radiances from five MODIS bands and surface skin temperature available in the CERES Single Scanner Footprint (SSF) product. The algorithm produces a cryosphere rating from an aggregated test: a higher rating corresponds to a more certain identification of the clear-sky snow/ice-covered scene. Empirical analysis of regions of interest representing distinctive targets such as snow, ice, ice and water clouds, open waters, and snow-free land selected from a number of MODIS images shows that the cryosphere rating of snow/ice targets falls into 95% confidence intervals lying above the same confidence intervals of all other targets. This enables recognition of clear-sky cryosphere by using a single threshold applied to the rating, which makes this technique different from traditional branching techniques based on multiple thresholds. Limited tests show that the established threshold clearly separates the cryosphere rating values computed for the cryosphere from those computed for noncryosphere scenes, whereas individual tests applied consequently cannot reliably identify the cryosphere for complex scenes.

  8. The earth's radiation budget and its relation to atmospheric hydrology. I - Observations of the clear sky greenhouse effect. II - Observations of cloud effects

    Science.gov (United States)

    Stephens, Graeme L.; Greenwald, Thomas J.

    1991-01-01

    The clear-sky components of the earth's radiation budget (ERB), the relationship of these components to the sea surface temperature (SST), and microwave-derived water-vapor amount are analyzed in an observational study along with the relationship between the cloudy-sky components of ERB and space/time coincident observations of SST, microwave-derived cloud liquid water, and cloud cover. The purpose of the study is to use these observations for establishing an understanding of the couplings between radiation and the atmosphere that are important to understanding climate feedback. A strategy for studying the greenhouse effect of earth by analyzing the emitted clear-sky longwave flux over the ocean is proposed. It is concluded that the largest observed influence of clouds on ERB is more consistent with macrophysical properties of clouds as opposed to microphysical properties. The analysis for clouds and the greenhouse effect of clouds is compared quantitatively with the clear sky results. Land-ocean differences and tropical-midlatitude differences are shown and explained in terms of the cloud macrostructure.

  9. Spectral and Spatial UV Sky Radiance Measurements at a Seaside Resort Under Clear Sky and Slightly Overcast Conditions.

    Science.gov (United States)

    Sandmann, Henner; Stick, Carsten

    2014-01-01

    Spatial measurements of the diffusely scattered sky radiance at a seaside resort under clear sky and slightly overcast conditions have been used to calculate the sky radiance distribution across the upper hemisphere. The measurements were done in the summer season when solar UV radiation is highest. The selected wavelengths were 307, 350 and 550 nm representing the UVB, UVA and VIS band. Absolute values of radiance differ considerably between the wavelengths. Normalizing the measured values by use of direct solar radiance made the spatial distributions of unequal sky radiance comparable. The results convey a spatial impression of the different distributions of the radiance at the three wavelengths. Relative scattered radiance intensity is one order of magnitude greater in UVB than in VIS, whereas in UVA lies roughly in between. Under slightly overcast conditions scattered radiance is increased at all three wavelengths by about one order of magnitude. These measurements taken at the seaside underline the importance of diffuse scattered radiance. The effect of shading parts of the sky can be estimated from the distribution of sky radiance. This knowledge might be useful for sun seekers and in the treatment of people staying at the seaside for therapeutic purposes. © 2013 The American Society of Photobiology.

  10. Semi-empirical models for the estimation of clear sky solar global and direct normal irradiances in the tropics

    International Nuclear Information System (INIS)

    Janjai, S.; Sricharoen, K.; Pattarapanitchai, S.

    2011-01-01

    Highlights: → New semi-empirical models for predicting clear sky irradiance were developed. → The proposed models compare favorably with other empirical models. → Performance of proposed models is comparable with that of widely used physical models. → The proposed models have advantage over the physical models in terms of simplicity. -- Abstract: This paper presents semi-empirical models for estimating global and direct normal solar irradiances under clear sky conditions in the tropics. The models are based on a one-year period of clear sky global and direct normal irradiances data collected at three solar radiation monitoring stations in Thailand: Chiang Mai (18.78 o N, 98.98 o E) located in the North of the country, Nakhon Pathom (13.82 o N, 100.04 o E) in the Centre and Songkhla (7.20 o N, 100.60 o E) in the South. The models describe global and direct normal irradiances as functions of the Angstrom turbidity coefficient, the Angstrom wavelength exponent, precipitable water and total column ozone. The data of Angstrom turbidity coefficient, wavelength exponent and precipitable water were obtained from AERONET sunphotometers, and column ozone was retrieved from the OMI/AURA satellite. Model validation was accomplished using data from these three stations for the data periods which were not included in the model formulation. The models were also validated against an independent data set collected at Ubon Ratchathani (15.25 o N, 104.87 o E) in the Northeast. The global and direct normal irradiances calculated from the models and those obtained from measurements are in good agreement, with the root mean square difference (RMSD) of 7.5% for both global and direct normal irradiances. The performance of the models was also compared with that of other models. The performance of the models compared favorably with that of empirical models. Additionally, the accuracy of irradiances predicted from the proposed model are comparable with that obtained from some

  11. Daylighting on the working plane in oriented attic rooms under overcast and clear sky

    Directory of Open Access Journals (Sweden)

    Kondáš Kristián

    2014-06-01

    Full Text Available The evaluation of daylight conditions in building interiors is based on the Daylight Factor concept after current Slovak standards. Criteria and requirements determined in these standards consider the worst daylight exterior conditions which are described by CIE overcast sky model. The sky luminance distribution of overcast sky is centrical to the zenith, so independence of window orientation to cardinal points is characteristic in daylighting calculations. The sky luminance distribution modelling is one of the main task of the daylight source research more than 50 years. It is evident that also other types of sky conditions exist in nature. An introduction of a new criterion based on photometric variables, which also consider sunlight influence, is expected. This article represents a study of the influence of the interior orientation on distribution of daylighting in attic spaces under an overcast and clear sky

  12. Improving HelioClim-3 estimates of surface solar irradiance using the McClear clear-sky model and recent advances in atmosphere composition

    Directory of Open Access Journals (Sweden)

    Z. Qu

    2014-11-01

    Full Text Available The HelioClim-3 database (HC3v3 provides records of surface solar irradiation every 15 min, estimated by processing images from the geostationary meteorological Meteosat satellites using climatological data sets of the atmospheric Linke turbidity factor. This technical note proposes a method to improve a posteriori HC3v3 by combining it with data records of the irradiation under clear skies from the new McClear clear-sky model, whose inputs are the advanced global aerosol property forecasts and physically consistent total column content in water vapour and ozone produced by the MACC (Monitoring Atmosphere Composition and Climate projects. The method is validated by comparison with a series of ground measurements for 15 min and 1 h for 6 stations and for daily irradiation for 23 stations. The correlation coefficient is large, greater than respectively 0.92, 0.94, and 0.97, for 15 min, 1 h and daily irradiation. The bias ranges from −4 to 4% of the mean observed irradiation for most sites. The relative root mean square difference (RMSD varies between 14 and 38% for 15 min, 12 and 33% for 1 h irradiation, and 6 and 20% for daily irradiation. As a rule of thumb, the farther from the nadir of the Meteosat satellite located at latitude 0° and longitude 0°, and the greater the occurrence of fragmented cloud cover, the greater the relative RMSD. The method improves HC3v3 in most cases, and with no degradation in the others. A systematic correction of HC3v3 with McClear is recommended.

  13. First comparison of formaldehyde integral contents in ABL retrieved during clear-sky and overcast conditions by ZDOAS technique

    Science.gov (United States)

    Ivanov, Victor; Borovski, Alexander; Postylyakov, Oleg

    2017-10-01

    Formaldehyde (HCHO) is involved in a lot of chemical reactions in the atmosphere. Taking into account that HCHO basically undergo by photolysis and reaction with hydroxyl radical within a few hours, short-lived VOCs and direct HCHO emissions can cause local HCHO enhancement over certain areas, and, hence, exceeding background level of HCHO can be examined as a local pollution of the atmosphere by VOCs or existence of a local HCHO source. Several retrieval algorithms applicable for DOAS measurements in cloudless were previously developed. In previous works we proposed a new algorithm applicable for the overcast conditions. The algorithm has the typical F-coefficient error of about 10% for winter season, about 5% for summer season, and varying from 15 to 45% for transition season if the atmospheric boundary layer is below the cloud base. In this paper we briefly present our results of the HCHO vertical column retrieval measured at Zvenigorod Scientific Station (ZSS) for overcast. ZSS (55°41'49''N, 36°46'29''E) is located in Moscow region in 38 km west from Moscow. Because Western winds prevail in this region, ZSS is a background station the most part of time. But in cases of Eastern wind, the air quality at ZSS is affected by Moscow megapolis, and polluted air masses formed above Moscow can reach station in a few hours. Due to the absence of alternative overcast data of HCHO, we compare our overcast data with the HCHO vertical content, which we obtained for clear sky. We investigate similarities and differences in their statistical behavior in different air mass. The average overcast HCHO data have similar to clear-sky HCHO positive temperature trends for all wind direction. We found that the average retrieved overcast HCHO contents are systematically greater than the clear-sky retrieval data. But the difference between data retrieved for the overcast and clear-sky conditions are different for Eastern and Western winds. This difference is about 0.5×1016 mol cm-2

  14. The effect of clear sky radiation on crop surface temperature determined by thermal thermometry

    International Nuclear Information System (INIS)

    Svendsen, H.; Jensen, H.E.; Jensen, S.E.; Mogensen, V.O.

    1990-01-01

    By numerical integration of Planck's radiation function, a relationship between emitted radiation from a black body in the wavelength band 8–14 μm and the corresponding surface temperature was obtained. Using this relationship, an equation was developed relating the temperature error at different temperatures to the crop surface emissivity and clear sky radiation. It is concluded that the temperature error to be expected from neglect of clear sky radiation in the wavelength band 8–14μm in radiometric crop surface temperature determination is < 0.2 and 0.1 °C for crops with an emissivity > 0.96 and 0.98, respectively, for a leaf temperature range from 0 to 30°C

  15. High Turbidity Solis Clear Sky Model: Development and Validation

    Directory of Open Access Journals (Sweden)

    Pierre Ineichen

    2018-03-01

    Full Text Available The Solis clear sky model is a spectral scheme based on radiative transfer calculations and the Lambert–Beer relation. Its broadband version is a simplified fast analytical version; it is limited to broadband aerosol optical depths lower than 0.45, which is a weakness when applied in countries with very high turbidity such as China or India. In order to extend the use of the original simplified version of the model for high turbidity values, we developed a new version of the broadband Solis model based on radiative transfer calculations, valid for turbidity values up to 7, for the three components, global, beam, and diffuse, and for the four aerosol types defined by Shettle and Fenn. A validation of low turbidity data acquired in Geneva shows slightly better results than the previous version. On data acquired at sites presenting higher turbidity data, the bias stays within ±4% for the beam and the global irradiances, and the standard deviation around 5% for clean and stable condition data and around 12% for questionable data and variable sky conditions.

  16. The clear-sky greenhouse effect sensitivity to a sea surface temperature change

    Science.gov (United States)

    Duvel, J. PH.; Breon, F. M.

    1991-01-01

    The clear-sky greenhouse effect response to a sea surface temperature (SST or Ts) change is studied using outgoing clear-sky longwave radiation measurements from the Earth Radiation Budget Experiment. Considering geographical distributions for July 1987, the relation between the SST, the greenhouse effect (defined as the outgoing infrared flux trapped by atmospheric gases), and the precipitable water vapor content (W), estimated by the Special Sensor Microwave Imager, is analyzed first. A fairly linear relation between W and the normalized greenhouse effect g, is found. On the contrary, the SST dependence of both W and g exhibits nonlinearities with, especially, a large increase for SST above 25 C. This enhanced sensitivity of g and W can be interpreted in part by a corresponding large increase of atmospheric water vapor content related to the transition from subtropical dry regions to equatorial moist regions. Using two years of data (1985 and 1986), the normalized greenhouse effect sensitivity to the sea surface temperature is computed from the interannual variation of monthly mean values.

  17. Tropical High Cloud Fraction Controlled by Cloud Lifetime Rather Than Clear-sky Convergence

    Science.gov (United States)

    Seeley, J.; Jeevanjee, N.; Romps, D. M.

    2016-12-01

    Observations and simulations show a peak in cloud fraction below the tropopause. This peak is usually attributed to a roughly co-located peak in radiatively-driven clear-sky convergence, which is presumed to force convective detrainment and thus promote large cloud fraction. Using simulations of radiative-convective equilibrium forced by various radiative cooling profiles, we refute this mechanism by showing that an upper-tropospheric peak in cloud fraction persists even in simulations with no peak in clear-sky convergence. Instead, cloud fraction profiles seem to be controlled by cloud lifetimes — i.e., how long it takes for clouds to dissipate after they have detrained. A simple model of cloud evaporation shows that the small saturation deficit in the upper troposphere greatly extends cloud lifetimes there, while the large saturation deficit in the lower troposphere causes condensate to evaporate quickly. Since cloud mass flux must go to zero at the tropopause, a peak in cloud fraction emerges at a "sweet spot" below the tropopause where cloud lifetimes are long and there is still sufficient mass flux to be detrained.

  18. NOAA Climate Data Record (CDR) of Cloud and Clear-Sky Radiation Properties, Version 1.0

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NASA LaRC cloud and clear sky radiation properties dataset is generated using algorithms initially developed for application to TRMM and MODIS imagery within the...

  19. Inter-comparison of different models for estimating clear sky solar global radiation for the Negev region of Israel

    International Nuclear Information System (INIS)

    Ianetz, Amiran; Lyubansky, Vera; Setter, Ilan; Kriheli, Boris; Evseev, Efim G.; Kudish, Avraham I.

    2007-01-01

    Solar global radiation is a function of solar altitude, site altitude, albedo, atmospheric transparency and cloudiness, whereas solar global radiation on a clear day is defined such that it is a function of all the abovementioned parameters except cloudiness. Consequently, analysis of the relative magnitudes of solar global radiation and solar global radiation on a clear day provides a platform for studying the influence of cloudiness on solar global radiation. The Iqbal filter for determining the day type has been utilized to calculate the monthly average clear day solar global radiation at three sites in the Negev region of Israel. An inter-comparison between four models for estimating clear sky solar global radiation at the three sites was made. The relative accuracy of the four models was determined by comparing the monthly average daily clear sky solar global radiation to that determined using the Iqbal filter. The analysis was performed on databases consisting of measurements made during the time interval of January 1991 to December 2004. The monthly average daily clear sky solar global radiation determined by the Berlynd model was found to give the best agreement with that determined using the Iqbal filter. The Berlynd model was then utilized to calculate a daily clear day index, K c , which is defined as the ratio of the daily solar global radiation to the daily clear day solar global radiation. It is suggested that this index be used as an indication of the degree of cloudiness. Linear regression analysis was performed on the individual monthly databases for each site to determine the correlation between the daily clear day index and the daily clearness index, K T

  20. Practical models to estimate horizontal irradiance in clear sky conditions: Preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Salazar, German A.; Hernandez, Alejandro L.; Saravia, Luis R. [Department of Physics, School of Exact Sciences, National University of Salta, Bolivia Avenue 5150, 4400 Salta Capital (Argentina); INENCO (Institute of Non Conventional Energy Research), Bolivia Avenue 5150, 4400 Salta Capital (Argentina)

    2010-11-15

    The Argentinean Northwest (ANW) is a high altitude region located alongside Los Andes Mountains. The ANW is also one of the most insolated regions in the world due to its altitude and particular climate. However, the characterization of the solar resource in the region is incomplete as there are no stations to measure solar radiation continuously and methodically. With irradiance data recently having been measured at three sites in the Salta Province, a study was carried out that resulted in a practical model to quickly and efficiently estimate the horizontal irradiance in high altitude sites in clear sky conditions. This model uses the altitude above sea level (A) as a variable and generates a representative clearness index as a result (k{sub t-R}) that is calculated for each site studied. This index k{sub t-R} is then used with the relative optical air mass and the extraterrestrial irradiance to estimate the instantaneous clearness index (k{sub t}). Subsequently, the index k{sub t-R} is corrected by introducing the atmospheric pressure in the definition of relative optical air mass proposed by Kasten. The results are satisfactory as errors in the irradiance estimations with respect to measured values do not exceed 5% for pressure corrected air masses AM{sub c} < 2. This model will be used in a feasibility study to locate sites for the installation of solar thermal power plants in the ANW. A prototype of a CLFR solar power plant is being built in the INENCO Campus, at the National University of Salta. (author)

  1. DISCRIMINATING BETWEEN CLOUDY, HAZY, AND CLEAR SKY EXOPLANETS USING REFRACTION

    Energy Technology Data Exchange (ETDEWEB)

    Misra, Amit K.; Meadows, Victoria S. [Astronomy Department, University of Washington, Seattle, WA 98195 (United States)

    2014-11-01

    We propose a method to distinguish between cloudy, hazy, and clear sky (free of clouds and hazes) exoplanet atmospheres that could be applicable to upcoming large aperture space- and ground-based telescopes such as the James Webb Space Telescope (JWST) and the European Extremely Large Telescope (E-ELT). These facilities will be powerful tools for characterizing transiting exoplanets, but only after a considerable amount of telescope time is devoted to a single planet. A technique that could provide a relatively rapid means of identifying haze-free targets (which may be more valuable targets for characterization) could potentially increase the science return for these telescopes. Our proposed method utilizes broadband observations of refracted light in the out-of-transit spectrum. Light refracted through an exoplanet atmosphere can lead to an increase of flux prior to ingress and subsequent to egress. Because this light is transmitted at pressures greater than those for typical cloud and haze layers, the detection of refracted light could indicate a cloud- or haze-free atmosphere. A detection of refracted light could be accomplished in <10 hr for Jovian exoplanets with JWST and <5 hr for super-Earths/mini-Neptunes with E-ELT. We find that this technique is most effective for planets with equilibrium temperatures between 200 and 500 K, which may include potentially habitable planets. A detection of refracted light for a potentially habitable planet would strongly suggest the planet was free of a global cloud or haze layer, and therefore a promising candidate for follow-up observations.

  2. DISCRIMINATING BETWEEN CLOUDY, HAZY, AND CLEAR SKY EXOPLANETS USING REFRACTION

    International Nuclear Information System (INIS)

    Misra, Amit K.; Meadows, Victoria S.

    2014-01-01

    We propose a method to distinguish between cloudy, hazy, and clear sky (free of clouds and hazes) exoplanet atmospheres that could be applicable to upcoming large aperture space- and ground-based telescopes such as the James Webb Space Telescope (JWST) and the European Extremely Large Telescope (E-ELT). These facilities will be powerful tools for characterizing transiting exoplanets, but only after a considerable amount of telescope time is devoted to a single planet. A technique that could provide a relatively rapid means of identifying haze-free targets (which may be more valuable targets for characterization) could potentially increase the science return for these telescopes. Our proposed method utilizes broadband observations of refracted light in the out-of-transit spectrum. Light refracted through an exoplanet atmosphere can lead to an increase of flux prior to ingress and subsequent to egress. Because this light is transmitted at pressures greater than those for typical cloud and haze layers, the detection of refracted light could indicate a cloud- or haze-free atmosphere. A detection of refracted light could be accomplished in <10 hr for Jovian exoplanets with JWST and <5 hr for super-Earths/mini-Neptunes with E-ELT. We find that this technique is most effective for planets with equilibrium temperatures between 200 and 500 K, which may include potentially habitable planets. A detection of refracted light for a potentially habitable planet would strongly suggest the planet was free of a global cloud or haze layer, and therefore a promising candidate for follow-up observations

  3. Development of the ClearSky smoke dispersion forecast system for agricultural field burning in the Pacific Northwest

    Science.gov (United States)

    Jain, Rahul; Vaughan, Joseph; Heitkamp, Kyle; Ramos, Charleston; Claiborn, Candis; Schreuder, Maarten; Schaaf, Mark; Lamb, Brian

    The post-harvest burning of agricultural fields is commonly used to dispose of crop residue and provide other desired services such as pest control. Despite careful regulation of burning, smoke plumes from field burning in the Pacific Northwest commonly degrade air quality, particularly for rural populations. In this paper, ClearSky, a numerical smoke dispersion forecast system for agricultural field burning that was developed to support smoke management in the Inland Pacific Northwest, is described. ClearSky began operation during the summer through fall burn season of 2002 and continues to the present. ClearSky utilizes Mesoscale Meteorological Model version 5 (MM5v3) forecasts from the University of Washington, data on agricultural fields, a web-based user interface for defining burn scenarios, the Lagrangian CALPUFF dispersion model and web-served animations of plume forecasts. The ClearSky system employs a unique hybrid source configuration, which treats the flaming portion of a field as a buoyant line source and the smoldering portion of the field as a buoyant area source. Limited field observations show that this hybrid approach yields reasonable plume rise estimates using source parameters derived from recent field burning emission field studies. The performance of this modeling system was evaluated for 2003 by comparing forecast meteorology against meteorological observations, and comparing model-predicted hourly averaged PM 2.5 concentrations against observations. Examples from this evaluation illustrate that while the ClearSky system can accurately predict PM 2.5 surface concentrations due to field burning, the overall model performance depends strongly on meteorological forecast error. Statistical evaluation of the meteorological forecast at seven surface stations indicates a strong relationship between topographical complexity near the station and absolute wind direction error with wind direction errors increasing from approximately 20° for sites in

  4. Improved Estimates of Clear Sky Longwave Flux and Application to the Tropical Greenhouse Effect

    Science.gov (United States)

    Collins, W. D.

    1997-01-01

    The first objective of this investigation is to eliminate the clear-sky offset introduced by the scene-identification procedures developed for the Earth Radiation Budget Experiment (ERBE). Estimates of this systematic bias range from 10 to as high as 30 W/sq m. The initial version of the ScaRaB data is being processed with the original ERBE algorithm. Since the ERBE procedure for scene identification is based upon zonal flux averages, clear scenes with longwave emission well below the zonal mean value are mistakenly classified as cloudy. The erroneous classification is more frequent in regions with deep convection and enhanced mid- and upper-tropospheric humidity. We will develop scene identification parameters with zonal and/or time dependence to reduce or eliminate the bias in the clear- sky data. The modified scene identification procedure could be used for the ScaRaB-specific version of the Earth-radiation products. The second objective is to investigate changes in the clear-sky Outgoing Longwave Radiation (OLR) associated with decadal variations in the tropical and subtropical climate. There is considerable evidence for a shift in the climate state starting in approximately 1977. The shift is accompanied by higher SSTs in the equatorial Pacific, increased tropical convection, and higher values of atmospheric humidity. Other evidence indicates that the humidity in the tropical troposphere has been steadily increasing over the last 30 years. It is not known whether the atmospheric greenhouse effect has increased during this period in response to these changes in SST and precipitable water. We will investigate the decadal-scale fluctuations in the greenhouse effect using Nimbus-7, ERBE, and ScaRaB measurements spaning 1979 to the present. The data from the different satellites will be intercalibrated by comparison with model calculations based upon ship radiosonde observations. The fluxes calculated from the radiation model will also be used for validation of the

  5. A Climate-Data Record (CDR) of the "Clear-Sky" Surface Temperature of the Greenland Ice Sheet

    Science.gov (United States)

    Hall, Dorothy K.; Comiso, Josefino C.; DiGirolamo, Nocolo E.; Shuman, Christopher A.

    2011-01-01

    We have developed a climate-data record (CDR) of "clear-sky" ice-surface temperature (IST) of the Greenland Ice Sheet using Moderate-Resolution Imaging Spectroradiometer (MODIS) data. The CDR provides daily and monthly-mean IST from March 2000 through December 2010 on a polar stereographic projection at a resolution of 6.25 km. The CDR is amenable to extension into the future using Visible/Infrared Imager Radiometer Suite (VIIRS) data. Regional "clear-sky" surface temperature increases since the early 1980s in the Arctic, measured using Advanced Very High Resolution Radiometer (AVHRR) infrared data, range from 0.57 +/- 0.02 to 0.72 +/- 0.1 c per decade. Arctic warming has important implications for ice-sheet mass balance because much of the periphery of the Greenland Ice Sheet is already near O C during the melt season, and is thus vulnerable to rapid melting if temperatures continue to increase. An increase in melting of the ice sheet would accelerate sea-level rise, an issue affecting potentially billions of people worldwide. The IST CDR will provide a convenient data set for modelers and for climatologists to track changes of the surface temperature of the ice sheet as a whole and of the individual drainage basins on the ice sheet. The daily and monthly maps will provide information on surface melt as well as "clear-sky" temperature. The CDR will be further validated by comparing results with automatic-weather station data and with satellite-derived surface-temperature products.

  6. Towards the intrahour forecasting of direct normal irradiance using sky-imaging data.

    Science.gov (United States)

    Nou, Julien; Chauvin, Rémi; Eynard, Julien; Thil, Stéphane; Grieu, Stéphane

    2018-04-01

    Increasing power plant efficiency through improved operation is key in the development of Concentrating Solar Power (CSP) technologies. To this end, one of the most challenging topics remains accurately forecasting the solar resource at a short-term horizon. Indeed, in CSP plants, production is directly impacted by both the availability and variability of the solar resource and, more specifically, by Direct Normal Irradiance (DNI). The present paper deals with a new approach to the intrahour forecasting (the forecast horizon [Formula: see text] is up to [Formula: see text] ahead) of DNI, taking advantage of the fact that this quantity can be split into two terms, i.e. clear-sky DNI and the clear sky index. Clear-sky DNI is forecasted from DNI measurements, using an empirical model (Ineichen and Perez, 2002) combined with a persistence of atmospheric turbidity. Moreover, in the framework of the CSPIMP (Concentrating Solar Power plant efficiency IMProvement) research project, PROMES-CNRS has developed a sky imager able to provide High Dynamic Range (HDR) images. So, regarding the clear-sky index, it is forecasted from sky-imaging data, using an Adaptive Network-based Fuzzy Inference System (ANFIS). A hybrid algorithm that takes inspiration from the classification algorithm proposed by Ghonima et al. (2012) when clear-sky anisotropy is known and from the hybrid thresholding algorithm proposed by Li et al. (2011) in the opposite case has been developed to the detection of clouds. Performance is evaluated via a comparative study in which persistence models - either a persistence of DNI or a persistence of the clear-sky index - are included. Preliminary results highlight that the proposed approach has the potential to outperform these models (both persistence models achieve similar performance) in terms of forecasting accuracy: over the test data used, RMSE (the Root Mean Square Error) is reduced of about [Formula: see text], with [Formula: see text], and [Formula: see

  7. Digital all-sky polarization imaging of partly cloudy skies.

    Science.gov (United States)

    Pust, Nathan J; Shaw, Joseph A

    2008-12-01

    Clouds reduce the degree of linear polarization (DOLP) of skylight relative to that of a clear sky. Even thin subvisual clouds in the "twilight zone" between clouds and aerosols produce a drop in skylight DOLP long before clouds become visible in the sky. In contrast, the angle of polarization (AOP) of light scattered by a cloud in a partly cloudy sky remains the same as in the clear sky for most cases. In unique instances, though, select clouds display AOP signatures that are oriented 90 degrees from the clear-sky AOP. For these clouds, scattered light oriented parallel to the scattering plane dominates the perpendicularly polarized Rayleigh-scattered light between the instrument and the cloud. For liquid clouds, this effect may assist cloud particle size identification because it occurs only over a relatively limited range of particle radii that will scatter parallel polarized light. Images are shown from a digital all-sky-polarization imager to illustrate these effects. Images are also shown that provide validation of previously published theories for weak (approximately 2%) polarization parallel to the scattering plane for a 22 degrees halo.

  8. Optical Polarization of Light from a Sorghum Canopy Measured Under Both a Clear and an Overcast Sky

    Science.gov (United States)

    Vanderbilt, Vern; Daughtry, Craig; Biehl, Larry; Dahlgren, Robert

    2014-01-01

    Introduction: We tested the hypothesis that the optical polarization of the light reflected by a sorghum canopy is due to a Fresnel-type redirection, by sorghum leaf surfaces, of light from an unpolarized light source, the sun or overcast sky, toward the measuring sensor. If it can be shown that the source of the polarization of the light scattered by the sorghum canopy is a first surface, Fresnel-type reflection, then removing this surface reflected light from measurements of canopy reflectance presumably would allow better insight into the biochemical processes such as photosynthesis and metabolism that occur in the interiors of sorghum canopy leaves. Methods: We constructed a tower 5.9m tall in the center of a homogenous sorghum field. We equipped two Barnes MMR radiometers with polarization analyzers on the number 1, 3 and 7 Landsat TM wavelength bands. Positioning the radiometers atop the tower, we collected radiance data in 44 view directions on two days, one day with an overcast sky and the other, clear and sunlit. From the radiance data we calculated the linear polarization of the reflected light for each radiometer wavelength channel and view direction. Results and Discussion: Our experimental results support our hypothesis, showing that the amplitude of the linearly polarized portion of the light reflected by the sorghum canopy varied dramatically with view azimuth direction under a point source, the sun, but the amplitude varied little with view azimuth direction under the hemispherical source, the overcast sky. Under the clear sky, the angle of polarization depended upon the angle of incidence of the sunlight on the leaf, while under the overcast sky the angle of polarization depended upon the zenith view angle. These results support a polarized radiation transport model of the canopy that is based upon a first surface, Fresnel reflection from leaves in the sorghum canopy.

  9. Estimation of clear sky hourly global solar radiation in Iraq

    Energy Technology Data Exchange (ETDEWEB)

    Al-Jumaily, Kais J.; Al-Zuhairi, Munya F.; Mahdi, Zahraa S. [Department of Atmospheric Sciences, College of Science, Al-Mustansiriyah University, Baghdad (Iraq)

    2012-07-01

    The availability of hourly solar radiation data is very important for applications utilizing solar energy and for climate and environmental aspects. The aim of this work is to use a simple model for estimating hourly global solar radiation under clear sky condition in Iraq. Calculations were compared with measurements obtained from local station in Baghdad city and from Meteosat satellite data for different locations in Iraq. The statistical test methods of the mean bias error (MBE), root mean square error (RMSE) and t-test were used to evaluate the performance of the model. Results indicated that a fairly good agreement exists between calculated and measured values for all locations in Iraq. Since the model is independent of any meteorological variable, it would be of a practical use for rural areas where no meteorological data are available.

  10. NOAA Climate Data Record (CDR) of Intersatellite Calibrated Clear-Sky HIRS Channel 12 Brightness Temperature, Version 2.6 (Superseded)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This NOAA Climate Data Record (CDR) of Inter-Satellite Calibrated Clear-Sky High Resolution Infrared Radiation Sounder (HIRS) Channel 12 brightness temperatures...

  11. Clear-Sky Probability for the August 21, 2017, Total Solar Eclipse Using the NREL National Solar Radiation Database

    Energy Technology Data Exchange (ETDEWEB)

    Habte, Aron M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Roberts, Billy J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kutchenreiter, Mark C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sengupta, Manajit [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wilcox, Steve [Solar Resource Solutions, LLC, Lakewood, CO (United States); Stoffel, Tom [Solar Resource Solutions, LLC, Lakewood, CO (United States)

    2017-07-21

    The National Renewable Energy Laboratory (NREL) and collaborators have created a clear-sky probability analysis to help guide viewers of the August 21, 2017, total solar eclipse, the first continent-spanning eclipse in nearly 100 years in the United States. Using cloud and solar data from NREL's National Solar Radiation Database (NSRDB), the analysis provides cloudless sky probabilities specific to the date and time of the eclipse. Although this paper is not intended to be an eclipse weather forecast, the detailed maps can help guide eclipse enthusiasts to likely optimal viewing locations. Additionally, high-resolution data are presented for the centerline of the path of totality, representing the likelihood for cloudless skies and atmospheric clarity. The NSRDB provides industry, academia, and other stakeholders with high-resolution solar irradiance data to support feasibility analyses for photovoltaic and concentrating solar power generation projects.

  12. Spectral model for clear sky atmospheric longwave radiation

    Science.gov (United States)

    Li, Mengying; Liao, Zhouyi; Coimbra, Carlos F. M.

    2018-04-01

    An efficient spectrally resolved radiative model is used to calculate surface downwelling longwave (DLW) radiation (0 ∼ 2500 cm-1) under clear sky (cloud free) conditions at the ground level. The wavenumber spectral resolution of the model is 0.01 cm-1 and the atmosphere is represented by 18 non-uniform plane-parallel layers with pressure in each layer determined on a pressure-based coordinate system. The model utilizes the most up-to-date (2016) HITRAN molecular spectral data for 7 atmospheric gases: H2O, CO2, O3, CH4, N2O, O2 and N2. The MT_CKD model is used to calculate water vapor and CO2 continuum absorption coefficients. Longwave absorption and scattering coefficients for aerosols are modeled using Mie theory. For the non-scattering atmosphere (aerosol free), the surface DLW agrees within 2.91% with mean values from the InterComparison of Radiation Codes in Climate Models (ICRCCM) program, with spectral deviations below 0.035 W cm m-2. For a scattering atmosphere with typical aerosol loading, the DLW calculated by the proposed model agrees within 3.08% relative error when compared to measured values at 7 climatologically diverse SURFRAD stations. This relative error is smaller than a calibrated parametric model regressed from data for those same 7 stations, and within the uncertainty (+/- 5 W m-2) of pyrgeometers commonly used for meteorological and climatological applications. The DLW increases by 1.86 ∼ 6.57 W m-2 when compared with aerosol-free conditions, and this increment decreases with increased water vapor content due to overlap with water vapor bands. As expected, the water vapor content at the layers closest to the surface contributes the most to the surface DLW, especially in the spectral region 0 ∼ 700 cm-1. Additional water vapor content (mostly from the lowest 1 km of the atmosphere) contributes to the spectral range of 400 ∼ 650 cm-1. Low altitude aerosols ( ∼ 3.46 km or less) contribute to the surface value of DLW mostly in the

  13. Preliminary Inter-Comparison between AHI, VIIRS and MODIS Clear-Sky Ocean Radiances for Accurate SST Retrievals

    Directory of Open Access Journals (Sweden)

    Xingming Liang

    2016-03-01

    Full Text Available Clear-sky brightness temperatures (BT in five bands of the Advanced Himawari Imager (AHI; flown onboard Himawari-8 satellite centered at 3.9, 8.6, 10.4, 11.2, and 12.3 µm (denoted by IR37, IR86, IR10, IR11, and IR12, respectively are used in the NOAA Advanced Clear-Sky Processor for Oceans (ACSPO sea surface temperature (SST retrieval system. Here, AHI BTs are preliminarily evaluated for stability and consistency with the corresponding VIIRS and MODIS BTs, using the sensor observation minus model simulation (O-M biases and corresponding double differences. The objective is to ensure accurate and consistent SST products from the polar and geo sensors, and to prepare for the launch of the GOES-R satellite in 2016. All five AHI SST bands are found to be largely in-family with their polar counterparts, but biased low relative to the VIIRS and MODIS (which, in turn, were found to be stable and consistent, except for Terra IR86, which is biased high by 1.5 K. The negative biases are larger in IR37 and IR12 (up to ~−0.5 K, followed by the three remaining longwave IR bands IR86, IR10, and IR11 (from −0.3 to −0.4 K. These negative biases may be in part due to the uncertainties in AHI calibration and characterization, although uncertainties in the coefficients of the Community Radiative Transfer Model (CRTM, used to generate the “M” term may also contribute. Work is underway to add AHI analyses in the NOAA Monitoring of IR Clear-Sky Radiances over Oceans for SST (MICROS system and improve AHI BTs by collaborating with the sensor calibration and CRTM teams. The Advanced Baseline Imager (ABI analyses will be also added in MICROS when GOES-R is launched in late 2016 and the ABI IR data become available.

  14. Daylight and energy implications for CIE standard skies

    International Nuclear Information System (INIS)

    Li, Danny H.W.

    2007-01-01

    Recently, the International Commission on Illumination (CIE) has adopted a range of 15 standard skies, which include the existing CIE overcast, very clear and cloudless polluted skies, covering the whole probable spectrum of usual skies found in the world. The traditional daylight factor (DF) approach with the calculations being based on an isotropic overcast sky, however, cannot cater to the dynamic variations in daylight luminance and illuminance as the sun's position changes under non-overcast skies. Currently, we propose a numerical procedure that considers the changes in the luminance of sky elements to predict the interior daylight illuminance under the 15 CIE standard skies. This paper evaluates the method by using a typical room with a large vertical glazing window facing north. The available daylight for the room at mean hourly sun positions in each month in terms of DF and illuminance levels were determined and compared with those based on a computer program, namely, RADIANCE. A modification to the ground reflected component was made when a well defined shadow was cast in front of the window facade. It is shown that the results estimated by the proposed approach are in reasonably good agreement with those produced from RADIANCE. The interior daylight and lighting energy consumption were also determined using the proposed and the traditional DF approaches. The findings reveal that daylighting designs using existing CIE overcast sky only would considerably underestimate the indoor daylight availability and electric lighting energy savings, especially under high design indoor illuminance settings

  15. Nocturnal infrared clear sky temperatures correlated with screen temperatures and GPS-derived PWV in southern Australia

    International Nuclear Information System (INIS)

    Maghrabi, A.; Clay, R.

    2011-01-01

    Highlights: → Model to calculate nocturnal sky temperature in mid-latitude site was developed. → New data acquired from new instrument. → Sky temperature correlated with both GPS-derived PWV and screen temperature. → The model was tested theoretically against MODTRAN software. → The performance of the model was compared against 20 independent models. - Abstract: Infrared (IR) clear sky temperatures (Tsky), screen level temperature (T) and Precipitable Water Vapour (PWV) were collected for a period of 2 years from a coastal region of southern Australia. IR sky temperatures were derived from simple infrared detectors, which have been developed by the authors for inexpensive monitoring of cloud cover, while data for PWV were obtained from Global Positioning Satellite (GPS) transmissions. Meteorological data were obtained from the Australian Bureau of Meteorology. Based on these data, statistical regression analyses between nocturnal Tsky and the T and PWV (one variable fit) were conducted. Direct proportional relationships between Tsky and T and between Tsky and PWV were found. The one variable fit was further optimized by applying the multiple regression fit between Tsky and both T and PWV. The resulting multilinear model was essentially unbiased, with a correlation coefficient (R 2 ) of 0.97, mean bias error (MBE) of -2.7 x 10 -5 deg. C, and root mean square error (RMSE) of about 1.6 o C. The performance of the multilinear model was tested against a 1-year independent data set. In this case, the predictability of the model was superior, with MBE and RMSE being 0.13 deg. C and 2.23 deg. C respectively. After correcting the daytime observations for the biases caused by solar heating of the detection system, the performance of this model in calculating the daytime measurements was tested and showed MBE and RMSE values of 1.3 deg. C and 2.5 deg. C, respectively. Additionally, twenty schemes from the literature were tested and assessed for predicting the

  16. distribution of hourly variability index of sky clearness

    African Journals Online (AJOL)

    Mgina

    Clouds affect the values of insolation for solar technology and other applications. To detect the presence of variability in the sky ... It appears that the site has great potential for application of solar technologies. INTRODUCTION. Knowledge about the .... for solar collectors-part 1. Thermal performance of glazed liquid heating.

  17. Performance characteristics of a perforated shadow band under clear sky conditions

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, Michael J. [School of Mechanical Engineering, University of KwaZulu-Natal, Durban (South Africa)

    2010-12-15

    A perforated, non-rotating shadow band is described for separating global solar irradiance into its diffuse and direct normal components using a single pyranometer. Whereas shadow bands are normally solid so as to occult the sensor of a pyranometer throughout the day, the proposed band has apertures cut from its circumference to intermittently expose the instrument sensor at preset intervals. Under clear sky conditions the device produces a saw tooth waveform of irradiance data from which it is possible to reconstruct separate global and diffuse curves. The direct normal irradiance may then be calculated giving a complete breakdown of the irradiance curves without need of a second instrument or rotating shadow band. This paper describes the principle of operation of the band and gives a mathematical model of its shading mask based on the results of an optical ray tracing study. An algorithm for processing the data from the perforated band system is described and evaluated. In an extended trial conducted at NREL's Solar Radiation Research Laboratory, the band coupled with a thermally corrected Eppley PSP produced independent curves for diffuse, global and direct normal irradiance with low mean bias errors of 5.6 W/m{sup 2}, 0.3 W/m{sup 2} and -2.6 W/m{sup 2} respectively, relative to collocated reference instruments. Random uncertainties were 9.7 W/m{sup 2} (diffuse), 17.3 W/m{sup 2} (global) and 19.0 W/m{sup 2} (direct). When the data processing algorithm was modified to include the ray trace model of sensor exposure, uncertainties increased only marginally, confirming the effectiveness of the model. Deployment of the perforated band system can potentially increase the accuracy of data from ground stations in predominantly sunny areas where instrumentation is limited to a single pyranometer. (author)

  18. Clear-sky irradiance simulation using GMAO products and its comparison to ground and CERES satellite observation

    Science.gov (United States)

    Ham, S. H.; Loeb, N. G.; Kato, S.; Rose, F. G.; Bosilovich, M. G.; Rutan, D. A.; Huang, X.; Collow, A.

    2017-12-01

    Global Modeling Assimilation Office (GMAO) GEOS assimilated datasets are used to describe temperature and humidity profiles in the Clouds and the Earth's Radiant Energy System (CERES) data processing. Given that advance versions of the assimilated data sets known as of Forward Processing (FP), FP Parallel (FPP), and Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) datasets are available, we examine clear-sky irradiance calculation to see if accuracy is improved with these newer versions of GMAO datasets when their temperature and humidity profiles are used in computing irradiances. Two older versions, GEOS-5.2.0 and GEOS-5.4.1 are used for producing, respectively, Ed3 and Ed4 CERES data products. For the evaluation, CERES-derived TOA irradiances and observed ground-based surface irradiances are compared with the computed irradiances for clear skies identified by Moderate Resolution Imaging Spectroradiometer (MODIS). Surface type dependent spectral emissivity is taken from an observationally-based monthly gridded emissivity dataset. TOA longwave (LW) irradiances computed with GOES-5.2.0 temperature and humidity profiles are biased low, up to -5 Wm-2, compared to CERES-derived TOA longwave irradiance over tropical oceans. In contrast, computed longwave irradiances agree well with CERES observations with the biases less than 2 W m-2 when GOES-5.4.1, FP v5.13, or MERRA-2 temperature and humidity are used. The negative biases of the TOA LW irradiance computed with GOES-5.2.0 appear to be related to a wet bias at 500-850 hPa layer. This indicates that if the input of CERES algorithm switches from GOES-5.2.0 to FP v5.13 or MERRA-2, the bias in clear-sky longwave TOA fluxes over tropical oceans is expected to be smaller. At surface, downward LW irradiances computed with FP v5.13 and MERRA-2 are biased low, up to -10 Wm-2, compared to ground observations over tropical oceans. The magnitude of the bias in the longwave surface irradiances

  19. Changes of diffuse UV-B radiation on clear sky days

    International Nuclear Information System (INIS)

    Kon, H.; Ichibayashi, R.; Matsuoka, N.

    2004-01-01

    Measurements of global and diffuse UV-B radiation have been carried out in Matsudo City (35.3 deg N, 139.9 deg E), Japan. Forty clear sky days were chosen and the annual variation of global and diffuse UV-B radiation was analyzed. The dependence of the diffuse component on visibility was also examined. The results are summarized as follows. 1. The maximum of daily global UV-B was beyond 40kJrec mE-2 daysup(-1) and was recorded in late July. The maximum of daily diffuse UV-B was recorded in early July. There was a tendency for the diffuse UV-B to be larger than the direct UV-B during a year in Matsudo. 2. The fraction of diffuse UV-B to global UV-B changed a lot each day. The observed minimum value of the fraction during a year was recorded in early August. 3. There was a tendency for the fraction of diffuse UV-B to global UV-B to decrease when visibility increased. 4. The diffuse components that change a lot each day were properly estimated by using the expected minimum fraction and visibility. Key words: Diffuse UV-B, Ultraviolet, UV-B, Visibility

  20. Broadband Direct UVA irradiance measurement for clear skies evaluated using a smartphone

    International Nuclear Information System (INIS)

    Igoe, D.; Parisi, A.V.

    2015-01-01

    UVA wavelengths (320-400 nm) have been implicated in recent studies to contribute to melanoma induction and skin photo-aging in humans and damage to plants. The use of smartphones in UVA observations is a way to supplement measurements made by traditional radiometric and spectro-radiometric technology. Although the smartphone image sensor is not capable of determining broadband UVA irradiances, these can be reconstructed from narrowband irradiances, which the smartphone, with narrowband and neutral density filters, can quantify with discrepancies not exceeding 5 %. Three models that reconstruct direct broadband clear sky UVA were developed from narrowband irradiances derived from smartphone image sensor pixel data with coefficients of determination of between 0.97 and 0.99. Reasonable accuracy and precision in determining the direct broadband UVA was maintained for observations made with solar zenith angles as high as 70 deg. . The developed method has the potential to increase the uptake of the measurement of broadband UVA irradiances. (authors)

  1. Measuring and prediction of global solar ultraviolet radiation (0295-0385 μ m) under clear and cloudless skies

    International Nuclear Information System (INIS)

    Wright, Jaime

    2008-01-01

    Values of global solar ultraviolet radiation were measured with an ultraviolet radiometer and also predicted with a atmospheric spectral model. The values obtained with the atmospheric spectral model, based physically, were analyzed and compared with experimental values measured in situ. Measurements were performed for different zenith angles in conditions of clear skies in Heredia, Costa Rica. The necessary input data include latitude, altitude, surface albedo, Earth-Sun distance, as well as atmospheric characteristics: atmospheric turbidity, precipitable water and atmospheric ozone. The comparison between measured and predicted values have been successful. (author) [es

  2. Infrared Sky Imager (IRSI) Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Morris, Victor R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-04-01

    The Infrared Sky Imager (IRSI) deployed at the Atmospheric Radiation Measurement (ARM) Climate Research Facility is a Solmirus Corp. All Sky Infrared Visible Analyzer. The IRSI is an automatic, continuously operating, digital imaging and software system designed to capture hemispheric sky images and provide time series retrievals of fractional sky cover during both the day and night. The instrument provides diurnal, radiometrically calibrated sky imagery in the mid-infrared atmospheric window and imagery in the visible wavelengths for cloud retrievals during daylight hours. The software automatically identifies cloudy and clear regions at user-defined intervals and calculates fractional sky cover, providing a real-time display of sky conditions.

  3. Carbon monoxide column retrieval for clear-sky and cloudy atmospheres : A full-mission data set from SCIAMACHY 2.3 μm reflectance measurements

    NARCIS (Netherlands)

    Borsdorff, Tobias; De Brugh, Joost Aan; Hu, Haili; Nédélec, Philippe; Aben, Ilse; Landgraf, Jochen

    2017-01-01

    We discuss the retrieval of carbon monoxide (CO) vertical column densities from clear-sky and cloud contaminated 2311-2338 nm reflectance spectra measured by the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) from January 2003 until the end of the mission in April

  4. Trends in total column ozone over Australia and New Zealand and its influence on clear-sky surface erythemal irradiance

    International Nuclear Information System (INIS)

    Bodeker, G. E.

    1995-01-01

    Australia and New Zealand are two of the countries closest to the Antarctic ozone depletion and may therefore be 'at risk' as a result of the associated increases in surface ultraviolet (UV) radiation. To investigate the possible impact of mid-latitude ozone decreases on surface erythemal irradiances, monthly mean total ozone has been calculated from daily total ozone mapping spectrometer data for 5 Australian cities (Canberra, Hobart, Melbourne, Perth and Sydney) and 3 New Zealand cities (Auckland, Christchurch and Wellington) from 1979 to 1992. These values have then been used as inputs to a single layer model to calculate noon clear-sky global UV irradiances and associated erythemal irradiances. In addition, the monthly mean ozone data have been modelled statistically for each location to reveal a long-term linear trend, an annual variation, a Quasi-Biennial Oscillation (QBO), a solar cycle component and a semi-annual (6 month) signal. Coefficients from these statistical models have been used to estimate monthly mean ozone and noon clear-sky erythemal irradiances to the year 2000 for each city. It is assumed that the rate of increase of stratospheric chlorine over the remainder of the century will remain constant. Given that there is some evidence that the rate of increase is decreasing, the results present here should be regarded as an upper limit. 33 refs., 7 tabs., 4 figs

  5. Regional and monthly and clear-sky aerosol direct radiative effect (and forcing derived from the GlobAEROSOL-AATSR satellite aerosol product

    Directory of Open Access Journals (Sweden)

    G. E. Thomas

    2013-01-01

    Full Text Available Using the GlobAEROSOL-AATSR dataset, estimates of the instantaneous, clear-sky, direct aerosol radiative effect and radiative forcing have been produced for the year 2006. Aerosol Robotic Network sun-photometer measurements have been used to characterise the random and systematic error in the GlobAEROSOL product for 22 regions covering the globe. Representative aerosol properties for each region were derived from the results of a wide range of literature sources and, along with the de-biased GlobAEROSOL AODs, were used to drive an offline version of the Met Office unified model radiation scheme. In addition to the mean AOD, best-estimate run of the radiation scheme, a range of additional calculations were done to propagate uncertainty estimates in the AOD, optical properties, surface albedo and errors due to the temporal and spatial averaging of the AOD fields. This analysis produced monthly, regional estimates of the clear-sky aerosol radiative effect and its uncertainty, which were combined to produce annual, global mean values of (−6.7 ± 3.9 W m−2 at the top of atmosphere (TOA and (−12 ± 6 W m−2 at the surface. These results were then used to give estimates of regional, clear-sky aerosol direct radiative forcing, using modelled pre-industrial AOD fields for the year 1750 calculated for the AEROCOM PRE experiment. However, as it was not possible to quantify the uncertainty in the pre-industrial aerosol loading, these figures can only be taken as indicative and their uncertainties as lower bounds on the likely errors. Although the uncertainty on aerosol radiative effect presented here is considerably larger than most previous estimates, the explicit inclusion of the major sources of error in the calculations suggest that they are closer to the true constraint on this figure from similar methodologies, and point to the need for more, improved estimates of both global aerosol loading and aerosol optical properties.

  6. Sky cover from MFRSR observations

    Directory of Open Access Journals (Sweden)

    E. Kassianov

    2011-07-01

    Full Text Available The diffuse all-sky surface irradiances measured at two nearby wavelengths in the visible spectral range and their modeled clear-sky counterparts are the main components of a new method for estimating the fractional sky cover of different cloud types, including cumuli. The performance of this method is illustrated using 1-min resolution data from a ground-based Multi-Filter Rotating Shadowband Radiometer (MFRSR. The MFRSR data are collected at the US Department of Energy Atmospheric Radiation Measurement (ARM Climate Research Facility (ACRF Southern Great Plains (SGP site during the summer of 2007 and represent 13 days with cumuli. Good agreement is obtained between estimated values of the fractional sky cover and those provided by a well-established independent method based on broadband observations.

  7. Polarization of sky light from a canopy atmosphere

    International Nuclear Information System (INIS)

    Hannay, J H

    2004-01-01

    Light from the clear sky is produced by the scattering of unpolarized sunlight by molecules of the atmosphere and is partially linearly polarized in the process. Singly scattered light, for instance, is fully polarized in viewing directions perpendicular to the sun direction and less and less so towards the parallel and antiparallel directions, where it is unpolarized. The true, multiple, scattering is much less tractable, but importantly different, changing the polarization pattern's topology by splitting the unpolarized directions into pairs. The underlying cause of this 'symmetry breaking' is that the atmosphere is 'wider' than it is deep. Simplifying as much as possible while retaining this feature leads to the caricature atmosphere analysed here: a flattened sheet atmosphere in the sky, a canopy. The multiple scattering is fully tractable and leads to a simple polarization pattern in the sky: the ellipses and hyperbolas of standard confocal ellipsoidal coordinates. The model realizes physically a mathematical pattern of polarization in terms of a complex function proposed by Berry, Dennis and Lee (2004 New J. Phys.6 162) as the simplest one which captures the topology

  8. Modulation of aerosol radiative forcing due to mixing state in clear and cloudy-sky: A case study from Delhi National Capital Region, India

    Science.gov (United States)

    Srivastava, Parul; Dey, Sagnik; Srivastava, Atul K.; Singh, Sachchidanand; Tiwari, Suresh; Agarwal, Poornima

    2016-04-01

    Aerosol properties change with the change in mixing state of aerosols and therefore it is a source of uncertainty in estimated aerosol radiative forcing (ARF) from observations or by models assuming a specific mixing state. The problem is important in the Indo-Gangetic Basin, Northern India, where various aerosol types mix and show strong seasonal variations. Quantifying the modulation of ARF by mixing state is hindered by lack of knowledge about proper aerosol composition. Hence, first a detailed chemical composition analysis of aerosols for Delhi National capital region (NCR) is carried out. Aerosol composition is arranged quantitatively into five major aerosol types - accumulation dust, coarse dust, water soluble (WS), water insoluble (WINS), and black carbon (BC) (directly measured by Athelometer). Eight different mixing cases - external mixing, internal mixing, and six combinations of core- shell mixing (BC over dust, WS over dust, WS over BC, BC over WS, WS over WINS, and BC over WINS; each of the combinations externally mixed with other species) have been considered. The spectral aerosol optical properties - extinction coefficient, single scattering albedo (SSA) and asymmetry parameter (g) for each of the mixing cases are calculated and finally 'clear-sky' and 'cloudy-sky' ARF at the top-of-the-atmosphere (TOA) and surface are estimated using a radiative transfer model. Comparison of surface-reaching flux for each of the cases with MERRA downward shortwave surface flux reveals the most likely mixing state. 'BC-WINS+WS+Dust' show least deviation relative to MERRA during the pre-monsoon (MAMJ) and monsoon (JAS) seasons and hence is the most probable mixing states. During the winter season (DJF), 'BC-Dust+WS+WINS' case shows the closest match with MERRA, while external mixing is the most probable mixing state in the post-monsoon season (ON). Lowest values for both TOA and surface 'clear-sky' ARF is observed for 'BC-WINS+WS+ Dust' mixing case. TOA ARF is 0.28±2

  9. Extracting Leaf Area Index by Sunlit Foliage Component from Downward-Looking Digital Photography under Clear-Sky Conditions

    Directory of Open Access Journals (Sweden)

    Yelu Zeng

    2015-10-01

    Full Text Available The development of near-surface remote sensing requires the accurate extraction of leaf area index (LAI from networked digital cameras under all illumination conditions. The widely used directional gap fraction model is more suitable for overcast conditions due to the difficulty to discriminate the shaded foliage from the shadowed parts of images acquired on sunny days. In this study, a new LAI extraction method by the sunlit foliage component from downward-looking digital photography under clear-sky conditions is proposed. In this method, the sunlit foliage component was extracted by an automated image classification algorithm named LAB2, the clumping index was estimated by a path length distribution-based method, the LAD and G function were quantified by leveled digital images and, eventually, the LAI was obtained by introducing a geometric-optical (GO model which can quantify the sunlit foliage proportion. The proposed method was evaluated at the YJP site, Canada, by the 3D realistic structural scene constructed based on the field measurements. Results suggest that the LAB2 algorithm makes it possible for the automated image processing and the accurate sunlit foliage extraction with the minimum overall accuracy of 91.4%. The widely-used finite-length method tends to underestimate the clumping index, while the path length distribution-based method can reduce the relative error (RE from 7.8% to 6.6%. Using the directional gap fraction model under sunny conditions can lead to an underestimation of LAI by (1.61; 55.9%, which was significantly outside the accuracy requirement (0.5; 20% by the Global Climate Observation System (GCOS. The proposed LAI extraction method has an RMSE of 0.35 and an RE of 11.4% under sunny conditions, which can meet the accuracy requirement of the GCOS. This method relaxes the required diffuse illumination conditions for the digital photography, and can be applied to extract LAI from downward-looking webcam images

  10. Field measurement of clear-sky solar irradiance in Badain Jaran Desert of Northwestern China

    International Nuclear Information System (INIS)

    Bi, Jianrong; Huang, Jianping; Fu, Qiang; Ge, Jinming; Shi, Jinsen; Zhou, Tian; Zhang, Wu

    2013-01-01

    . -- Highlights: ► We investigate the radiative properties of dust aerosols in Badain Jaran Desert. ► We correct thermal dome offset of diffuse irradiance using collocated pyrgeometer. ► A good radiative closure experiment is achieved. ► Heating rates in the whole atmosphere layer (0.1 K/day) under clear-sky is examined

  11. Short-Term Solar Irradiance Forecasts Using Sky Images and Radiative Transfer Model

    Directory of Open Access Journals (Sweden)

    Juan Du

    2018-05-01

    Full Text Available In this paper, we propose a novel forecast method which addresses the difficulty in short-term solar irradiance forecasting that arises due to rapidly evolving environmental factors over short time periods. This involves the forecasting of Global Horizontal Irradiance (GHI that combines prediction sky images with a Radiative Transfer Model (RTM. The prediction images (up to 10 min ahead are produced by a non-local optical flow method, which is used to calculate the cloud motion for each pixel, with consecutive sky images at 1 min intervals. The Direct Normal Irradiance (DNI and the diffuse radiation intensity field under clear sky and overcast conditions obtained from the RTM are then mapped to the sky images. Through combining the cloud locations on the prediction image with the corresponding instance of image-based DNI and diffuse radiation intensity fields, the GHI can be quantitatively forecasted for time horizons of 1–10 min ahead. The solar forecasts are evaluated in terms of root mean square error (RMSE and mean absolute error (MAE in relation to in-situ measurements and compared to the performance of the persistence model. The results of our experiment show that GHI forecasts using the proposed method perform better than the persistence model.

  12. Validation of a Climate-Data Record of the "Clear-Sky" Surface Temperature of the Greenland Ice Sheet

    Science.gov (United States)

    Hall, Dorothy K.; Box, Jason E.; Koenig, Lora S.; DiGirolamo, Nicolo E.; Comiso, Josefino C.; Shuman, Christopher A.

    2011-01-01

    Surface temperatures on the Greenland Ice Sheet have been studied on the ground, using automatic weather station (AWS) data from the Greenland-Climate Network (GC-Net), and from analysis of satellite sensor data. Using Advanced Very High Frequency Radiometer (AVHRR) weekly surface temperature maps, warming of the surface of the Greenland Ice Sheet has been documented since 1981. We extended and refined this record using higher-resolution Moderate-Resolution Imaging Spectroradiometer (MODIS) data from March 2000 to the present. We developed a daily and monthly climate-data record (CDR) of the "clear-sky" surface temperature of the Greenland Ice Sheet using an ice-surface temperature (1ST) algorithm developed for use with MODIS data. Validation of this CDR is ongoing. MODIS Terra swath data are projected onto a polar stereographic grid at 6.25-km resolution to develop binary, gridded daily and mean-monthly 1ST maps. Each monthly map also has a color-coded image map that is available to download. Also included with the monthly maps is an accompanying map showing number of days in the month that were used to calculate the mean-monthly 1ST. This is important because no 1ST decision is made by the algorithm for cells that are considered cloudy by the internal cloud mask, so a sufficient number of days must be available to produce a mean 1ST for each grid cell. Validation of the CDR consists of several facets: 1) comparisons between ISTs and in-situ measurements; 2) comparisons between ISTs and AWS data; and 3) comparisons of ISTs with surface temperatures derived from other satellite instruments such as the Thermal Emission and Reflection Radiometer (ASTER) and Enhanced Thematic Mapper Plus (ETM+). Previous work shows that Terra MODIS ISTs are about 3 C lower than in-situ temperatures measured at Summit Camp, during the winter of 2008-09 under clear skies. In this work we begin to compare surface temperatures derived from AWS data with ISTs from the MODIS CDR.

  13. Validation of the Two-Layer Model for Correcting Clear Sky Reflectance Near Clouds

    Science.gov (United States)

    Wen, Guoyong; Marshak, Alexander; Evans, K. Frank; Vamal, Tamas

    2014-01-01

    A two-layer model was developed in our earlier studies to estimate the clear sky reflectance enhancement near clouds. This simple model accounts for the radiative interaction between boundary layer clouds and molecular layer above, the major contribution to the reflectance enhancement near clouds for short wavelengths. We use LES/SHDOM simulated 3D radiation fields to valid the two-layer model for reflectance enhancement at 0.47 micrometer. We find: (a) The simple model captures the viewing angle dependence of the reflectance enhancement near cloud, suggesting the physics of this model is correct; and (b) The magnitude of the 2-layer modeled enhancement agree reasonably well with the "truth" with some expected underestimation. We further extend our model to include cloud-surface interaction using the Poisson model for broken clouds. We found that including cloud-surface interaction improves the correction, though it can introduced some over corrections for large cloud albedo, large cloud optical depth, large cloud fraction, large cloud aspect ratio. This over correction can be reduced by excluding scenes (10 km x 10km) with large cloud fraction for which the Poisson model is not designed for. Further research is underway to account for the contribution of cloud-aerosol radiative interaction to the enhancement.

  14. NIGHT SKY BRIGHTNESS ABOVE ZAGREB 2012.-2017.

    Directory of Open Access Journals (Sweden)

    Željko Andreić

    2018-01-01

    Full Text Available The night sky brightness at the RGN site (near the centre of Zagreb, Croatia was monitored form January 2012. to December 2017. The gathered data show that the average night sky brightness in this period did not change significantly, apart from differences caused by yearly variations in meteorological parameters. The nightly minima, maxima and mean values of the sky brightness do change considerably due to changes in meteorological conditions, often being between 2 and 3 magnitudes. The seasonal probability curves and histograms are constructed and are used to obtain additional information on the light pollution at the RGN site. They reveal that the night sky brightness clutters around two peaks, at about 15.0 mag/arcsec2 and at about 18.2 mag/arcsec2. The tendency to slightly lower brightness values in spring and summer can also be seen in the data. Two peaks correspond to cloudy and clear nights respectively, the difference in brightness between them being about 3 magnitudes. A crude clear/cloudy criterion can be defined too: the minimum between two peaks is around 16.7 mag/arcsec2. The brightness values smaller than thisare attributed to clear nights and vice-versa. Comparison with Vienna and Hong-Kong indicates that the light pollution of Zagreb is a few times larger.

  15. Sky Detection in Hazy Image.

    Science.gov (United States)

    Song, Yingchao; Luo, Haibo; Ma, Junkai; Hui, Bin; Chang, Zheng

    2018-04-01

    Sky detection plays an essential role in various computer vision applications. Most existing sky detection approaches, being trained on ideal dataset, may lose efficacy when facing unfavorable conditions like the effects of weather and lighting conditions. In this paper, a novel algorithm for sky detection in hazy images is proposed from the perspective of probing the density of haze. We address the problem by an image segmentation and a region-level classification. To characterize the sky of hazy scenes, we unprecedentedly introduce several haze-relevant features that reflect the perceptual hazy density and the scene depth. Based on these features, the sky is separated by two imbalance SVM classifiers and a similarity measurement. Moreover, a sky dataset (named HazySky) with 500 annotated hazy images is built for model training and performance evaluation. To evaluate the performance of our method, we conducted extensive experiments both on our HazySky dataset and the SkyFinder dataset. The results demonstrate that our method performs better on the detection accuracy than previous methods, not only under hazy scenes, but also under other weather conditions.

  16. Model for the angular distribution of sky radiance

    Energy Technology Data Exchange (ETDEWEB)

    Hooper, F C; Brunger, A P

    1979-08-01

    A flexible mathematical model is introduced which describes the radiance of the dome of the sky under various conditions. This three-component continuous distribution (TCCD) model is compounded by the superposition of three separate terms, the isotropic, circumsolar and horizon brightening terms, each representing the contribution of a particular sky characteristic. In use a particular sky condition is characterized by the values of the coefficients of each of these three terms, defining the distribution of the total diffuse component. The TCCD model has been demonstrated to fit both the normalized clear sky data and the normalized overcast sky data with an RMS error of about ten percent of the man overall sky radiance. By extension the model could describe variable or partly clouded sky conditions. The model can aid in improving the prediction of solar collector performance.

  17. Comparison of Microclimate Simulated weather data to ASHRAE Clear Sky Model and Measured Data

    Energy Technology Data Exchange (ETDEWEB)

    Bhandari, Mahabir S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-06-01

    In anticipation of emerging global urbanization and its impact on microclimate, a need exists to better understand and quantify microclimate effects on building energy use. Satisfaction of this need will require coordinated research of microclimate impacts on and from “human systems.” The Urban Microclimate and Energy Tool (Urban-MET) project seeks to address this need by quantifying and analyzing the relationships among climatic conditions, urban morphology, land cover, and energy use; and using these relationships to inform energy-efficient urban development and planning. Initial research will focus on analysis of measured and modeled energy efficiency of various building types in selected urban areas and temporal variations in energy use for different urban morphologies under different microclimatic conditions. In this report, we analyze the differences between microclimate weather data sets for the Oak Ridge National Laboratory campus produced by ENVI-met and Weather Research Forecast (WRF) models, the ASHRAE clear sky which defines the maximum amounts of solar radiation that can be expected, and measured data from a weather station on campus. Errors with climate variables and their impact on building energy consumption will be shown for the microclimate simulations to help prioritize future improvement for use in microclimate simulation impacts to energy use of buildings.

  18. Impact of Indoor Use of Wood on the Quality of Interior Ambiances under Overcast and Clear Skies: Case Study of the Eugene H. Kruger Building, Québec City

    Directory of Open Access Journals (Sweden)

    Hoda Jafarian

    2016-01-01

    Full Text Available This paper explores the potential of wood for improving environmental quality in interior spaces. In northern climate cities where overcast skies predominate, interior spaces may appear gloomy or dull, since natural light is white and uniform. Nevertheless it is observed that wooden surfaces tend to create warmer and brighter spaces under overcast sky conditions. The objectives of this research were twofold. The first was evaluating the quality of wooden spaces under two sky conditions in terms of color, brightness and contrast. The second objective was to investigate daylight quantity of wooden spaces under diffuse and clear sky conditions. The method involved on site-surveys using Photolux, a calibrated photoluminance meter. Data consist of calibrated digital images that were processed to analyze the quality of spaces based on brightness, contrast, and color. The Kruger Building, with its internal wooden architectural structure and decorative indoor panels, was chosen as a site study for this research. Conclusions suggest that knowing the effect of different sky conditions on wooden spaces can help architects and other professionals in designing more comfortable and efficient ambiances. More particularly, this research addresses issues related to the quantitative effects of wood on daylighting distribution, visual comfort and luminance diversity.

  19. Analysis of Ozone in Cloudy Versus Clear Sky Conditions

    Science.gov (United States)

    Strode, Sarah; Douglass, Anne; Ziemke, Jerald

    2016-01-01

    Convection impacts ozone concentrations by transporting ozone vertically and by lofting ozone precursors from the surface, while the clouds and lighting associated with convection affect ozone chemistry. Observations of the above-cloud ozone column (Ziemke et al., 2009) derived from the OMI instrument show geographic variability, and comparison of the above-cloud ozone with all-sky tropospheric ozone columns from OMI indicates important regional differences. We use two global models of atmospheric chemistry, the GMI chemical transport model (CTM) and the GEOS-5 chemistry climate model, to diagnose the contributions of transport and chemistry to observed differences in ozone between areas with and without deep convection, as well as differences in clean versus polluted convective regions. We also investigate how the above-cloud tropospheric ozone from OMI can provide constraints on the relationship between ozone and convection in a free-running climate simulation as well as a CTM.

  20. Estimation of Diurnal Cycle of Land Surface Temperature at High Temporal and Spatial Resolution from Clear-Sky MODIS Data

    Directory of Open Access Journals (Sweden)

    Si-Bo Duan

    2014-04-01

    Full Text Available The diurnal cycle of land surface temperature (LST is an important element of the climate system. Geostationary satellites can provide the diurnal cycle of LST with low spatial resolution and incomplete global coverage, which limits its applications in some studies. In this study, we propose a method to estimate the diurnal cycle of LST at high temporal and spatial resolution from clear-sky MODIS data. This method was evaluated using the MSG-SEVIRI-derived LSTs. The results indicate that this method fits the diurnal cycle of LST well, with root mean square error (RMSE values less than 1 K for most pixels. Because MODIS provides at most four observations per day at a given location, this method was further evaluated using only four MSG-SEVIRI-derived LSTs corresponding to the MODIS overpass times (10:30, 13:30, 22:30, and 01:30 local solar time. The results show that the RMSE values using only four MSG-SEVIRI-derived LSTs are approximately two times larger than those using all LSTs. The spatial distribution of the modeled LSTs at the MODIS pixel scale is presented from 07:00 to 05:00 local solar time of the next day with an increment of 2 hours. The diurnal cycle of the modeled LSTs describes the temporal evolution of the LSTs at the MODIS pixel scale.

  1. Sky luminosity for Rio de Janeiro City - Brazil

    International Nuclear Information System (INIS)

    Corbella, O.D.

    1995-12-01

    This paper presents sky luminosity data for Rio de Janeiro City, useful to be used in daylighting design in architecture. The data are presented as monthly graphics that correlate sunshine-hours with the frequency of occurrence during the day of a specific type of sky, that would present one of five defined characteristics (among clear and overcast sky). These results were derived from the knowledge of daily solar radiation and sunshine-hours data, for every day for a twelve year period. (author). 10 refs, 13 figs, 16 tabs

  2. Clear-Sky Longwave Irradiance at the Earth's Surface--Evaluation of Climate Models.

    Science.gov (United States)

    Garratt, J. R.

    2001-04-01

    An evaluation of the clear-sky longwave irradiance at the earth's surface (LI) simulated in climate models and in satellite-based global datasets is presented. Algorithm-based estimates of LI, derived from global observations of column water vapor and surface (or screen air) temperature, serve as proxy `observations.' All datasets capture the broad zonal variation and seasonal behavior in LI, mainly because the behavior in column water vapor and temperature is reproduced well. Over oceans, the dependence of annual and monthly mean irradiance upon sea surface temperature (SST) closely resembles the observed behavior of column water with SST. In particular, the observed hemispheric difference in the summer minus winter column water dependence on SST is found in all models, though with varying seasonal amplitudes. The analogous behavior in the summer minus winter LI is seen in all datasets. Over land, all models have a more highly scattered dependence of LI upon surface temperature compared with the situation over the oceans. This is related to a much weaker dependence of model column water on the screen-air temperature at both monthly and annual timescales, as observed. The ability of climate models to simulate realistic LI fields depends as much on the quality of model water vapor and temperature fields as on the quality of the longwave radiation codes. In a comparison of models with observations, root-mean-square gridpoint differences in mean monthly column water and temperature are 4-6 mm (5-8 mm) and 0.5-2 K (3-4 K), respectively, over large regions of ocean (land), consistent with the intermodel differences in LI of 5-13 W m2 (15-28 W m2).

  3. "Radiative Closure Studies for Clear Skies During the ARM 2003 Aerosol Intensive Observation Period"

    Energy Technology Data Exchange (ETDEWEB)

    J. J. Michalsky, G. P. Anderson, J. Barnard, J. Delamere, C. Gueymard, S. Kato, P. Kiedron, A. McComiskey, and P. Ricchiazzi

    2006-04-01

    The Department of Energy's Atmospheric Radiation Measurement (ARM) program sponsored a large intensive observation period (IOP) to study aerosol during the month of May 2003 around the Southern Great Plains (SGP) Climate Research Facility (CRF) in north central Oklahoma. Redundant measurements of aerosol optical properties were made using different techniques at the surface as well as in vertical profile with sensors aboard two aircraft. One of the principal motivations for this experiment was to resolve the disagreement between models and measurements of diffuse horizontal broadband shortwave irradiance at the surface, especially for modest aerosol loading. This paper focuses on using the redundant aerosol and radiation measurements during this IOP to compare direct beam and diffuse horizontal broadband shortwave irradiance measurements and models at the surface for a wide range of aerosol cases that occurred during 30 clear-sky periods on 13 days of May 2003. Models and measurements are compared over a large range of solar-zenith angles. Six different models are used to assess the relative agreement among them and the measurements. Better agreement than previously achieved appears to be the result of better specification of input parameters and better measurements of irradiances than in prior studies. Biases between modeled and measured direct irradiances are less than 1%, and biases between modeled and measured diffuse irradiances are less than 2%.

  4. Accuracy of the hypothetical sky-polarimetric Viking navigation versus sky conditions: revealing solar elevations and cloudinesses favourable for this navigation method

    Science.gov (United States)

    Száz, Dénes; Farkas, Alexandra; Barta, András; Kretzer, Balázs; Blahó, Miklós; Egri, Ádám; Szabó, Gyula; Horváth, Gábor

    2017-09-01

    According to Thorkild Ramskou's theory proposed in 1967, under overcast and foggy skies, Viking seafarers might have used skylight polarization analysed with special crystals called sunstones to determine the position of the invisible Sun. After finding the occluded Sun with sunstones, its elevation angle had to be measured and its shadow had to be projected onto the horizontal surface of a sun compass. According to Ramskou's theory, these sunstones might have been birefringent calcite or dichroic cordierite or tourmaline crystals working as polarizers. It has frequently been claimed that this method might have been suitable for navigation even in cloudy weather. This hypothesis has been accepted and frequently cited for decades without any experimental support. In this work, we determined the accuracy of this hypothetical sky-polarimetric Viking navigation for 1080 different sky situations characterized by solar elevation θ and cloudiness ρ, the sky polarization patterns of which were measured by full-sky imaging polarimetry. We used the earlier measured uncertainty functions of the navigation steps 1, 2 and 3 for calcite, cordierite and tourmaline sunstone crystals, respectively, and the newly measured uncertainty function of step 4 presented here. As a result, we revealed the meteorological conditions under which Vikings could have used this hypothetical navigation method. We determined the solar elevations at which the navigation uncertainties are minimal at summer solstice and spring equinox for all three sunstone types. On average, calcite sunstone ensures a more accurate sky-polarimetric navigation than tourmaline and cordierite. However, in some special cases (generally at 35° ≤ θ ≤ 40°, 1 okta ≤ ρ ≤ 6 oktas for summer solstice, and at 20° ≤ θ ≤ 25°, 0 okta ≤ ρ ≤ 4 oktas for spring equinox), the use of tourmaline and cordierite results in smaller navigation uncertainties than that of calcite. Generally, under clear or less cloudy

  5. 77 FR 66196 - Self-Regulatory Organizations; Options Clearing Corporation; Order Approving Proposed Rule Change...

    Science.gov (United States)

    2012-11-02

    ... Accounting Principles (``GAAP''). Canadian clearing members that use Form 1 report the same, and in some... Organizations; Options Clearing Corporation; Order Approving Proposed Rule Change Relating to Financial... financial reporting by Canadian clearing members to reflect the Investment Industry Regulatory Organization...

  6. 76 FR 2737 - Self-Regulatory Organizations; National Securities Clearing Corporation; Order Approving Proposed...

    Science.gov (United States)

    2011-01-14

    ... SECURITIES AND EXCHANGE COMMISSION [Release No. 34-63668; File No. SR-NSCC-2010-09] Self-Regulatory Organizations; National Securities Clearing Corporation; Order Approving Proposed Rule Change... Facility January 6, 2011. I. Introduction On August 30, 2010, the National Securities Clearing Corporation...

  7. 78 FR 69168 - Self-Regulatory Organizations; National Securities Clearing Corporation; Order Approving Proposed...

    Science.gov (United States)

    2013-11-18

    ... approve a proposed rule change of a self-regulatory organization if it finds that such proposed rule... SECURITIES AND EXCHANGE COMMISSION [Release No. 34-70848; File No. SR-NSCC-2013-10] Self-Regulatory Organizations; National Securities Clearing Corporation; Order Approving Proposed Rule Change To...

  8. Method for validating cloud mask obtained from satellite measurements using ground-based sky camera.

    Science.gov (United States)

    Letu, Husi; Nagao, Takashi M; Nakajima, Takashi Y; Matsumae, Yoshiaki

    2014-11-01

    Error propagation in Earth's atmospheric, oceanic, and land surface parameters of the satellite products caused by misclassification of the cloud mask is a critical issue for improving the accuracy of satellite products. Thus, characterizing the accuracy of the cloud mask is important for investigating the influence of the cloud mask on satellite products. In this study, we proposed a method for validating multiwavelength satellite data derived cloud masks using ground-based sky camera (GSC) data. First, a cloud cover algorithm for GSC data has been developed using sky index and bright index. Then, Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data derived cloud masks by two cloud-screening algorithms (i.e., MOD35 and CLAUDIA) were validated using the GSC cloud mask. The results indicate that MOD35 is likely to classify ambiguous pixels as "cloudy," whereas CLAUDIA is likely to classify them as "clear." Furthermore, the influence of error propagations caused by misclassification of the MOD35 and CLAUDIA cloud masks on MODIS derived reflectance, brightness temperature, and normalized difference vegetation index (NDVI) in clear and cloudy pixels was investigated using sky camera data. It shows that the influence of the error propagation by the MOD35 cloud mask on the MODIS derived monthly mean reflectance, brightness temperature, and NDVI for clear pixels is significantly smaller than for the CLAUDIA cloud mask; the influence of the error propagation by the CLAUDIA cloud mask on MODIS derived monthly mean cloud products for cloudy pixels is significantly smaller than that by the MOD35 cloud mask.

  9. Impact of elevated CO2 concentration on dynamics of leaf photosynthesis in Fagus sylvatica is modulated by sky conditions.

    Science.gov (United States)

    Urban, Otmar; Klem, Karel; Holišová, Petra; Šigut, Ladislav; Šprtová, Mirka; Teslová-Navrátilová, Petra; Zitová, Martina; Špunda, Vladimír; Marek, Michal V; Grace, John

    2014-02-01

    It has been suggested that atmospheric CO2 concentration and frequency of cloud cover will increase in future. It remains unclear, however, how elevated CO2 influences photosynthesis under complex clear versus cloudy sky conditions. Accordingly, diurnal changes in photosynthetic responses among beech trees grown at ambient (AC) and doubled (EC) CO2 concentrations were studied under contrasting sky conditions. EC stimulated the daily sum of fixed CO2 and light use efficiency under clear sky. Meanwhile, both these parameters were reduced under cloudy sky as compared with AC treatment. Reduction in photosynthesis rate under cloudy sky was particularly associated with EC-stimulated, xanthophyll-dependent thermal dissipation of absorbed light energy. Under clear sky, a pronounced afternoon depression of CO2 assimilation rate was found in sun-adapted leaves under EC compared with AC conditions. This was caused in particular by stomata closure mediated by vapour pressure deficit. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  10. Accuracy of the hypothetical sky-polarimetric Viking navigation versus sky conditions: revealing solar elevations and cloudinesses favourable for this navigation method.

    Science.gov (United States)

    Száz, Dénes; Farkas, Alexandra; Barta, András; Kretzer, Balázs; Blahó, Miklós; Egri, Ádám; Szabó, Gyula; Horváth, Gábor

    2017-09-01

    According to Thorkild Ramskou's theory proposed in 1967, under overcast and foggy skies, Viking seafarers might have used skylight polarization analysed with special crystals called sunstones to determine the position of the invisible Sun. After finding the occluded Sun with sunstones, its elevation angle had to be measured and its shadow had to be projected onto the horizontal surface of a sun compass. According to Ramskou's theory, these sunstones might have been birefringent calcite or dichroic cordierite or tourmaline crystals working as polarizers. It has frequently been claimed that this method might have been suitable for navigation even in cloudy weather. This hypothesis has been accepted and frequently cited for decades without any experimental support. In this work, we determined the accuracy of this hypothetical sky-polarimetric Viking navigation for 1080 different sky situations characterized by solar elevation θ and cloudiness ρ , the sky polarization patterns of which were measured by full-sky imaging polarimetry. We used the earlier measured uncertainty functions of the navigation steps 1, 2 and 3 for calcite, cordierite and tourmaline sunstone crystals, respectively, and the newly measured uncertainty function of step 4 presented here. As a result, we revealed the meteorological conditions under which Vikings could have used this hypothetical navigation method. We determined the solar elevations at which the navigation uncertainties are minimal at summer solstice and spring equinox for all three sunstone types. On average, calcite sunstone ensures a more accurate sky-polarimetric navigation than tourmaline and cordierite. However, in some special cases (generally at 35° ≤  θ  ≤ 40°, 1 okta ≤  ρ  ≤ 6 oktas for summer solstice, and at 20° ≤  θ  ≤ 25°, 0 okta ≤  ρ  ≤ 4 oktas for spring equinox), the use of tourmaline and cordierite results in smaller navigation uncertainties than that of calcite

  11. A night sky model.

    Science.gov (United States)

    Erpylev, N. P.; Smirnov, M. A.; Bagrov, A. V.

    A night sky model is proposed. It includes different components of light polution, such as solar twilight, moon scattered light, zodiacal light, Milky Way, air glow and artificial light pollution. The model is designed for calculating the efficiency of astronomical installations.

  12. 77 FR 40394 - Self-Regulatory Organizations; The Options Clearing Corporation; Order Approving Proposed Rule...

    Science.gov (United States)

    2012-07-09

    ... SECURITIES AND EXCHANGE COMMISSION [Release No. 34-67333; File No. SR-OCC-2012-07] Self-Regulatory Organizations; The Options Clearing Corporation; Order Approving Proposed Rule Change Relating to Adjustment... to approve a proposed rule change of a self-regulatory organization if it finds that such proposed...

  13. Infrared Sky Surveys

    Science.gov (United States)

    Price, Stephan D.

    2009-02-01

    A retrospective is given on infrared sky surveys from Thomas Edison’s proposal in the late 1870s to IRAS, the first sensitive mid- to far-infrared all-sky survey, and the mid-1990s experiments that filled in the IRAS deficiencies. The emerging technology for space-based surveys is highlighted, as is the prominent role the US Defense Department, particularly the Air Force, played in developing and applying detector and cryogenic sensor advances to early mid-infrared probe-rocket and satellite-based surveys. This technology was transitioned to the infrared astronomical community in relatively short order and was essential to the success of IRAS, COBE and ISO. Mention is made of several of the little known early observational programs that were superseded by more successful efforts.

  14. A lobster-eye on the x-ray sky

    International Nuclear Information System (INIS)

    Peele, A. G.; Zhang, W.; Gendreau, K. C.; Petre, R.; White, N. E.

    1999-01-01

    We propose an x-ray all-sky monitor for the International Space Station (ISS) that will be ten times more sensitive than past monitors and that opens up a new band of the soft x-ray spectrum (0.1 -3.0 keV) for study. Taking advantage of the power telemetry and space available on the ISS we can use a telescope geometry and detectors that will provide better than 4 arc minute resolution of the entire sky in a 1.5 hr duty cycle. To achieve this sensitivity and resolution we use focusing optics based on the lobster-eye geometry. We propose two approaches to the construction of the optics. The first method, well within the reach of existing technology, is to approximate the lobster-eye geometry by building crossed arrays of planar reflectors, this gives great control over the reflecting surface but is limited in terms of resolution at the baseline 4 arc minute level. The second method is to use microchannel plates: this technology has the potential to greatly exceed the baseline resolution and sensitivity but is yet to be fully demonstrated. A simultaneous development of both approaches with selection of the superior candidate at the end of the development phase is suggested. The instrument is made of a number of modules based on a 2x2 cooled CCD detector array that covers an area of 6x6 cm 2 at the focal plane. Using optics with a radius of curvature of 0.75 m this gives each module a field of view of 9 deg. x 9 deg. The modular approach gives us enormous flexibility in terms of physical arrangement on the ISS so that we may take advantage of clear lines of sight and also in terms of built-in redundancy. We estimate that ∼50 such modules give us instantaneous coverage of 1/10 of the sky. The scientific case for this mission is almost too broad to state here. The instrument we describe will allow investigation of the long term light curves of thousands of AGN, it will detect thousands of transients, including GRBs and type II supernova, and the stellar coronae of

  15. The Rainbow Sky

    CERN Document Server

    Buick, Tony

    2010-01-01

    The world is full of color, from the blue ocean and the yellow daffodils and sunflowers in green carpeted meadows to the majestic purple mountains in the distance and brightly hued coral reefs off the edges of tropical coasts. But what is color, exactly? Why do we see things in different colors? Do we all see the same colors? Like the surface of our planet, the sky above us offers us an endless palette of color, a visual feast for the eyes. Besides atmospheric phenomena such as sunsets and rainbows, there are the many varied worlds of the Solar System, which we can spy through our telescopes, with their subtle colorings of beige and blue and green. Faraway star systems have suns that come in shades ranging from red and yellow to blue and white. Scientists even often use "false colors" to enhance the features of images they take of structures, such as the rings of Saturn and Jupiter’s clouds. This book, with its clear explanations of what makes the sky such a colorful place and in its great wealth of picture...

  16. Cloud and radiance measurements with the VIS/NIR Daylight Whole Sky Imager at Lindenberg (Germany)

    Energy Technology Data Exchange (ETDEWEB)

    Feister, U. [Deutscher Wetterdienst, Meteorologisches Observatorium Lindenberg (Germany); Shields, J. [Scripps Inst. of Oceanography, Univ. of California, San Diego (United States)

    2005-10-01

    Ground-based cloud data acquired with the whole sky imager (WSI) are analyzed in relation to measurements of solar radiation performed at the Lindenberg Meteorological Observatory. Cloud fractions derived by the cloud detection algorithm from WSI images acquired during daylight hours between 2002 and 2004 are compared with conventional cloud observations for the two sites Potsdam and Lindenberg, and also with ceilometer data of cloud-base heights at Lindenberg. The comparison statistics are discussed in the context of different principles of measurement. A few case studies illustrate the strong scattering effect of clouds on solar radiance and irradiance measured at the ground in different spectral regions. Particularly clouds close to the apparent position of the sun lead to strong enhancements of solar diffuse irradiance incident on horizontal planes and hemispheres that substantially exceed corresponding clear-sky values. Irradiances derived from WSI sky radiance fields are shown in comparison to pyranometer data of diffuse irradiance and radiative transfer model calculations performed for clear sky conditions. Examples of spectral sky radiances with moving contrails illustrate the significant enhancement the contrails have compared to clear sky, even though they may have a relatively small direct effect on global irradiance values. As contrails are observed at Lindenberg for about 18 to 19% of daylight hours, and part of them become clouds, the indirect impact of these changes on solar irradiance received at the ground may not be negligible. (orig.)

  17. The New Progress of the Starry Sky Project of China

    Science.gov (United States)

    Wang, Xiaohua

    2015-08-01

    Since the 28th General Assembly of IAU, the SSPC team made new progress:1. Enhanced the function of the SSPC team-- Established the contact with IAU C50, IUCN Dark Skies Advisory Group, AWB and IDA,and undertakes the work of the IDA Beijing Chapter.-- Got supports from China’s National Astronomical Observatories, Beijing Planetarium, and Shanghai Science and Technology Museum.-- Signed cooperation agreements with Lighting Research Center, English Education Group and law Firm; formed the team force.2. Put forward a proposal to national top institutionThe SSPC submitted the first proposal about dark sky protection to the Chinese People’s Political Consultative Conference.3. Introduced the Criteria and Guideline of dark sky protectionThe SSPC team translated 8 documents of IDA, and provided a reference basis for Chinese dark sky protection.4. Actively establish dark sky places-- Plan a Dark Sky Reserve around Ali astronomical observatory (5,100m elevation) in Tibet. China’s Xinhua News Agency released the news.-- Combining with Hangcuo Lake, a National Natural Reserve and Scenic in Tibet, to plan and establish the Dark Sky Park.-- Cooperated with Shandong Longgang Tourism Group to construct the Dream Sky Theme Park in the suburbs of Jinan city.In the IYL 2015, the SSPC is getting further development:First, make dark sky protection enter National Ecological Strategy of “Beautiful China”. We call on: “Beautiful China” needs “Beautiful Night Sky” China should care the shared starry sky, and left this resource and heritage for children.Second, hold “Cosmic Light” exhibition in Shanghai Science and Technology Museum on August.Third, continue to establish Dark Sky Reserve, Park and Theme Park. We want to make these places become the bases of dark sky protection, astronomical education and ecological tourism, and develop into new cultural industry.Fourth, actively join international cooperation.Now, “Blue Sky, White Cloud and Starry Sky “have become

  18. Impact of elevated CO2 concentration on dynamics of leaf photosynthesis in Fagus sylvatica is modulated by sky conditions

    International Nuclear Information System (INIS)

    Urban, Otmar; Klem, Karel; Holišová, Petra; Šigut, Ladislav; Šprtová, Mirka; Teslová-Navrátilová, Petra; Zitová, Martina; Špunda, Vladimír; Marek, Michal V.; Grace, John

    2014-01-01

    It has been suggested that atmospheric CO 2 concentration and frequency of cloud cover will increase in future. It remains unclear, however, how elevated CO 2 influences photosynthesis under complex clear versus cloudy sky conditions. Accordingly, diurnal changes in photosynthetic responses among beech trees grown at ambient (AC) and doubled (EC) CO 2 concentrations were studied under contrasting sky conditions. EC stimulated the daily sum of fixed CO 2 and light use efficiency under clear sky. Meanwhile, both these parameters were reduced under cloudy sky as compared with AC treatment. Reduction in photosynthesis rate under cloudy sky was particularly associated with EC-stimulated, xanthophyll-dependent thermal dissipation of absorbed light energy. Under clear sky, a pronounced afternoon depression of CO 2 assimilation rate was found in sun-adapted leaves under EC compared with AC conditions. This was caused in particular by stomata closure mediated by vapour pressure deficit. -- Highlights: • Sky conditions affect the relative impact of elevated CO 2 on photosynthesis. • Cloudy skies reduce light use efficiency and carbon gain when CO 2 is elevated. • Stimulation of photosynthesis by high CO 2 may decline with increasing cloud cover. • High CO 2 leads to marked afternoon photosynthesis depression in sun-adapted leaves. -- The stimulatory effect of elevated CO 2 concentration on photosynthetic carbon assimilation can be expected to diminish as cloud cover increases

  19. 78 FR 24257 - Self-Regulatory Organizations; The Options Clearing Corporation; Order Approving Proposed Rule...

    Science.gov (United States)

    2013-04-24

    ... positions are in-the- money or out-of-the-money. Volume, like open interest, is a measure of a Clearing... demands on OCC's services and facilities that are not captured by the current methodology. IV. Conclusion... Organizations; The Options Clearing Corporation; Order Approving Proposed Rule Change To Implement a Revised...

  20. A clear-sky hyperspectral closure study for MERRA-2 and ERA-interim reanalyses

    Science.gov (United States)

    Chen, X.; Huang, X.; Loeb, N. G.; Dong, X.; Xi, B.; Dolinar, E. K.; Bosilovich, M. G.; Kato, S.; Smith, W. L., Jr.; Stackhouse, P. W., Jr.

    2017-12-01

    We carried out a clear-sky radiance closure study to compare four sets of synthetic AIRS spectra to 51 AIRS L1 spectra over the ARM Southern Great Plains (SGP) site. The AIRS observations were made when the ARM SGP cloud radar identified cloud free situation for 50-km region within the SGP site. Four sets of synthetic AIRS spectra are calculated using collocated atmospheric profiles from ARM SGP sounding, AIRS L2 retrievals, MERRA-2 and ECMWF ERA-Interim reanalyses. Only channels that are sensitive to temperature, CO2 and water vapor and not to other trace gases are selected for study. The selected channels are further divided into different groups according to their sensitivities to the emission from different vertical levels and to H2O and CO2, respectively. Observed and synthetic radiances of each group are then examined. For synthetic spectra using the AIRS L2 retrievals or the ARM SGP sounding profiles, the brightness temperature (BT) differences between synthetic and observed ones are within ±0.5 K or even smaller, for all groups and for all four seasons. For MERRA-2 and ECMWF-interim reanalyses, the BT differences from observations for each CO2 group are generally within ±0.5 K, indicating good agreements with respect to temperature profiles in the reanalyses. The BT differences for H2O groups are all negative, ranging from -0.5K to -1.5K. The largest BT difference is -1.5K for H2O channels peaking at 400-200 hPa. Such BT difference is persistent when the synthetic radiances based on reanalyses are compared with observed ones for the entire zone of 30°N-40°N. These comparisons imply that the reanalyses can represent the temperature profile well but there is persistent wet bias in the reanalyses, especially for the upper troposphere. The water vapor at 400-200 hPa in reanalyses needs to be adjusted by about -0.01 g/kg in order to reach agreement with the observed radiances.

  1. 77 FR 59231 - Self-Regulatory Organizations; The Options Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2012-09-26

    ... proposed changes to OCC's Rules provide for the calculation of margin for segregated futures customer... the Commission, and all written communications relating to the proposed rule change between the... Organizations; The Options Clearing Corporation; Notice of Filing of Proposed Rule Change Relating to the...

  2. SKY BRIGHTNESS AND TRANSPARENCY IN THE i-BAND AT DOME A, ANTARCTICA

    International Nuclear Information System (INIS)

    Zou Hu; Zhou Xu; Jiang Zhaoji; Hu Jingyao; Ma Jun; Ashley, M. C. B.; Luong-Van, D. M.; Storey, J. W. V.; Cui Xiangqun; Feng Longlong; Gong Xuefei; Kulesa, C. A.; Lawrence, J. S.; Liu Genrong; Moore, A. M.; Pennypacker, C. R.; Travouillon, T.; Qin Weijia; Sun Bo; Shang Zhaohui

    2010-01-01

    The i-band observing conditions at Dome A on the Antarctic plateau have been investigated using data acquired during 2008 with the Chinese Small Telescope Array. The sky brightness, variations in atmospheric transparency, cloud cover, and the presence of aurorae are obtained from these images. The median sky brightness of moonless clear nights is 20.5 mag arcsec -2 in the SDSS i band at the south celestial pole (which includes a contribution of about 0.06 mag from diffuse Galactic light). The median over all Moon phases in the Antarctic winter is about 19.8 mag arcsec -2 . There were no thick clouds in 2008. We model contributions of the Sun and the Moon to the sky background to obtain the relationship between the sky brightness and transparency. Aurorae are identified by comparing the observed sky brightness to the sky brightness expected from this model. About 2% of the images are affected by relatively strong aurorae.

  3. Automated exploitation of sky polarization imagery.

    Science.gov (United States)

    Sadjadi, Firooz A; Chun, Cornell S L

    2018-03-10

    We propose an automated method for detecting neutral points in the sunlit sky. Until now, detecting these singularities has been done manually. Results are presented that document the application of this method on a limited number of polarimetric images of the sky captured with a camera and rotating polarizer. The results are significant because a method for automatically detecting the neutral points may aid in the determination of the solar position when the sun is obscured and may have applications in meteorology and pollution detection and characterization.

  4. From Near-Neutral to Strongly Stratified: Adequately Modelling the Clear-Sky Nocturnal Boundary Layer at Cabauw.

    Science.gov (United States)

    Baas, P; van de Wiel, B J H; van der Linden, S J A; Bosveld, F C

    2018-01-01

    The performance of an atmospheric single-column model (SCM) is studied systematically for stably-stratified conditions. To this end, 11 years (2005-2015) of daily SCM simulations were compared to observations from the Cabauw observatory, The Netherlands. Each individual clear-sky night was classified in terms of the ambient geostrophic wind speed with a [Formula: see text] bin-width. Nights with overcast conditions were filtered out by selecting only those nights with an average net radiation of less than [Formula: see text]. A similar procedure was applied to the observational dataset. A comparison of observed and modelled ensemble-averaged profiles of wind speed and potential temperature and time series of turbulent fluxes showed that the model represents the dynamics of the nocturnal boundary layer (NBL) at Cabauw very well for a broad range of mechanical forcing conditions. No obvious difference in model performance was found between near-neutral and strongly-stratified conditions. Furthermore, observed NBL regime transitions are represented in a natural way. The reference model version performs much better than a model version that applies excessive vertical mixing as is done in several (global) operational models. Model sensitivity runs showed that for weak-wind conditions the inversion strength depends much more on details of the land-atmosphere coupling than on the turbulent mixing. The presented results indicate that in principle the physical parametrizations of large-scale atmospheric models are sufficiently equipped for modelling stably-stratified conditions for a wide range of forcing conditions.

  5. From Near-Neutral to Strongly Stratified: Adequately Modelling the Clear-Sky Nocturnal Boundary Layer at Cabauw

    Science.gov (United States)

    Baas, P.; van de Wiel, B. J. H.; van der Linden, S. J. A.; Bosveld, F. C.

    2018-02-01

    The performance of an atmospheric single-column model (SCM) is studied systematically for stably-stratified conditions. To this end, 11 years (2005-2015) of daily SCM simulations were compared to observations from the Cabauw observatory, The Netherlands. Each individual clear-sky night was classified in terms of the ambient geostrophic wind speed with a 1 m s^{-1} bin-width. Nights with overcast conditions were filtered out by selecting only those nights with an average net radiation of less than - 30 W m^{-2}. A similar procedure was applied to the observational dataset. A comparison of observed and modelled ensemble-averaged profiles of wind speed and potential temperature and time series of turbulent fluxes showed that the model represents the dynamics of the nocturnal boundary layer (NBL) at Cabauw very well for a broad range of mechanical forcing conditions. No obvious difference in model performance was found between near-neutral and strongly-stratified conditions. Furthermore, observed NBL regime transitions are represented in a natural way. The reference model version performs much better than a model version that applies excessive vertical mixing as is done in several (global) operational models. Model sensitivity runs showed that for weak-wind conditions the inversion strength depends much more on details of the land-atmosphere coupling than on the turbulent mixing. The presented results indicate that in principle the physical parametrizations of large-scale atmospheric models are sufficiently equipped for modelling stably-stratified conditions for a wide range of forcing conditions.

  6. 77 FR 58194 - Self-Regulatory Organizations; The Options Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2012-09-19

    ....S. Generally Accepted Accounting Principles. Canadian clearing members that use Form 1 report the... Organizations; The Options Clearing Corporation; Notice of Filing of Proposed Rule Change Relating to Financial... technical ``housekeeping'' changes to OCC's By-Laws and Rules relating to financial reporting by Canadian...

  7. 77 FR 27255 - Self-Regulatory Organizations; ICE Clear Credit LLC; Order Approving Proposed Rule Change To...

    Science.gov (United States)

    2012-05-09

    ... Organizations; ICE Clear Credit LLC; Order Approving Proposed Rule Change To Reduce the Current Level of Risk Mutualization Among Clearing Participants and To Modify the Initial Margin Risk Model So That It Is Easier for... modifications to its risk model for clearing credit default swaps (``CDS'') contracts. For the first...

  8. 77 FR 73106 - Self-Regulatory Organizations; ICE Clear Credit LLC; Notice of Withdrawal of Proposed Rule Change...

    Science.gov (United States)

    2012-12-07

    ... default swaps and European Corporate Single-Name credit default swaps. Notice of the proposed rule change... Organizations; ICE Clear Credit LLC; Notice of Withdrawal of Proposed Rule Change To Add Rules Related to the Clearing of iTraxx Europe Index CDS and European Corporate Single-Name CDS December 3, 2012. On September...

  9. Derotation of the cosmic microwave background polarization: Full-sky formalism

    International Nuclear Information System (INIS)

    Gluscevic, Vera; Kamionkowski, Marc; Cooray, Asantha

    2009-01-01

    Mechanisms have been proposed that might rotate the linear polarization of the cosmic microwave background (CMB) as it propagates from the surface of last scatter. In the simplest scenario, the rotation will be uniform across the sky, but the rotation angle may also vary across the sky. We develop in detail the complete set of full-sky quadratic estimators for the rotation of the CMB polarization that can be constructed from the CMB temperature and polarization. We derive the variance with which these estimators can be measured and show that these variances reduce to the simpler flat-sky expressions in the appropriate limit. We evaluate the variances numerically. While the flat-sky formalism may be suitable if the rotation angle arises as a realization of a random field, the full-sky formalism will be required to search for rotations that vary slowly across the sky as well as for models in which the angular power spectrum for the rotation angle peaks at large angles.

  10. Using a field radiometer to estimate instantaneous sky clearness Radiômetro de campo para cálculo da clareza instantânea do céu

    Directory of Open Access Journals (Sweden)

    Eduardo G. Souza

    2006-06-01

    Full Text Available Reflectance measurements of crop plants and canopies show promise for guiding within-season, variable-rate nitrogen (N application. Most research results have been obtained around solar noon with clear skies. However, for practical application, the system must work under cloudy skies or away from solar noon. The objective of this work was to assess the effect of cloud conditions on reflectance measurements of a corn canopy. The approach was to estimate an instantaneous sky clearness index (ICI which could be used to correct field radiometer data for variations in cloud cover, such that the same reflectance reading would be obtained (and the same N recommendation made for the same plants regardless of cloud conditions. Readings were taken from morning until night over 11 days with a range of sky conditions (sunny, overcast, partly cloudy. Data from clear days were used to estimate the theoretical expected spectral global radiation incident on a horizontal surface. The ICI was calculated as the ratio between the actual spectral global radiation and the corresponding theoretical global radiation. Analysis of the ICI for each band showed that the influence of cloudiness was different for each band. Thus, the cloud effect could not be compensated by the use of a band ratio or vegetation index.Medidas da reflectância das folhas das plantas mostram-se promissoras para a aplicação de nitrogênio a taxa variável; entretanto, a maioria dos resultados de pesquisa foi obtida ao redor do meio-dia solar e com céu aberto, porém para aplicações práticas um sistema tem que trabalhar debaixo de céu nublado e fora do meio-dia solar. O objetivo deste trabalho foi avaliar o efeito de condições de nuvem em medidas de reflectância de milho. A abordagem foi calcular um índice instantâneo de clareza do céu (ICI que pode ser usado para corrigir dados de radiômetros de campo para variações em cobertura de nuvem, tal que essas reflectâncias seriam

  11. Visual astronomy under dark skies a new approach to observing deep space

    CERN Document Server

    Cooke, Antony

    2005-01-01

    Modern astronomical telescopes, along with other advances in technology, have brought the deep sky - star clusters, nebulae and the galaxies - within reach of amateur astronomers. And it isn't even necessary to image many of these deep-sky objects in order to see them; they are within reach of visual observers using modern techniques and enhancement technology. The first requirement is truly dark skies; if you are observing from a light-polluted environment you need Tony Cooke's book, Visual Astronomy in the Suburbs. Given a site with clear, dark night skies everything else follows… this book will provide the reader with everything he needs to know about what to observe, and using some of today's state-of-the-art technique and commercial equipment, how to get superb views of faint and distant astronomical objects.

  12. The angular distributions of ultraviolet spectral irradiance at different solar elevation angles under clear sky conditions

    Science.gov (United States)

    Liu, Yan; Hu, LiWen; Wang, Fang; Gao, YanYan; Zheng, Yang; Wang, Yu; Liu, Yang

    2016-01-01

    To investigate the angular distributions of UVA, UVB, and effective UV for erythema and vitamin D (vitD) synthesis, the UV spectral irradiances were measured at ten inclined angles (from 0° to 90°) and seven azimuths (from 0° to 180°) at solar elevation angle (SEA) that ranged from 18.8° to 80° in Shanghai (31.22° N, 121.55° E) under clear sky and the albedo of ground was 0.1. The results demonstrated that in the mean azimuths and with the back to the sun, the UVA, UVB, and erythemally and vitD-weighted irradiances increased with the inclined angles and an increase in SEA. When facing toward the sun at 0°-60° inclined angles, the UVA first increased and then decreased with an increase in SEA; at other inclined angles, the UVA increased with SEA. At 0°-40° inclined angles, the UVB and erythemally and vitD-weighted irradiances first increased and then decreased with an increase in SEA, and their maximums were achieved at SEA 68.7°; at other inclined angles, the above three irradiances increased with an increase in SEA. The maximum UVA, UVB, and erythemally and vitD-weighted irradiances were achieved at an 80° inclined angle at SEA 80° (the highest in our measurements); the cumulative exposure of the half day achieved the maximum at a 60° inclined angle, but not on the horizontal. This study provides support for the assessment of human skin sun exposure.

  13. Reconstruction of Sky Illumination Domes from Ground-Based Panoramas

    Science.gov (United States)

    Coubard, F.; Lelégard, L.; Brédif, M.; Paparoditis, N.; Briottet, X.

    2012-07-01

    The knowledge of the sky illumination is important for radiometric corrections and for computer graphics applications such as relighting or augmented reality. We propose an approach to compute environment maps, representing the sky radiance, from a set of ground-based images acquired by a panoramic acquisition system, for instance a mobile-mapping system. These images can be affected by important radiometric artifacts, such as bloom or overexposure. A Perez radiance model is estimated with the blue sky pixels of the images, and used to compute additive corrections in order to reduce these radiometric artifacts. The sky pixels are then aggregated in an environment map, which still suffers from discontinuities on stitching edges. The influence of the quality of estimated sky radiance on the simulated light signal is measured quantitatively on a simple synthetic urban scene; in our case, the maximal error for the total sensor radiance is about 10%.

  14. RECONSTRUCTION OF SKY ILLUMINATION DOMES FROM GROUND-BASED PANORAMAS

    Directory of Open Access Journals (Sweden)

    F. Coubard

    2012-07-01

    Full Text Available The knowledge of the sky illumination is important for radiometric corrections and for computer graphics applications such as relighting or augmented reality. We propose an approach to compute environment maps, representing the sky radiance, from a set of ground-based images acquired by a panoramic acquisition system, for instance a mobile-mapping system. These images can be affected by important radiometric artifacts, such as bloom or overexposure. A Perez radiance model is estimated with the blue sky pixels of the images, and used to compute additive corrections in order to reduce these radiometric artifacts. The sky pixels are then aggregated in an environment map, which still suffers from discontinuities on stitching edges. The influence of the quality of estimated sky radiance on the simulated light signal is measured quantitatively on a simple synthetic urban scene; in our case, the maximal error for the total sensor radiance is about 10%.

  15. 78 FR 37640 - Self-Regulatory Organizations; The Options Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2013-06-21

    ... Clearing Members The proposed rule change relates to OCC governance issues. OCC believes that it would... discussed any comments it received on the proposed rule change. The text of these statements may be examined... corporate governance matter dividing the powers and duties of the Chairman into two positions was desirable...

  16. 75 FR 51867 - Self-Regulatory Organizations; National Securities Clearing Corporation; Order Approving Proposed...

    Science.gov (United States)

    2010-08-23

    ... VII (CNS Accounting Operation) NSCC will modify Procedure VII to provide for the tracking of customer.... I. Introduction On June 4, 2010, National Securities Clearing Corporation (``NSCC'') filed with the... 19(b)(1) of the Securities Exchange Act of 1934 (``Act'').\\1\\ The proposed rule change was published...

  17. A Satellite-Derived Climate-Quality Data Record of the Clear-Sky Surface Temperature of the Greenland Ice Sheet

    Science.gov (United States)

    Hall, Dorothy K.; Comiso, Josefino C.; DiGirolamo, Nikolo E.; Shuman, Christopher A.; Key, Jeffrey R.; Koenig, Lora S.

    2012-01-01

    We have developed a climate-quality data record of the clear-sky surface temperature of the Greenland Ice Sheet using the Moderate-Resolution Imaging Spectroradiometer (MODIS) ice-surface temperature (1ST) algorithm. A climate-data record (CDR) is a time series of measurements of sufficient length, consistency, and continuity to determine climate variability and change. We present daily and monthly MODIS ISTs of the Greenland Ice Sheet beginning on 1 March 2000 and continuing through 31 December 2010 at 6.25-km spatial resolution on a polar stereographic grid. This record will be elevated in status to a CDR when at least nine more years of data become available either from MODIS Terra or Aqua, or from the Visible Infrared Imager Radiometer Suite (VIIRS) to be launched in October 2011. Our ultimate goal is to develop a CDR that starts in 1981 with the Advanced Very High Resolution (AVHRR) Polar Pathfinder (APP) dataset and continues with MODIS data from 2000 to the present, and into the VIIRS era. Differences in the APP and MODIS cloud masks have so far precluded the current 1ST records from spanning both the APP and MODIS time series in a seamless manner though this will be revisited when the APP dataset has been reprocessed. The complete MODIS 1ST daily and monthly data record is available online.

  18. Measuring the influence of aerosols and albedo on sky polarization.

    Science.gov (United States)

    Kreuter, A; Emde, C; Blumthaler, M

    2010-11-01

    All-sky distributions of the polarized radiance are measured using an automated fish-eye camera system with a rotating polarizer. For a large range of aerosol and surface albedo situations, the influence on the degree of polarization and sky radiance is investigated. The range of aerosol optical depth and albedo is 0.05-0.5 and 0.1-0.75, respectively. For this range of parameters, a reduction of the degree of polarization from about 0.7 to 0.4 was observed. The analysis is done for 90° scattering angle in the principal plane under clear sky conditions for a broadband channel of 450 ± 25 nm and solar zenith angles between 55° and 60°. Radiative transfer calculations considering three different aerosol mixtures are performed and and agree with the measurements within the statistical error.

  19. A Climate-Data Record (CDR) of the "Clear Sky" Surface Temperature of the Greenland Ice Sheet

    Science.gov (United States)

    Hall, Dorothy K.; Comiso, J. C.; DiGirolamo, N. E.; Shuman, C. A.

    2011-01-01

    To quantify the ice-surface temperature (IST) we are developing a climate-data record (CDR) of monthly IST of the Greenland ice sheet, from 1982 to the present using Advanced Very High Resolution Radiometer (AVHRR) and Moderate-Resolution Imaging Spectroradiometer (MODIS) data at 5-km resolution. "Clear-sky" surface temperature increases have been measured from the early 1980s to the early 2000s in the Arctic using AVHRR data, showing increases ranging from 0.57-0.02 (Wang and Key, 2005) to 0.72 0.10 deg C per decade (Comiso, 2006). Arctic warming has implications for ice-sheet mass balance because much of the periphery of the ice sheet is near 0 deg C in the melt season and is thus vulnerable to more extensive melting (Hanna et al., 2008). The algorithm used for this work has a long history of measuring IST in the Arctic with AVHRR (Key and Haefliger, 1992). The data are currently available from 1981 to 2004 in the AVHRR Polar Pathfinder (APP) dataset (Fowler et al., 2000). J. Key1NOAA modified the AVHRR algorithm for use with MODIS (Hall et al., 2004). The MODIS algorithm is now being processed over Greenland. Issues being addressed in the production of the CDR are: time-series bias caused by cloud cover, and cross-calibration between AVHRR and MODIS instruments. Because of uncertainties, time series of satellite ISTs do not necessarily correspond with actual surface temperatures. The CDR will be validated by comparing results with in-situ (see Koenig and Hall, in press) and automatic-weather station data (e.g., Shuman et al., 2001).

  20. Cooling load reduction by means of night sky radiation

    International Nuclear Information System (INIS)

    Kamaruddin Abdullah; Armansyah, H.T.; Dyah, W.; Gunadnya, I.B.P.

    2006-01-01

    Nocturnal cooling can work under clear sky condition of the humid tropical climate. Such effect had been observed in a cool storage facilities for potatoes and for temporary storage of fresh vegetables installed in highland area of Candi kuning village of Bali. Test results have shown that the rate of heat dissipation to the sky could reduce storage temperature to 15 o C had been achieved when the nocturnal cooling unit was combined with modified cooling tower and 1 kW cooling effect of an auxiliary cooling unit. Under such condition the facility could maintain better quality of stored vegetables, such as broccoli, shallot, and celery as compared to those stored in room without cooling facility. The estimated average cooling rate due to night sky radiation was 47.6 W/m 2 , on September 28, 1999 and 47.2 W/m 2 with the lowest water temperature of 14 o C under ambient temperature of 16 o C

  1. Sky camera imagery processing based on a sky classification using radiometric data

    International Nuclear Information System (INIS)

    Alonso, J.; Batlles, F.J.; López, G.; Ternero, A.

    2014-01-01

    As part of the development and expansion of CSP (concentrated solar power) technology, one of the most important operational requirements is to have complete control of all factors which may affect the quantity and quality of the solar power produced. New developments and tools in this field are focused on weather forecasting improving both operational security and electricity production. Such is the case with sky cameras, devices which are currently in use in some CSP plants and whose use is expanding in the new technology sector. Their application is mainly focused on cloud detection, estimating their movement as well as their influence on solar radiation attenuation indeed, the presence of clouds is the greatest factor involved in solar radiation attenuation. The aim of this work is the detection and analysis of clouds from images taken by a TSI-880 model sky. In order to obtain accurate image processing, three different models were created, based on a previous sky classification using radiometric data and representative sky conditions parameters. As a consequence, the sky can be classified as cloudless, partially-cloudy or overcast, delivering an average success rate of 92% in sky classification and cloud detection. - Highlights: • We developed a methodology for detection of clouds in total sky imagery (TSI-880). • A classification of sky is presented according to radiometric data and sky parameters. • The sky can be classified as cloudless, partially cloudy and overcast. • The images processing is based on the sky classification for the detection of clouds. • The average success of the developed model is around 92%

  2. 76 FR 78059 - Self-Regulatory Organizations; Options Clearing Corporation; Order Approving Proposed Rule Change...

    Science.gov (United States)

    2011-12-15

    ... SECURITIES AND EXCHANGE COMMISSION [Release No. 34-65927; File No. SR-OCC-2011-15] Self-Regulatory Organizations; Options Clearing Corporation; Order Approving Proposed Rule Change Relating to Management of..., future regulatory requirements for clearinghouses could impose liquidity requirements that would be...

  3. Dark Sky Protection and Education - Izera Dark Sky Park

    Science.gov (United States)

    Berlicki, Arkadiusz; Kolomanski, Sylwester; Mrozek, Tomasz; Zakowicz, Grzegorz

    2015-08-01

    Darkness of the night sky is a natural component of our environment and should be protected against negative effects of human activities. The night darkness is necessary for balanced life of plants, animals and people. Unfortunately, development of human civilization and technology has led to the substantial increase of the night-sky brightness and to situation where nights are no more dark in many areas of the World. This phenomenon is called "light pollution" and it can be rank among such problems as chemical pollution of air, water and soil. Besides the environment, the light pollution can also affect e.g. the scientific activities of astronomers - many observatories built in the past began to be located within the glow of city lights making the night observations difficult, or even impossible.In order to protect the natural darkness of nights many so-called "dark sky parks" were established, where the darkness is preserved, similar to typical nature reserves. The role of these parks is not only conservation but also education, supporting to make society aware of how serious the problem of the light pollution is.History of the dark sky areas in Europe began on November 4, 2009 in Jizerka - a small village situated in the Izera Mountains, when Izera Dark Sky Park (IDSP) was established - it was the first transboundary dark sky park in the World. The idea of establishing that dark sky park in the Izera Mountains originated from a need to give to the society in Poland and Czech Republic the knowledge about the light pollution. Izera Dark Sky Park is a part of the astro-tourism project "Astro Izery" that combines tourist attraction of Izera Valley and astronomical education under the wonderful starry Izera sky. Besides the IDSP, the project Astro Izery consists of the set of simple astronomical instruments (gnomon, sundial), natural educational trail "Solar System Model", and astronomical events for the public. In addition, twice a year we organize a 3-4 days

  4. Evaluation of sea-surface photosynthetically available radiation algorithms under various sky conditions and solar elevations.

    Science.gov (United States)

    Somayajula, Srikanth Ayyala; Devred, Emmanuel; Bélanger, Simon; Antoine, David; Vellucci, V; Babin, Marcel

    2018-04-20

    In this study, we report on the performance of satellite-based photosynthetically available radiation (PAR) algorithms used in published oceanic primary production models. The performance of these algorithms was evaluated using buoy observations under clear and cloudy skies, and for the particular case of low sun angles typically encountered at high latitudes or at moderate latitudes in winter. The PAR models consisted of (i) the standard one from the NASA-Ocean Biology Processing Group (OBPG), (ii) the Gregg and Carder (GC) semi-analytical clear-sky model, and (iii) look-up-tables based on the Santa Barbara DISORT atmospheric radiative transfer (SBDART) model. Various combinations of atmospheric inputs, empirical cloud corrections, and semi-analytical irradiance models yielded a total of 13 (11 + 2 developed in this study) different PAR products, which were compared with in situ measurements collected at high frequency (15 min) at a buoy site in the Mediterranean Sea (the "BOUée pour l'acquiSition d'une Série Optique à Long termE," or, "BOUSSOLE" site). An objective ranking method applied to the algorithm results indicated that seven PAR products out of 13 were well in agreement with the in situ measurements. Specifically, the OBPG method showed the best overall performance with a root mean square difference (RMSD) (bias) of 19.7% (6.6%) and 10% (6.3%) followed by the look-up-table method with a RMSD (bias) of 25.5% (6.8%) and 9.6% (2.6%) at daily and monthly scales, respectively. Among the four methods based on clear-sky PAR empirically corrected for cloud cover, the Dobson and Smith method consistently underestimated daily PAR while the Budyko formulation overestimated daily PAR. Empirically cloud-corrected methods using cloud fraction (CF) performed better under quasi-clear skies (CF0.7), however, all methods showed larger RMSD differences (biases) ranging between 32% and 80.6% (-54.5%-8.7%). Finally, three methods tested for low sun elevations revealed

  5. Research on Extraction of Ship Target in Complex Sea-sky Background

    International Nuclear Information System (INIS)

    Kang, W J; Ding, X M; Cui, J W; Ao, L

    2006-01-01

    Research on the extraction of ship target in complex sea-sky background has important value to improve the capability of imaging-typed sea navigation and nautical traffic control systems. According to the imaging property of complex sea-sky background, a reliable ship target extraction method is proposed in this paper. The general guide line is that getting the sea-sky division line as a priori knowledge and then the target potential area is determined through discontinuous region of the sea-sky division line. Firstly, a local selective window filter is adopted to filter the image; secondly, eight directions Sobel operator edge detection method and gradient Hough transform are combined to extract sea-sky division line in the image; then a multi-histogram matching technique is adopted to remove the sea and sky background and thus ship target is extracted from complex background. The experiments show that our method has the merits of robustness to noise, small computational complexity and stability

  6. Maritime Aerosol optical properties measured by ship-borne sky radiometer

    Science.gov (United States)

    Aoki, K.

    2017-12-01

    Maritime aerosols play an important role in the earth climate change. We started the measurements of aerosol optical properties since 1994 by using ship-borne sky radiometer (POM-01 MK-II and III; Prede Co. Ltd., Japan) over the ocean. We report the results of an aerosol optical properties over the ocean by using Research Vessel of the ship-borne sky radiometers. Aerosol optical properties observation were made in MR10-02 to MR16-09 onboard the R/V Mirai, JAMSTEC. The sky radiometer measure the direct and diffuse solar radiance with seven interference filters (0.315, 0.4, 0.5, 0.675, 0.87, 0.94, and 1.02 µm). Observation interval was made every five minutes by once, only in daytime under the clear sky conditions. GPS provides the position with longitude and latitude and heading direction of the vessel, and azimuth and elevation angle of the sun. The aerosol optical properties were computed using the SKYRAD.pack version 4.2. The obtained Aerosol optical properties (Aerosol optical thickness, Ångström exponent, Single scattering albedo, and etc.) and size distribution volume clearly showed spatial and temporal variability over the ocean. Aerosol optical thickness found over the near the coast (Asia and Tropical area) was high and variable. The size distribution volume have peaks at small particles at Asian coast and large particles at Tropical coast area. We provide the information, in this presentation, on the aerosol optical properties measurements with temporal and spatial variability in the Maritime Aerosol. This project is validation satellite of GCOM-C/SGLI, JAXA and other. The GCOM-C satellite scheduled to be launched in 2017 JFY.

  7. 78 FR 28680 - Self-Regulatory Organizations; ICE Clear Credit LLC; Notice of Withdrawal of Proposed Rule Change...

    Science.gov (United States)

    2013-05-15

    ... SECURITIES AND EXCHANGE COMMISSION [Release No. 34-69545; File No. SR-ICC-2013-03] Self-Regulatory Organizations; ICE Clear Credit LLC; Notice of Withdrawal of Proposed Rule Change Relating to Recovery and Resolution Arrangements May 9, 2013. On March 7, 2013, ICE Clear Credit LLC (``ICC'') filed with the...

  8. Dark Sky Education | CTIO

    Science.gov (United States)

    Calendar Activities NOAO-S EPO Programs CADIAS Astro Chile Hugo E. Schwarz Telescope Dark Sky Education ‹› You are here CTIO Home » Outreach » NOAO-S EPO Programs » Dark Sky Education Dark Sky Education Dark Sky Education (in progress) Is an EPO Program. It runs Globe at Night, an annual program to

  9. Traces on sky. Unexpected results of regular observations

    Science.gov (United States)

    Churyumov, K. I.; Steklov, A. F.; Vidmachenko, A. P.; Dashkiev, N. G.; Steklov, E. A.

    2016-08-01

    If the fireball's track has noticeable angular size, it can be seen even in the daytime. After the flight, bolide remains a noticeable trace of a dust, dark against the light sky. If such a dust trail illuminated by the rays of the Sun, which had just hid behind the horizon (or even in the moonlight), it is visible as bright lanes in the night sky or in twilight. That's why we call it the twilight bolides. Usually, astronomical observations using of meteor patrols, carried out at night after the evening astronomical twilight. But from March 2013 to October 2015, the authors have obtained several thousands of different tracks in the sky over Kiev. Therefore, we have identified a special class of twilight observations of fireballs. We register the traces of invading to atmosphere of meteoroids of natural and artificial origin. At the same time, observe the traces of fireballs at the day-time are also possible. But they are less effective than in the twilight. Night observations of bright meteoric tracks can usually observe some seconds. While traces of the twilight bolides we observed from some minutes up to two hours, before they be scattered by atmospheric currents. It opens the great prospects for low-cost direct experiments probing of these tracks by using, for example, the astronomical aviation. We propose the twilight tracks are classified into the following types: AMT - aero-meteorological tracks, AST - aero-space, ATT - aero-technical, and NST - not yet classified tracks of unknown nature. During the short period of our observations (from March 2013 to 2016), was fixed falling at least a dozen fragments of cometary nuclei, at least five of sufficiently large and dozens of smaller fragments of meteoroids. The results of our observations also showed that during the morning and evening twilight over Kiev clearly visible the plume of aerosols of technical nature from the plants, factories and other production facilities.

  10. AMSR2 all-sky radiance assimilation and its impact on the analysis and forecast of Hurricane Sandy with a limited-area data assimilation system

    Directory of Open Access Journals (Sweden)

    Chun Yang

    2016-06-01

    Full Text Available A method to assimilate all-sky radiances from the Advanced Microwave Scanning Radiometer 2 (AMSR2 was developed within the Weather Research and Forecasting (WRF model's data assimilation (WRFDA system. The four essential elements are: (1 extending the community radiative transform model's (CRTM interface to include hydrometeor profiles; (2 using total water Qt as the moisture control variable; (3 using a warm-rain physics scheme for partitioning the Qt increment into individual increments of water vapour, cloud liquid water and rain; and (4 adopting a symmetric observation error model for all-sky radiance assimilation.Compared to a benchmark experiment with no AMSR2 data, the impact of assimilating clear-sky or all-sky AMSR2 radiances on the analysis and forecast of Hurricane Sandy (2012 was assessed through analysis/forecast cycling experiments using WRF and WRFDA's three-dimensional variational (3DVAR data assimilation scheme. With more cloud/precipitation-affected data being assimilated around tropical cyclone (TC core areas in the all-sky AMSR2 assimilation experiment, better analyses were obtained in terms of the TC's central sea level pressure (CSLP, warm-core structure and cloud distribution. Substantial (>20 % error reduction in track and CSLP forecasts was achieved from both clear-sky and all-sky AMSR2 assimilation experiments, and this improvement was consistent from the analysis time to 72-h forecasts. Moreover, the all-sky assimilation experiment consistently yielded better track and CSLP forecasts than the clear-sky did for all forecast lead times, due to a better analysis in the TC core areas. Positive forecast impact from assimilating AMSR2 radiances is also seen when verified against the European Center for Medium-Range Weather Forecasts (ECMWF analysis and the Stage IV precipitation analysis, with an overall larger positive impact from the all-sky assimilation experiment.

  11. High Spectral Resolution Infrared and Raman Lidar Observations for the ARM Program: Clear and Cloudy Sky Applications

    Energy Technology Data Exchange (ETDEWEB)

    Revercomb, Henry; Tobin, David; Knuteson, Robert; Borg, Lori; Moy, Leslie

    2009-06-17

    This grant began with the development of the Atmospheric Emitted Radiance Interferometer (AERI) for ARM. The AERI has provided highly accurate and reliable observations of downwelling spectral radiance (Knuteson et al. 2004a, 2004b) for application to radiative transfer, remote sensing of boundary layer temperature and water vapor, and cloud characterization. One of the major contributions of the ARM program has been its success in improving radiation calculation capabilities for models and remote sensing that evolved from the multi-year, clear-sky spectral radiance comparisons between AERI radiances and line-by-line calculations (Turner et al. 2004). This effort also spurred us to play a central role in improving the accuracy of water vapor measurements, again helping ARM lead the way in the community (Turner et al. 2003a, Revercomb et al. 2003). In order to add high-altitude downlooking AERI-like observations over the ARM sites, we began the development of an airborne AERI instrument that has become known as the Scanning High-resolution Interferometer Sounder (Scanning-HIS). This instrument has become an integral part of the ARM Unmanned Aerospace Vehicle (ARM-UAV) program. It provides both a cross-track mapping view of the earth and an uplooking view from the 12-15 km altitude of the Scaled Composites Proteus aircraft when flown over the ARM sites for IOPs. It has successfully participated in the first two legs of the “grand tour” of the ARM sites (SGP and NSA), resulting in a very good comparison with AIRS observations in 2002 and in an especially interesting data set from the arctic during the Mixed-Phase Cloud Experiment (M-PACE) in 2004.

  12. Polarization optics of the Brewster's dark patch visible on water surfaces versus solar height and sky conditions: theory, computer modeling, photography, and painting.

    Science.gov (United States)

    Takács, Péter; Barta, András; Pye, David; Horváth, Gábor

    2017-10-20

    When the sun is near the horizon, a circular band with approximately vertically polarized skylight is formed at 90° from the sun, and this skylight is only weakly reflected from the region of the water surface around the Brewster's angle (53° from the nadir). Thus, at low solar heights under a clear sky, an extended dark patch is visible on the water surface when one looks toward the north or south quarter perpendicular to the solar vertical. In this work, we study the radiance distribution of this so-called Brewster's dark patch (BDP) in still water as functions of the solar height and sky conditions. We calculate the pattern of reflectivity R of a water surface for a clear sky and obtain from this idealized situation the shape of the BDP. From three full-sky polarimetric pictures taken about a clear, a partly cloudy, and an overcast sky, we determine the R pattern and compose from that synthetic color pictures showing how the radiance distribution of skylight reflected at the water surface and the BDPs would look under these sky conditions. We also present photographs taken without a linearly polarizing filter about the BDP. Finally, we show a 19th century painting on which a river is seen with a dark region of the water surface, which can be interpreted as an artistic illustration of the BDP.

  13. PePSS - A portable sky scanner for measuring extremely low night-sky brightness

    Science.gov (United States)

    Kocifaj, Miroslav; Kómar, Ladislav; Kundracik, František

    2018-05-01

    A new portable sky scanner designed for low-light-level detection at night is developed and employed in night sky brightness measurements in a rural region. The fast readout, adjustable sensitivity and linear response guaranteed in 5-6 orders of magnitude makes the device well suited for narrow-band photometry in both dark areas and bright urban and suburban environments. Quasi-monochromatic night-sky brightness data are advantageous in the accurate characterization of spectral power distribution of scattered and emitted light and, also allows for the possibility to retrieve light output patterns from whole-city light sources. The sky scanner can operate in both night and day regimes, taking advantage of the complementarity of both radiance data types. Due to its inherent very high sensitivity the photomultiplier tube could be used in night sky radiometry, while the spectrometer-equipped system component capable of detecting elevated intensities is used in daylight monitoring. Daylight is a source of information on atmospheric optical properties that in turn are necessary in processing night sky radiances. We believe that the sky scanner has the potential to revolutionize night-sky monitoring systems.

  14. Celestial polarization patterns sufficient for Viking navigation with the naked eye: detectability of Haidinger's brushes on the sky versus meteorological conditions

    Science.gov (United States)

    Horváth, Gábor; Takács, Péter; Kretzer, Balázs; Szilasi, Szilvia; Száz, Dénes; Farkas, Alexandra; Barta, András

    2017-02-01

    If a human looks at the clear blue sky from which light with high enough degree of polarization d originates, an 8-shaped bowtie-like figure, the yellow Haidinger's brush can be perceived, the long axis of which points towards the sun. A band of high d arcs across the sky at 90° from the sun. A person can pick two points on that band, observe the yellow brushes and triangulate the position of the sun based on the orientation of the two observed brushes. This method has been suggested to have been used on the open sea by Viking navigators to determine the position of the invisible sun occluded by cloud or fog. Furthermore, Haidinger's brushes can also be used to locate the sun when it is below the horizon or occluded by objects on the horizon. To determine the position of the sun using the celestial polarization pattern, the d of the portion of the sky used must be greater than the viewer's degree of polarization threshold d* for perception of Haidinger's brushes. We studied under which sky conditions the prerequisite d > d* is satisfied. Using full-sky imaging polarimetry, we measured the d-pattern of skylight in the blue (450 nm) spectral range for 1296 different meteorological conditions with different solar elevation angles θ and per cent cloud cover ρ. From the measured d-patterns of a given sky we determined the proportion P of the sky for which d > d*. We obtained that P is the largest at low solar elevations θ ≈ 0° and under totally or nearly clear skies with cloud coverage ρ = 0%, when the sun's position is already easily determined. If the sun is below the horizon (-5° ≤ θ Viking navigation based on Haidinger's brushes is most useful after sunset and prior to sunrise, when the sun is not visible and large sky regions are bright, clear and polarized enough for perception of Haidinger's brushes.

  15. Retrieval of Garstang's emission function from all-sky camera images

    Science.gov (United States)

    Kocifaj, Miroslav; Solano Lamphar, Héctor Antonio; Kundracik, František

    2015-10-01

    The emission function from ground-based light sources predetermines the skyglow features to a large extent, while most mathematical models that are used to predict the night sky brightness require the information on this function. The radiant intensity distribution on a clear sky is experimentally determined as a function of zenith angle using the theoretical approach published only recently in MNRAS, 439, 3405-3413. We have made the experiments in two localities in Slovakia and Mexico by means of two digital single lens reflex professional cameras operating with different lenses that limit the system's field-of-view to either 180º or 167º. The purpose of using two cameras was to identify variances between two different apertures. Images are taken at different distances from an artificial light source (a city) with intention to determine the ratio of zenith radiance relative to horizontal irradiance. Subsequently, the information on the fraction of the light radiated directly into the upward hemisphere (F) is extracted. The results show that inexpensive devices can properly identify the upward emissions with adequate reliability as long as the clear sky radiance distribution is dominated by a largest ground-based light source. Highly unstable turbidity conditions can also make the parameter F difficult to find or even impossible to retrieve. The measurements at low elevation angles should be avoided due to a potentially parasitic effect of direct light emissions from luminaires surrounding the measuring site.

  16. 78 FR 69167 - Self-Regulatory Organizations; ICE Clear Credit LLC; Order Approving Proposed Rule Change To...

    Science.gov (United States)

    2013-11-18

    ..., the Bolivian Republic of Venezuela, the Argentine Republic, the Republic of Turkey and the Russian... transactions, and ICC's proposal, in combination with its existing rules, policies, and procedures for clearing...

  17. [The backgroud sky subtraction around [OIII] line in LAMOST QSO spectra].

    Science.gov (United States)

    Shi, Zhi-Xin; Comte, Georges; Luo, A-Li; Tu, Liang-Ping; Zhao, Yong-Heng; Wu, Fu-Chao

    2014-11-01

    At present, most sky-subtraction methods focus on the full spectrum, not the particular location, especially for the backgroud sky around [OIII] line which is very important to low redshift quasars. A new method to precisely subtract sky lines in local region is proposed in the present paper, which sloves the problem that the width of Hβ-[OIII] line is effected by the backgroud sky subtraction. The exprimental results show that, for different redshift quasars, the spectral quality has been significantly improved using our method relative to the original batch program by LAMOST. It provides a complementary solution for the small part of LAMOST spectra which are not well handled by LAMOST 2D pipeline. Meanwhile, This method has been used in searching for candidates of double-peaked Active Galactic Nuclei.

  18. 77 FR 51599 - Self-Regulatory Organizations; ICE Clear Credit LLC; Notice of Filing of Proposed Rule Change To...

    Science.gov (United States)

    2012-08-24

    ... Proposed Rule Change As with the Standard North American Corporate Single Names currently cleared, ICC... the following twenty additional investment grade Standard North American Corporate Single Name CDS... Single Names do not require any changes to the body of the ICC Rules. ICC will clear the Additional...

  19. Three-dimensional cloud characterization from paired whole-sky imaging cameras

    International Nuclear Information System (INIS)

    Allmen, M.; Kegelmeyer, W.P. Jr.

    1994-01-01

    Three-dimensional (3-D) cloud characterization permits the derivation of important cloud geometry properties such as fractional cloudiness, mean cloud and clear length, aspect ratio, and the morphology of cloud cover. These properties are needed as input to the hierarchical diagnosis (HD) and instantaneous radiative transfer (IRF) models, to validate sub-models for cloud occurrence and formation, and to Central Site radiative flux calculations. A full 3-D characterization will eventually require the integration of disparate Cloud and Radiation Testbed (CART) data sources: whole-sky imagers (WSIs), radar, satellites, ceilometers, volume-imaging lidar, and other sensors. In this paper, we demonstrate how an initial 3-D cloud property, cloud base height, can be determined from fusing paired times series of images from two whole-sky imagers

  20. The Next Generation Sky Survey and the Quest for Cooler Brown Dwarfs

    OpenAIRE

    Kirkpatrick, J. Davy

    2002-01-01

    The Next Generation Sky Survey (NGSS) is a proposed NASA MIDEX mission to map the entire sky in four infrared bandpasses - 3.5, 4.7, 12, and 23 um. The seven-month mission will use a 50-cm telescope and four-channel imager to survey the sky from a circular orbit above the Earth. Expected sensitivities will be half a million times that of COBE/DIRBE at 3.5 and 4.7 um and a thousand times that of IRAS at 12 and 23 um. NGSS will be particularly sensitive to brown dwarfs cooler than those present...

  1. 78 FR 33456 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Notice of Filing Proposed Rule...

    Science.gov (United States)

    2013-06-04

    ... certain locked- in trade sources in the future based on volumes and processing costs. \\9\\ Designated...-Regulatory Organizations; Fixed Income Clearing Corporation; Notice of Filing Proposed Rule Change to Include trueEX LLC as a Designated Locked-In Trade Source Pursuant to the Rulebook of the Government Securities...

  2. Variable X-ray sky with Lobster Eye Telescopes

    International Nuclear Information System (INIS)

    Hudec, R.; Pina, L.; Inneman, A.; Sveda, L.

    2004-01-01

    The variable X-ray sky requires wide-field monitoring with high sensitivity. We refer on novel X-ray telescopes with high sensitivity as well as large field of view. The results are very promising, allowing the proposals for space projects with very wide-field Lobster-eye X-ray optics to be considered. The novel telescopes will monitor the sky with unprecedented sensitivity and angular resolution of order of 1 arcmin. They are expected to contribute essentially to study and to understand various astrophysical objects such as AGN, SNe, GRBs, X-ray flashes, galactic binary sources, stars, CVs, X-ray novae, various transient sources, etc

  3. 77 FR 17536 - Self-Regulatory Organizations; ICE Clear Credit LLC; Notice of Filing of Proposed Rule Change to...

    Science.gov (United States)

    2012-03-26

    ... Organizations; ICE Clear Credit LLC; Notice of Filing of Proposed Rule Change to Its Risk Model To Reduce the... Model so That It Is Easier for Market Participants To Measure Their Risk March 20, 2012. Pursuant to... is hereby given that on March 8, 2012, ICE Clear Credit LLC (``ICC'') filed with the Securities and...

  4. Sky coverage modeling for the whole sky for laser guide star multiconjugate adaptive optics.

    Science.gov (United States)

    Wang, Lianqi; Andersen, David; Ellerbroek, Brent

    2012-06-01

    The scientific productivity of laser guide star adaptive optics systems strongly depends on the sky coverage, which describes the probability of finding natural guide stars for the tip/tilt wavefront sensor(s) to achieve a certain performance. Knowledge of the sky coverage is also important for astronomers planning their observations. In this paper, we present an efficient method to compute the sky coverage for the laser guide star multiconjugate adaptive optics system, the Narrow Field Infrared Adaptive Optics System (NFIRAOS), being designed for the Thirty Meter Telescope project. We show that NFIRAOS can achieve more than 70% sky coverage over most of the accessible sky with the requirement of 191 nm total rms wavefront.

  5. Estimation of clearness index using neural network with meteorological forecast; Kisho yoho wo nyuryoku toshita neural network ni yoru seiten shisu no yosoku

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, S; Kenmoku, Y; Sakakibara, T [Toyohashi University of Technology, Aichi (Japan); Nakagawa, S [Maizuru National College of Technology, Kyoto (Japan); Kawamoto, T [Shizuoka University, Shizuoka (Japan)

    1997-11-25

    Discussions were given on estimation of clearness index in order to operate stably a solar energy utilizing system. All-sky insolation amount varies not only by change in the climate, but also seasonal change in the sun`s altitude. Therefore, a clearness index (ratio of all-sky insolation to out-of-atmosphere insolation) was used. The larger the value, the higher the solar ray permeability. The all-sky insolation amount is a measured value, while the out-of-atmosphere insolation amount is a calculated value. Although the clearness index may be roughly estimated by weather forecast, the clearness index varies largely even on the same weather forecast, especially for cloudy days, if a weather forecast actually having error is used. Therefore, discussions were given on estimation of the clearness index by using a neural network which uses meteorological information such as air temperatures and precipitation probabilities as inputs. Using multiple number of meteorological forecast information simultaneously has reduced the average square error to 49% of that using only the weather forecast. The estimation accuracy depends on the accuracy of meteorological forecast, but using multiple number of forecast information can improve the accuracy. 6 refs., 7 figs., 1 tab.

  6. Super-sample covariance approximations and partial sky coverage

    Science.gov (United States)

    Lacasa, Fabien; Lima, Marcos; Aguena, Michel

    2018-04-01

    Super-sample covariance (SSC) is the dominant source of statistical error on large scale structure (LSS) observables for both current and future galaxy surveys. In this work, we concentrate on the SSC of cluster counts, also known as sample variance, which is particularly useful for the self-calibration of the cluster observable-mass relation; our approach can similarly be applied to other observables, such as galaxy clustering and lensing shear. We first examined the accuracy of two analytical approximations proposed in the literature for the flat sky limit, finding that they are accurate at the 15% and 30-35% level, respectively, for covariances of counts in the same redshift bin. We then developed a harmonic expansion formalism that allows for the prediction of SSC in an arbitrary survey mask geometry, such as large sky areas of current and future surveys. We show analytically and numerically that this formalism recovers the full sky and flat sky limits present in the literature. We then present an efficient numerical implementation of the formalism, which allows fast and easy runs of covariance predictions when the survey mask is modified. We applied our method to a mask that is broadly similar to the Dark Energy Survey footprint, finding a non-negligible negative cross-z covariance, i.e. redshift bins are anti-correlated. We also examined the case of data removal from holes due to, for example bright stars, quality cuts, or systematic removals, and find that this does not have noticeable effects on the structure of the SSC matrix, only rescaling its amplitude by the effective survey area. These advances enable analytical covariances of LSS observables to be computed for current and future galaxy surveys, which cover large areas of the sky where the flat sky approximation fails.

  7. Dark Skies are a Universal Resource. So are Quiet Skies!

    Science.gov (United States)

    Maddalena, Ronald J.; Heatherly, S.

    2008-05-01

    You've just purchased your first telescope. But where to set it up? Certainly not a WalMart parking lot. Too much light pollution! In the same way that man-made light obscures our night sky and blinds ground-based optical telescopes, man-made radio signals blind radio telescopes as well. NRAO developed the Quiet Skies project to increase awareness of radio frequency interference (RFI) and radio astronomy in general by engaging students in local studies of RFI. To do that we created a sensitive detector which measures RFI. We produced 20 of these, and assembled kits containing detectors and supplementary materials for loan to schools. Students conduct experiments to measure the properties of RFI in their area, and input their measurements into a web-based data base. The Quiet Skies project is a perfect complement to the IYA Dark Skies Awareness initiative. We hope to place 500 Quiet Skies detectors into the field through outreach to museums and schools around the world. Should we be successful, we will sustain this global initiative via a continuing loan program. One day we hope to have a publicly generated image of the Earth which shows RFI much as the Earth at Night image illustrates light pollution. The poster will present the components of the project in detail, including our plans for IYA, and various low-cost alternative strategies for introducing RFI and radio astronomy to the public. We will share the results of some of the experiments already being performed by high school students. Development of the Quiet Skies project was funded by a NASA IDEAS grant. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

  8. Longterm and spatial variability of Aerosol optical properties measured by sky radiometer in Japan sites

    Science.gov (United States)

    Aoki, K.

    2016-12-01

    Aerosols and cloud play an important role in the climate change. We started the long-term monitoring of aerosol and cloud optical properties since 1990's by using sky radiometer (POM-01, 02; Prede Co. Ltd., Japan). We provide the information, in this presentation, on the aerosol optical properties with respect to their temporal and spatial variability in Japan site (ex. Sapporo, Toyama, Kasuga and etc). The global distributions of aerosols have been derived from earth observation satellite and have been simulated in numerical models, which assume optical parameters. However, these distributions are difficult to derive because of variability in time and space. Therefore, Aerosol optical properties were investigated using the measurements from ground-based and ship-borne sky radiometer. The sky radiometer is an automatic instrument that takes observations only in daytime under the clear sky conditions. Observation of diffuse solar intensity interval was made every ten or five minutes by once. The aerosol optical properties were computed using the SKYRAD.pack version 4.2. The obtained Aerosol optical properties (Aerosol optical thickness, Ångström exponent, Single scattering albedo, and etc.) and size distribution volume clearly showed spatial and temporal variability in Japan area. In this study, we present the temporal and spatial variability of Aerosol optical properties at several Japan sites, applied to validation of satellite and numerical models. This project is validation satellite of GCOM-C, JAXA. The GCOM-C satellite scheduled to be launched in early 2017.

  9. Solar Resource Assessment with Sky Imagery and a Virtual Testbed for Sky Imager Solar Forecasting

    Science.gov (United States)

    Kurtz, Benjamin Bernard

    In recent years, ground-based sky imagers have emerged as a promising tool for forecasting solar energy on short time scales (0 to 30 minutes ahead). Following the development of sky imager hardware and algorithms at UC San Diego, we present three new or improved algorithms for sky imager forecasting and forecast evaluation. First, we present an algorithm for measuring irradiance with a sky imager. Sky imager forecasts are often used in conjunction with other instruments for measuring irradiance, so this has the potential to decrease instrumentation costs and logistical complexity. In particular, the forecast algorithm itself often relies on knowledge of the current irradiance which can now be provided directly from the sky images. Irradiance measurements are accurate to within about 10%. Second, we demonstrate a virtual sky imager testbed that can be used for validating and enhancing the forecast algorithm. The testbed uses high-quality (but slow) simulations to produce virtual clouds and sky images. Because virtual cloud locations are known, much more advanced validation procedures are possible with the virtual testbed than with measured data. In this way, we are able to determine that camera geometry and non-uniform evolution of the cloud field are the two largest sources of forecast error. Finally, with the assistance of the virtual sky imager testbed, we develop improvements to the cloud advection model used for forecasting. The new advection schemes are 10-20% better at short time horizons.

  10. Photometric Assessment of Night Sky Quality over Chaco Culture National Historical Park

    Science.gov (United States)

    Hung, Li-Wei; Duriscoe, Dan M.; White, Jeremy M.; Meadows, Bob; Anderson, Sharolyn J.

    2018-06-01

    The US National Park Service (NPS) characterizes night sky conditions over Chaco Culture National Historical Park using measurements in the park and satellite data. The park is located near the geographic center of the San Juan Basin of northwestern New Mexico and the adjacent Four Corners state. In the park, we capture a series of night sky images in V-band using our mobile camera system on nine nights from 2001 to 2016 at four sites. We perform absolute photometric calibration and determine the image placement to obtain multiple 45-million-pixel mosaic images of the entire night sky. We also model the regional night sky conditions in and around the park based on 2016 VIIRS satellite data. The average zenith brightness is 21.5 mag/arcsec2, and the whole sky is only ~16% brighter than the natural conditions. The faintest stars visible to naked eyes have magnitude of approximately 7.0, reaching the sensitivity limit of human eyes. The main impacts to Chaco’s night sky quality are the light domes from Albuquerque, Rio Rancho, Farmington, Bloomfield, Gallup, Santa Fe, Grants, and Crown Point. A few of these light domes exceed the natural brightness of the Milky Way. Additionally, glare sources from oil and gas development sites are visible along the north and east horizons. Overall, the night sky quality at Chaco Culture National Historical Park is very good. The park preserves to a large extent the natural illumination cycles, providing a refuge for crepuscular and nocturnal species. During clear and dark nights, visitors have an opportunity to see the Milky Way from nearly horizon to horizon, complete constellations, and faint astronomical objects and natural sources of light such as the Andromeda Galaxy, zodiacal light, and airglow.

  11. 1,001 Celestial Wonders to See Before You Die The Best Sky Objects for Star Gazers

    CERN Document Server

    Bakich, Michael E

    2010-01-01

    Many deep-sky objects that can appear quite wonderful in photographs can be hard to observe in the telescope. This book is your guide to the more interesting nebulae, star clusters, and galaxies, objects that will bring gasps when you see them through a telescope. Author Michael E. Bakich shows you how to spot constellations you’ve heard of but haven’t been able to find. He gives you lists of bright deep-sky objects to target on clear nights. And he guides your search for the famous named splendors you’ve heard of — and perhaps seen a picture of — and would like to see through your own telescope. Bakich, an observer since he was in third grade, knows the sky better than most. In his current position as senior editor and also photo editor for the highly regarded Astronomy magazine, he has the technical expertise and finely honed communication skills to help you easily locate the best sites in the sky. His more than 250 astroimages help you identify the detail in these sky wonders. Bakich organizes hi...

  12. A Method for Deriving All-Sky Evapotranspiration From the Synergistic Use of Remotely Sensed Images and Meteorological Data

    Science.gov (United States)

    Leng, Pei; Li, Zhao-Liang; Duan, Si-Bo; Tang, Ronglin; Gao, Mao-Fang

    2017-12-01

    Evapotranspiration (ET) is an important component of the water and energy cycle. The present study develops a practical approach for generating all-sky ET with the synergistic use of satellite images and meteorological data. In this approach, the ET over clear-sky pixels is estimated from a two-stage land surface temperature (LST)/fractional vegetation cover feature space method where the dry/wet edges are determined from theoretical calculations. For cloudy pixels, the Penman-Monteith equation is used to calculate the ET where no valid remotely sensed LST is available. An evaluation of the method with ET collected at ground-based large aperture scintillometer measurements at the Yucheng Comprehensive Experimental Station (YCES) in China is performed over a growth period from April to October 2010. The results show that the root-mean-square error (RMSE) and bias over clear-sky pixels are 57.3 W/m2 and 18.2 W/m2, respectively, whereas an RMSE of 69.3 W/m2 with a bias of 12.3 W/m2 can be found over cloudy pixels. Moreover, a reasonable overall RMSE of 65.3 W/m2 with a bias of 14.4 W/m2 at the YCES can be obtained under all-sky conditions, indicating a promising prospect for the derivation of all-sky ET using currently available satellite and meteorological data at a regional or global scale in future developments.

  13. Treasures of the Southern Sky

    CERN Document Server

    Gendler, Robert; Malin, David

    2011-01-01

    In these pages, the reader can follow the engaging saga of astronomical exploration in the southern hemisphere, in a modern merger of aesthetics, science, and a story of human endeavor. This book is truly a celebration of southern skies.  Jerry Bonnell, Editor - Astronomy Picture of the Day The southern sky became accessible to scientific scrutiny only a few centuries ago, after the first European explorers ventured south of the equator. Modern observing and imaging techniques have since revealed what seems like a new Universe, previously hidden below the horizon, a fresh astronomical bounty of beauty and knowledge uniquely different from the northern sky. The authors have crafted a book that brings this hidden Universe to all, regardless of location or latitude. Treasures of the Southern Sky celebrates the remarkable beauty and richness of the southern sky in words and with world-class imagery. In part, a photographic anthology of deep sky wonders south of the celestial equator, this book also celebrates th...

  14. The night sky companion a yearly guide to sky-watching 2008-2009

    CERN Document Server

    Plotner, Tammy

    2007-01-01

    The Night Sky Companion is a comprehensive guide to what can be explored in the heavens on a nightly basis. Designed to appeal to readers at all skill levels, it provides a digest for sky watchers interested in all types of astronomical information.

  15. Celestial orientation with the sun not in view: lizards use a time-compensated sky polarization compass.

    Science.gov (United States)

    Maoret, Francesco; Beltrami, Giulia; Bertolucci, Cristiano; Foà, Augusto

    2014-04-01

    The present investigation was aimed at testing whether the lizard sky polarization compass is time compensated. For this purpose, ruin lizards, Podarcis sicula, were both trained and tested for orientation inside a Morris water maze under clear skies with the sun not in view. During training, lizards showed a striking bimodal orientation along the training axis, demonstrating their capability of determining the symmetry plane of the sky polarization pattern and thus the use of polarization information in orientation. After reaching criteria, lizards were kept 7 days in a 6-h fast clock-shift treatment and then released with the sun not in view. Six-hour clock-shifted lizards showed a bimodal distribution of directional choices, which was oriented perpendicularly to the training axis, as it was expected on the basis of the clock-shift. The results show that the only celestial diurnal compass mechanism that does not need a direct vision of the sun disk (i.e., the sky polarization compass) is a time-compensated compass.

  16. A new theory and its application to remove the effect of surface-reflected light in above-surface radiance data from clear and turbid waters

    International Nuclear Information System (INIS)

    Dev, Pravin Jeba; Shanmugam, Palanisamy

    2014-01-01

    time series and discrete radiometric data in a wide range of oceanic, coastal and inland water bodies under different sky and sun glint conditions. - Highlights: • A new theory is proposed to remove the surface-reflected light in radiometric data. • It is applied to radiometric data from clear, turbid and highly eutrophic waters. • Comparison with field data shows its success in a wide range of waters. • The new method proves to be a viable alternative to existing methods. • New L w data will be essential for algorithm development and vicarious calibration

  17. Sky Subtraction with Fiber-Fed Spectrograph

    Science.gov (United States)

    Rodrigues, Myriam

    2017-09-01

    "Historically, fiber-fed spectrographs had been deemed inadequate for the observation of faint targets, mainly because of the difficulty to achieve high accuracy on the sky subtraction. The impossibility to sample the sky in the immediate vicinity of the target in fiber instruments has led to a commonly held view that a multi-object fibre spectrograph cannot achieve an accurate sky subtraction under 1% contrary to their slit counterpart. The next generation of multi-objects spectrograph at the VLT (MOONS) and the planed MOS for the E-ELT (MOSAIC) are fiber-fed instruments, and are aimed to observed targets fainter than the sky continuum level. In this talk, I will present the state-of-art on sky subtraction strategies and data reduction algorithm specifically developed for fiber-fed spectrographs. I will also present the main results of an observational campaign to better characterise the sky spatial and temporal variations ( in particular the continuum and faint sky lines)."

  18. Imaging and mapping the impact of clouds on skyglow with all-sky photometry.

    Science.gov (United States)

    Jechow, Andreas; Kolláth, Zoltán; Ribas, Salvador J; Spoelstra, Henk; Hölker, Franz; Kyba, Christopher C M

    2017-07-27

    Artificial skyglow is constantly growing on a global scale, with potential ecological consequences ranging up to affecting biodiversity. To understand these consequences, worldwide mapping of skyglow for all weather conditions is urgently required. In particular, the amplification of skyglow by clouds needs to be studied, as clouds can extend the reach of skyglow into remote areas not affected by light pollution on clear nights. Here we use commercial digital single lens reflex cameras with fisheye lenses for all-sky photometry. We track the reach of skyglow from a peri-urban into a remote area on a clear and a partly cloudy night by performing transects from the Spanish town of Balaguer towards Montsec Astronomical Park. From one single all-sky image, we extract zenith luminance, horizontal and scalar illuminance. While zenith luminance reaches near-natural levels at 5 km distance from the town on the clear night, similar levels are only reached at 27 km on the partly cloudy night. Our results show the dramatic increase of the reach of skyglow even for moderate cloud coverage at this site. The powerful and easy-to-use method promises to be widely applicable for studies of ecological light pollution on a global scale also by non-specialists in photometry.

  19. Adnyamathanha Night Skies

    Science.gov (United States)

    Curnow, Paul

    2009-06-01

    Aboriginal Australians have been viewing the night skies of Australia for some 45,000 years and possibly much longer. During this time they have been able to develop a complex knowledge of the night sky, the terrestrial environment in addition to seasonal changes. However, few of us in contemporary society have an in-depth knowledge of the nightly waltz of stars above.

  20. Enhanced solar global irradiance during cloudy sky conditions

    Energy Technology Data Exchange (ETDEWEB)

    Schade, N.H.; Sandmann, H.; Stick, C. [Kiel Univ. (Germany). Inst. fuer Medizinische Klimatologie; Macke, A. [Kiel Univ. (DE). Leibniz Inst. fuer Meereswissenschaften (IFM-GEOMAR)

    2007-06-15

    The impact of cloudiness on the shortwave downwelling radiation (SDR) at the surface is investigated by means of collocated pyranometer radiation measurements and all-sky imager observations. The measurements have been performed in Westerland, a seaside resort on the North Sea island of Sylt, Germany, during summer 2004 and 2005. A main improvement to previous studies on this subject resulted from the very high temporal resolution of cloud images and radiation measurements and, therefore, a more robust statistical analysis of the occurrence of this effect. It was possible to observe an excess of solar irradiation compared to clear sky irradiation by more than 500 W/m{sup 2}, the largest observed excess irradiation to our knowledge so far. Camera images reveal that largest excess radiation is reached close to overcast situations with altocumulus clouds partly obscuring the solar disk, and preferably with cumulus clouds in lower levels. The maximum duration of the enhancements depends on its strength and ranges from 20 seconds (enhancements > 400 W/m{sup 2}) up to 140 seconds (enhancements > 200 W/m{sup 2}). (orig.)

  1. 78 FR 54507 - Clearing Agency; the Options Clearing Corporation; Notice of Filing of Proposed Rule Change To...

    Science.gov (United States)

    2013-09-04

    ... risk arising from the potential need to liquidate a particular clearing member's margin collateral, OCC... by improving OCC's risk management process related to deposits as margin collateral of concentrated... and Policy so that OCC has discretion to disapprove as margin collateral for a particular clearing...

  2. INLUX-DBR - A calculation code to calculate indoor natural illuminance inside buildings under various sky conditions

    International Nuclear Information System (INIS)

    Ferraro, V.; Igawa, N.; Marinelli, V.

    2010-01-01

    A calculation code, named INLUX-DBR, is presented, which is a modified version of INLUX code, able to predict the illuminance distribution on the inside surfaces of a room with six walls and a window, and on the work plane. At each desired instant the code solves the system of the illuminance equations of each surface element, characterized by the latter's reflection coefficient and its view factors toward the other elements. In the model implemented in the code, the sky-diffuse luminance distribution, the sun beam light and the light reflected from the ground toward the room are considered. The code was validated by comparing the calculated values of illuminance with the experimental values measured inside a scale model (1:5) of a building room, in various sky conditions of overcast, clear and intermediate days. The validation is performed using the sky luminance data measured by a sky scanner and the measured beam illuminance of the sun as input data. A comparative analysis of some of the well-known calculation models of sky luminance, namely Perez, Igawa and CIE models was also carried out, comparing the code predictions and the measured values of inside illuminance in the scale model.

  3. Inferences of all-sky solar irradiance using Terra and Aqua MODIS satellite data

    DEFF Research Database (Denmark)

    Houborg, Rasmus Møller; Søgaard, Henrik; Emmerich, W.

    2007-01-01

    -sky solar irradiance components, which links a physically based clear-sky model with a neural network version of a rigorous radiative transfer model. The scheme exploits the improved cloud characterization and retrieval capabilities of the MODerate resolution Imaging Spectroradiometer (MODIS) onboard...... contrasting climates and cloud environments. Information on the atmospheric state was provided by MODIS data products and verifications against AErosol RObotic NETwork (AERONET) data demonstrated usefulness of MODIS aerosol optical depth and total precipitable water vapour retrievals for the delineation...... and become unusable above approximately 60° latitude. However, in principle, the scheme can be applied anywhere on the globe, and a synergistic use of MODIS and geostationary satellite datasets may be envisaged for some applications....

  4. Causality and skies: is non-refocussing necessary?

    International Nuclear Information System (INIS)

    Bautista, A; Ibort, A; Lafuente, J

    2015-01-01

    The causal structure of a strongly causal, null pseudo-convex, space-time M is completely characterized in terms of a partial order on its space of skies defined by means of a class of non-negative Legendrian isotopies called sky isotopies. It is also shown that such partial order is determined by the class of future causal celestial curves, that is, curves in the space of light rays which are tangent to skies and such that they determine non-negative sky isotopies. It will also be proved that the space of skies Σ equipped with Low’s (or reconstructive) topology is homeomorphic and diffeomorphic to M under the only additional assumption that M separates skies, that is, that different events determine different skies. The sky-separating property of M is sharp and the previous result provides an answer to the question about the class of space-times whose causal structure, topological and differentiable structure can be reconstructed from their spaces of light rays and skies. These results can be understood as a Malament–Hawking-like theorem stated in terms of the partial order defined on the space of skies. (paper)

  5. Dark-Skies Awareness

    Science.gov (United States)

    Walker, Constance E.

    2009-05-01

    The arc of the Milky Way seen from a truly dark location is part of our planet's natural heritage. More than one fifth of the world population, two thirds of the United States population and one half of the European Union population have already lost naked eye visibility of the Milky Way. This loss, caused by light pollution, is a serious and growing issue that impacts astronomical research, the economy, ecology, energy conservation, human health, public safety and our shared ability to see the night sky. For this reason, "Dark Skies” is a cornerstone project of the International Year of Astronomy. Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people worldwide involved in a variety of programs that: 1. Teach about dark skies using new technology (e.g., an activity-based planetarium show on DVD, podcasting, social networking on Facebook and MySpace, a Second Life presence) 2. Provide thematic events on light pollution at star parties and observatory open houses (Dark Skies Discovery Sites, Nights in the (National) Parks, Sidewalk Astronomy) 3. Organize events in the arts (e.g., a photography contest) 4. Involve citizen-scientists in naked-eye and digital-meter star hunting programs (e.g., GLOBE at Night, "How Many Stars?", the Great World Wide Star Count and the radio frequency interference equivalent: "Quiet Skies") and 5. Raise awareness about the link between light pollution and public health, economic issues, ecological consequences, energy conservation, safety and security, and astronomy (e.g., The Starlight Initiative, World Night in Defense of Starlight, International Dark Sky Week, International Dark-Sky Communities, Earth Hour, The Great Switch Out, a traveling exhibit, downloadable posters and brochures). The presentation will provide an update, describe how people can become involved and take a look ahead at the program's sustainability. For more information, visit www.darkskiesawareness.org.

  6. 2014 Australasian sky guide

    CERN Document Server

    Lomb, Nick

    2013-01-01

    Compact, easy to use and reliable, this popular guide contains everything you need to know about the southern night sky with monthly astronomy maps, viewing tips and highlights, and details of all the year's exciting celestial events. Wherever you are in Australia or New Zealand, easy calculations allow you to estimate local rise and set times for the Sun, Moon and planets. The 2014 Australasian Sky Guide also provides information on the solar system, updated with the latest findings from space probes. Published annually since 1991, the Sky Guide continues to be a favourite with photographers,

  7. Dark Skies as a Universal Resource: Citizen Scientists Measuring Sky Brightness

    Science.gov (United States)

    Walker, C. E.; Isbell, D.; Pompea, S. M.

    2007-12-01

    The international star-hunting event known as GLOBE at Night returned March 8-21, 2007 in two flavors: the classic GLOBE at Night activity incorporating unaided-eye observations which debuted last year, and a new effort to obtain precise measurements of urban dark skies using digital sky-brightness meters. Both flavors of the program were designed to aid in heightening the awareness about the impact of artificial lighting on local environments, and the ongoing loss of a dark night sky as a natural resource for much of the world's population. To make possible the digital GLOBE at Night program, NSF funded 135 low-cost, digital sky-quality meter (manufactured by Unihedron). With these, citizen-scientists took direct measurements of the integrated sky brightness across a wide swath of night sky. Along with related materials developed by the National Optical Astronomy Observatory (NOAO), the meters were distributed to citizen-scientists in 21 U.S. states plus Washington DC, and in 5 other countries, including Chile, where NOAO has a major observatory. The citizen- scientists were selected from teachers, their students, astronomers at mountain-top observatories, International Dark-Sky Association members and staff from 19 small science centers. Most sites had a coordinator, who instructed local educators in the proper use of the meters and develop a plan to share them as widely as possible during the 2-week window. The local teams pooled their data for regional analysis and in some cases shared the results with their schools and local policymakers. Building upon the worldwide participation sparked by the first GLOBE at Night campaign in March 2006, the observations this year approached 8500 (from 60 countries), 85% higher than the number from last year. The success of GLOBE at Night 2007 is a major step toward the International Year of Astronomy in 2009, when one goal is to make the digital data collection into a worldwide activity. In this presentation, we will outline

  8. Light pollution: Assessment of sky glow on two dark sky regions of Portugal.

    Science.gov (United States)

    Lima, Raul Cerveira; Pinto da Cunha, José; Peixinho, Nuno

    2016-01-01

    Artificial light at night (ALAN), producing light pollution (LP), is not a matter restricted to astronomy anymore. Light is part of modern societies and, as a consequence, the natural cycle day-night (bright-dark) has been interrupted in a large segment of the global population. There is increasing evidence that exposure to certain types of light at night and beyond threshold levels may produce hazardous effects to humans and the environment. The concept of "dark skies reserves" is a step forward in order to preserve the night sky and a means of enhancing public awareness of the problem of spread of light pollution worldwide. The aim of this study was to assess the skyglow at two sites in Portugal, the Peneda-Gerês National Park (PNPG) and the region now known as Dark Sky Alqueva Reserve. The latter site was classified as a "Starlight Tourism Destination" by the Starlight Foundation (the first in the world to achieve this classification) following a series of night sky measurements in situ described herein. The measurements at PNPG also contributed to the new set of regulations concerning light pollution at this national park. This study presents the first in situ systematic measurements of night sky brightness, showing that at the two sites the skies are mostly in levels 3 to 4 of the Bortle 9-level scale (with level 1 being the best achievable). The results indicate that the sources of light pollution and skyglow can be attributed predominantly to contamination from nearby urban regions.

  9. Education for Life in the Sky.

    Science.gov (United States)

    Roth, Charles E.

    1981-01-01

    The need to educate people about the sky as both a psychological and physical environment is discussed, including a formal curriculum schema (sky as habitat, sky as transport, influence on culture) and informal curriculum, with such topics as recreation, pollution, mythology, and clouds. (DC)

  10. 77 FR 66209 - Self-Regulatory Organizations; ICE Clear Europe Limited; Notice of Filing of Proposed Rule Change...

    Science.gov (United States)

    2012-11-02

    ... SECURITIES AND EXCHANGE COMMISSION [Release No. 34-68119; File No. SR-ICEEU-2012-08)] Self... way risk'' involving correlation between the risk of default of an underlying sovereign and the risk..., including back tests and stress tests. ICE Clear Europe believes that the proposed rule change to add New...

  11. CMB spectra and bispectra calculations: making the flat-sky approximation rigorous

    International Nuclear Information System (INIS)

    Bernardeau, Francis; Pitrou, Cyril; Uzan, Jean-Philippe

    2011-01-01

    This article constructs flat-sky approximations in a controlled way in the context of the cosmic microwave background observations for the computation of both spectra and bispectra. For angular spectra, it is explicitly shown that there exists a whole family of flat-sky approximations of similar accuracy for which the expression and amplitude of next to leading order terms can be explicitly computed. It is noted that in this context two limiting cases can be encountered for which the expressions can be further simplified. They correspond to cases where either the sources are localized in a narrow region (thin-shell approximation) or are slowly varying over a large distance (which leads to the so-called Limber approximation). Applying this to the calculation of the spectra it is shown that, as long as the late integrated Sachs-Wolfe contribution is neglected, the flat-sky approximation at leading order is accurate at 1% level for any multipole. Generalization of this construction scheme to the bispectra led to the introduction of an alternative description of the bispectra for which the flat-sky approximation is well controlled. This is not the case for the usual description of the bispectrum in terms of reduced bispectrum for which a flat-sky approximation is proposed but the next-to-leading order terms of which remain obscure

  12. 76 FR 45724 - Clearing Member Risk Management

    Science.gov (United States)

    2011-08-01

    ... proposed rules address risk management for cleared trades by futures commission merchants, swap dealers... Commission has proposed extensive regulations addressing open access and risk management at the derivatives..., 2011) (Risk Management Requirements for Derivatives Clearing Organizations). These proposed regulations...

  13. NASA Science Engagement Through "Sky Art"

    Science.gov (United States)

    Bethea, K. L.; Damadeo, K.

    2013-12-01

    Sky Art is a NASA-funded online community where the public can share in the beauty of nature and the science behind it. At the center of Sky Art is a gallery of amateur sky photos submitted by users that are related to NASA Earth science mission research areas. Through their submissions, amateur photographers from around the world are engaged in the process of making observations, or taking pictures, of the sky just like many NASA science instruments. By submitting their pictures and engaging in the online community discussions and interactions with NASA scientists, users make the connection between the beauty of nature and atmospheric science. Sky Art is a gateway for interaction and information aimed at drawing excitement and interest in atmospheric phenomena including sunrises, sunsets, moonrises, moonsets, and aerosols, each of which correlates to a NASA science mission. Educating the public on atmospheric science topics in an informal way is a central goal of Sky Art. NASA science is included in the community through interaction from scientists, NASA images, and blog posts on science concepts derived from the images. Additionally, the website connects educators through the formal education pathway where science concepts are taught through activities and lessons that align with national learning standards. Sky Art was conceived as part of the Education and Public Outreach program of the SAGE III on ISS mission. There are currently three other NASA mission involved with Sky Art: CALIPSO, GPM, and CLARREO. This paper will discuss the process of developing the Sky Art online website, the challenges of growing a community of users, as well as the use of social media and mobile applications in science outreach and education.

  14. 76 FR 55984 - Self-Regulatory Organizations; ICE Clear Credit LLC; Notice of Filing of Proposed Rule Change To...

    Science.gov (United States)

    2011-09-09

    ... on sovereign reference entities, including back tests and stress tests using actual clearing participant portfolios (with respect to the stress tests) combined with hypothetical positions in sovereign... submit written data, views, and arguments concerning the foregoing, including whether the proposed rule...

  15. INLUX-DBR - A calculation code to calculate indoor natural illuminance inside buildings under various sky conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ferraro, V.; Igawa, N.; Marinelli, V. [Mechanical Engineering Department, University of Calabria, 87036 Arcavacata di Rende (CS) (Italy)

    2010-09-15

    A calculation code, named INLUX-DBR, is presented, which is a modified version of INLUX code, able to predict the illuminance distribution on the inside surfaces of a room with six walls and a window, and on the work plane. At each desired instant the code solves the system of the illuminance equations of each surface element, characterized by the latter's reflection coefficient and its view factors toward the other elements. In the model implemented in the code, the sky-diffuse luminance distribution, the sun beam light and the light reflected from the ground toward the room are considered. The code was validated by comparing the calculated values of illuminance with the experimental values measured inside a scale model (1:5) of a building room, in various sky conditions of overcast, clear and intermediate days. The validation is performed using the sky luminance data measured by a sky scanner and the measured beam illuminance of the sun as input data. A comparative analysis of some of the well-known calculation models of sky luminance, namely Perez, Igawa and CIE models was also carried out, comparing the code predictions and the measured values of inside illuminance in the scale model. (author)

  16. Effect of the position of the visible sky in determining the sky view factor on micrometeorological and human thermal comfort conditions in urban street canyons

    Science.gov (United States)

    Qaid, Adeb; Lamit, Hasanuddin Bin; Ossen, Dilshan Remaz; Rasidi, Mohd Hisyam

    2018-02-01

    Poor daytime and night-time micrometeorological conditions are issues that influence the quality of environmental conditions and can undermine a comfortable human lifestyle. The sky view factor (SVF) is one of the essential physical parameters used to assess the micrometeorological conditions and thermal comfort levels within city streets. The position of the visible sky relative to the path of the sun, in the cardinal and ordinal directions, has not been widely discerned as a parameter that could have an impact on the micrometeorological conditions of urban streets. To investigate this parameter, different urban streets that have a similar SVF value but diverse positions of visible sky were proposed in different street directions intersecting with the path of the sun, namely N-S, NE-SW and NW-SE. The effects of daytime and night-time micrometeorological variables and human thermal comfort variables on the street were investigated by applying ENVI-met V3.1 Beta software. The results show that the position of the visible sky has a greater influence on the street's meteorological and human thermal comfort conditions than the SVF value. It has the ability to maximise or minimise the mean radiation temperature (Tmrt, °C) and the physiological equivalent temperature (PET, °C) at street level. However, the visible sky positioned to the zenith in a NE-SW or N-S street direction and to the SW of a NW-SE street direction achieves the best daytime micrometeorological and thermal comfort conditions. Alternatively, the visible sky positioned to the NE for a NW-SE street direction, to the NW and the zenith for a NE-SW street direction and to the zenith for a N-S street direction reduces the night-time air temperature (Ta, °C). Therefore, SVF and the position of the visible sky relative to the sun's trajectory, in the cardinal and ordinal directions, must be considered during urban street planning to better understand the resultant micrometeorological and human thermal

  17. Fireballs in the Sky

    Science.gov (United States)

    Day, B. H.; Bland, P.

    2016-12-01

    Fireballs in the Sky is an innovative Australian citizen science program that connects the public with the research of the Desert Fireball Network (DFN). This research aims to understand the early workings of the solar system, and Fireballs in the Sky invites people around the world to learn about this science, contributing fireball sightings via a user-friendly app. To date, more than 23,000 people have downloaded the app world-wide and participated in planetary science. The Fireballs in the Sky app allows users to get involved with the Desert Fireball Network research, supplementing DFN observations and providing enhanced coverage by reporting their own meteor sightings to DFN scientists. Fireballs in the Sky reports are used to track the trajectories of meteors - from their orbit in space to where they might have landed on Earth. Led by Phil Bland at Curtin University in Australia, the Desert Fireball Network (DFN) uses automated observatories across Australia to triangulate trajectories of meteorites entering the atmosphere, determine pre-entry orbits, and pinpoint their fall positions. Each observatory is an autonomous intelligent imaging system, taking 1000×36Megapixel all-sky images throughout the night, using neural network algorithms to recognize events. They are capable of operating for 12 months in a harsh environment, and store all imagery collected. We developed a completely automated software pipeline for data reduction, and built a supercomputer database for storage, allowing us to process our entire archive. The DFN currently stands at 50 stations distributed across the Australian continent, covering an area of 2.5 million km^2. Working with DFN's partners at NASA's Solar System Exploration Research Virtual Institute, the team is expanding the network beyond Australia to locations around the world. Fireballs in the Sky allows a growing public base to learn about and participate in this exciting research.

  18. TWO MICRON ALL SKY SURVEY PHOTOMETRIC REDSHIFT CATALOG: A COMPREHENSIVE THREE-DIMENSIONAL CENSUS OF THE WHOLE SKY

    International Nuclear Information System (INIS)

    Bilicki, Maciej; Jarrett, Thomas H.; Cluver, Michelle E.; Steward, Louise; Peacock, John A.

    2014-01-01

    Key cosmological applications require the three-dimensional (3D) galaxy distribution on the entire celestial sphere. These include measuring the gravitational pull on the Local Group, estimating the large-scale bulk flow, and testing the Copernican principle. However, the largest all-sky redshift surveys—the 2MASS Redshift Survey and IRAS Point Source Catalog Redshift Survey—have median redshifts of only z = 0.03 and sample the very local universe. All-sky galaxy catalogs exist that reach much deeper—SuperCOSMOS in the optical, the Two Micron All Sky Survey (2MASS) in the near-IR, and WISE in the mid-IR—but these lack complete redshift information. At present, the only rapid way toward larger 3D catalogs covering the whole sky is through photometric redshift techniques. In this paper we present the 2MASS Photometric Redshift catalog (2MPZ) containing one million galaxies, constructed by cross-matching Two Micron All Sky Survey Extended Source Catalog (2MASS XSC), WISE, and SuperCOSMOS all-sky samples and employing the artificial neural network approach (the ANNz algorithm), trained on such redshift surveys as the Sloan Digital Sky Survey, 6dFGS, and 2dFGRS. The derived photometric redshifts have errors nearly independent of distance, with an all-sky accuracy of σ z = 0.015 and a very small percentage of outliers. In this way, we obtain redshift estimates with a typical precision of 12% for all the 2MASS XSC galaxies that lack spectroscopy. In addition, we have made an early effort toward probing the entire 3D sky beyond 2MASS, by pairing up WISE with SuperCOSMOS and training the ANNz on GAMA redshift data currently reaching to z med ∼ 0.2. This has yielded photo-z accuracies comparable to those in the 2MPZ. These all-sky photo-z catalogs, with a median z ∼ 0.1 for the 2MPZ, and significantly deeper for future WISE-based samples, will be the largest and most complete of their kind for the foreseeable future

  19. Night sky a falcon field guide

    CERN Document Server

    Nigro, Nicholas

    2012-01-01

    Night Sky: A Falcon Field Guide covers both summer and winter constellations, planets, and stars found in the northern hemisphere. Conveniently sized to fit in a pocket and featuring detailed photographs, this informative guide makes it easy to identify objects in the night sky even from one's own backyard. From information on optimal weather conditions, preferred viewing locations, and how to use key tools of the trade, this handbook will help you adeptly navigate to and fro the vast and dynamic nighttime skies, and you'll fast recognize that the night sky's the limit.

  20. Systematic measurements of the night sky brightness at 26 locations in Eastern Austria

    Science.gov (United States)

    Posch, Thomas; Binder, Franz; Puschnig, Johannes

    2018-05-01

    We present an analysis of the zenithal night sky brightness (henceforth: NSB) measurements at 26 locations in Eastern Austria focussing on the years 2015-2016, both during clear and cloudy to overcast nights. All measurements have been performed with 'Sky Quality Meters' (SQMs). For some of the locations, simultaneous aerosol content measurements are available, such that we were able to find a correlation between light pollution and air pollution at those stations. For all locations, we examined the circalunar periodicity of the NSB, seasonal variations as well as long-term trends in the recorded light pollution. The latter task proved difficult, however, due to varying meteorological conditions, potential detector 'aging' and other effects. For several remote locations, a darkening of the overcast night sky by up to 1 magnitude is recorded - indicating a very low level of light pollution -, while for the majority of the examined locations, a brightening of the night sky by up to a factor of 15 occurs due to clouds. We present suitable ways to plot and analyze huge long-term NSB datasets, such as mean-NSB histograms, circalunar, annual ('hourglass') and cumulative ('jellyfish') plots. We show that five of the examined locations reach sufficiently low levels of light pollution - with NSB values down to 21.8 magSQM/arcsec2 - as to allow the establishment of dark sky reserves, even to the point of reaching the 'gold tier' defined by the International Dark Sky Association. Based on the 'hourglass' plots, we find a strong circalunar periodicity of the NSB in small towns and villages ( < 5.000 inhabitants), with amplitudes of up to 5 magnitudes. Using the 'jellyfish' plots, on the other hand, we demonstrate that the examined city skies brighten by up to 3 magnitudes under cloudy conditions, which strongly dominate in those cumulative data representations. Nocturnal gradients of the NSB of 0.0-0.14 magSQM/arcsec2/h are found. The long-term development of the night sky

  1. Alaskan Auroral All-Sky Images on the World Wide Web

    Science.gov (United States)

    Stenbaek-Nielsen, H. C.

    1997-01-01

    In response to a 1995 NASA SPDS announcement of support for preservation and distribution of important data sets online, the Geophysical Institute, University of Alaska Fairbanks, Alaska, proposed to provide World Wide Web access to the Poker Flat Auroral All-sky Camera images in real time. The Poker auroral all-sky camera is located in the Davis Science Operation Center at Poker Flat Rocket Range about 30 miles north-east of Fairbanks, Alaska, and is connected, through a microwave link, with the Geophysical Institute where we maintain the data base linked to the Web. To protect the low light-level all-sky TV camera from damage due to excessive light, we only operate during the winter season when the moon is down. The camera and data acquisition is now fully computer controlled. Digital images are transmitted each minute to the Web linked data base where the data are available in a number of different presentations: (1) Individual JPEG compressed images (1 minute resolution); (2) Time lapse MPEG movie of the stored images; and (3) A meridional plot of the entire night activity.

  2. Promoting Dark Sky Protection in Chile: the Gabriel Mistral IDA Dark Sky Sanctuary and Other AURA Initiatives

    Science.gov (United States)

    Smith, R. Chris; Smith, Malcolm; Pompea, Stephen; Sanhueza, Pedro; AURA-Chile EPO Team

    2018-01-01

    For over 20 years, AURA has been leading efforts promoting the protection of dark skies in northern Chile. Efforts began in the early 1990s at AURA's Cerro Tololo Inter-American Observatory (CTIO), working in collaboration with other international observatories in Chile including Las Campanas Observatory (LCO) and the European Southern Observatory (ESO). CTIO also partnered with local communities, for example supporting Vicuña's effort to establish the first municipal observatory in Chile. Today we have developed a multifaceted effort of dark sky protection, including proactive government relations at national and local levels, a strong educational and public outreach program, and a program of highlighting international recognition of the dark skies through the IDA Dark Sky Places program. Work on international recognition has included the declaration of the Gabriel Mistral IDA Dark Sky Sanctuary, the first such IDA sanctuary in the world.

  3. A Chinese sky trust?

    Energy Technology Data Exchange (ETDEWEB)

    Brenner, Mark [Political Economy Research Institute, University of Massachusetts, Amherst (United States)]. E-mail: brenner@econs.umass.edu; Riddle, Matthew [Department of Economics, University of Massachusetts, Amherst (United States)]. E-mail: mriddle@econs.umass.edu; Boyce, James K. [Political Economy Research Institute and Department of Economics, University of Massachusetts, Amherst (United States)]. E-mail: boyce@econs.umass.edu

    2007-03-15

    The introduction of carbon charges on the use of fossil fuels in China would have a progressive impact on income distribution. This outcome, which contrasts to the regressive distributional impact found in most studies of carbon charges in industrialized countries, is driven primarily by differences between urban and rural expenditure patterns. If carbon revenues were recycled on an equal per capita basis via a 'sky trust,' the progressive impact would be further enhanced: low-income (mainly rural) households would receive more in sky-trust dividends than they pay in carbon charges, and high-income (mainly urban) households would pay more than they receive in dividends. Thus a Chinese sky trust would contribute to both lower fossil fuel consumption and greater income equality.

  4. A Chinese sky trust?

    International Nuclear Information System (INIS)

    Brenner, Mark; Riddle, Matthew; Boyce, James K.

    2007-01-01

    The introduction of carbon charges on the use of fossil fuels in China would have a progressive impact on income distribution. This outcome, which contrasts to the regressive distributional impact found in most studies of carbon charges in industrialized countries, is driven primarily by differences between urban and rural expenditure patterns. If carbon revenues were recycled on an equal per capita basis via a 'sky trust,' the progressive impact would be further enhanced: low-income (mainly rural) households would receive more in sky-trust dividends than they pay in carbon charges, and high-income (mainly urban) households would pay more than they receive in dividends. Thus a Chinese sky trust would contribute to both lower fossil fuel consumption and greater income equality

  5. Estimation of spectral distribution of sky radiance using a commercial digital camera.

    Science.gov (United States)

    Saito, Masanori; Iwabuchi, Hironobu; Murata, Isao

    2016-01-10

    Methods for estimating spectral distribution of sky radiance from images captured by a digital camera and for accurately estimating spectral responses of the camera are proposed. Spectral distribution of sky radiance is represented as a polynomial of the wavelength, with coefficients obtained from digital RGB counts by linear transformation. The spectral distribution of radiance as measured is consistent with that obtained by spectrometer and radiative transfer simulation for wavelengths of 430-680 nm, with standard deviation below 1%. Preliminary applications suggest this method is useful for detecting clouds and studying the relation between irradiance at the ground and cloud distribution.

  6. SkyNet: Modular nuclear reaction network library

    Science.gov (United States)

    Lippuner, Jonas; Roberts, Luke F.

    2017-10-01

    The general-purpose nuclear reaction network SkyNet evolves the abundances of nuclear species under the influence of nuclear reactions. SkyNet can be used to compute the nucleosynthesis evolution in all astrophysical scenarios where nucleosynthesis occurs. Any list of isotopes can be evolved and SkyNet supports various different types of nuclear reactions. SkyNet is modular, permitting new or existing physics, such as nuclear reactions or equations of state, to be easily added or modified.

  7. Validation of a spectral correction procedure for sun and sky reflections in above-water reflectance measurements.

    Science.gov (United States)

    Groetsch, Philipp M M; Gege, Peter; Simis, Stefan G H; Eleveld, Marieke A; Peters, Steef W M

    2017-08-07

    A three-component reflectance model (3C) is applied to above-water radiometric measurements to derive remote-sensing reflectance Rrs (λ). 3C provides a spectrally resolved offset Δ(λ) to correct for residual sun and sky radiance (Rayleigh- and aerosol-scattered) reflections on the water surface that were not represented by sky radiance measurements. 3C is validated with a data set of matching above- and below-water radiometric measurements collected in the Baltic Sea, and compared against a scalar offset correction Δ. Correction with Δ(λ) instead of Δ consistently reduced the (mean normalized root-mean-square) deviation between Rrs (λ) and reference reflectances to comparable levels for clear (Δ: 14.3 ± 2.5 %, Δ(λ): 8.2 ± 1.7 %), partly clouded (Δ: 15.4 ± 2.1 %, Δ(λ): 6.5 ± 1.4 %), and completely overcast (Δ: 10.8 ± 1.7 %, Δ(λ): 6.3 ± 1.8 %) sky conditions. The improvement was most pronounced under inhomogeneous sky conditions when measurements of sky radiance tend to be less representative of surface-reflected radiance. Accounting for both sun glint and sky reflections also relaxes constraints on measurement geometry, which was demonstrated based on a semi-continuous daytime data set recorded in a eutrophic freshwater lake in the Netherlands. Rrs (λ) that were derived throughout the day varied spectrally by less than 2 % relative standard deviation. Implications on measurement protocols are discussed. An open source software library for processing reflectance measurements was developed and is made publicly available.

  8. VLITE Surveys the Sky: A 340 MHz Companion to the VLA Sky Survey (VLASS)

    Science.gov (United States)

    Peters, Wendy; Clarke, Tracy; Brisken, Walter; Cotton, William; Richards, Emily E.; Giacintucci, Simona; Kassim, Namir

    2018-01-01

    The VLA Low Band Ionosphere and Transient Experiment (VLITE; ) is a commensal observing system on the Karl G. Janksy Very Large Array (VLA) which was developed by the Naval Research Laboratory and NRAO. A 64 MHz sub-band from the prime focus 240-470 MHz dipoles is correlated during nearly all regular VLA observations. VLITE uses dedicated samplers and fibers, as well as a custom designed, real-time DiFX software correlator, and requires no additional resources from the VLA system running the primary science program. The experiment has been operating since November 2014 with 10 antennas; a recent expansion in summer 2017 increased that number to 16 and more than doubled the number of baselines.The VLA Sky Survey (VLASS; ), is an ongoing survey of the entire sky visible to the VLA at a frequency of 2-4 GHz. The observations are made using an "on-the-fly" (OTF) continuous RA scanning technique which fills in the sky by observing along rows of constant declination. VLITE breaks the data into 2-second integrations and correlates these at a central position every 1.5 degrees. All data for each correlator position is imaged separately, corrected and weighted by an appropriately elongated primary beam model, and then combined in the image plane to create a mosaic of the sky. A catalog of the sources is extracted to provide a 340 MHz sky model.We present preliminary images and catalogs from the 2017 VLASS observations which began in early September, 2017, and continued on a nearly daily basis throughout the fall. In addition to providing a unique sky model at 340 MHz, these data complement VLASS by providing spectral indices for all cataloged sources.

  9. Solar irradiance forecasting at one-minute intervals for different sky conditions using sky camera images

    International Nuclear Information System (INIS)

    Alonso-Montesinos, J.; Batlles, F.J.; Portillo, C.

    2015-01-01

    Highlights: • The solar resource has been predicted for three hours at 1-min intervals. • Digital image levels and cloud motion vectors are joint for irradiance forecasting. • The three radiation components have been predicted under different sky conditions. • Diffuse and global radiation has an nRMSE value around 10% in all sky conditions. • Beam irradiance is predicted with an nRMSE value of about 15% in overcast skies. - Abstract: In the search for new techniques to predict atmospheric features that might be useful to solar power plant operators, we have carried out solar irradiance forecasting using emerging sky camera technology. Digital image levels are converted into irradiances and then the maximum cross-correlation method is applied to obtain future predictions. This methodology is a step forward in the study of the solar resource, essential to solar plant operators in adapting a plant’s operating procedures to atmospheric conditions and to improve electricity generation. The results are set out using different statistical parameters, in which beam, diffuse and global irradiances give a constant normalized root-mean-square error value over the time interval for all sky conditions. The average measure is 25.44% for beam irradiance; 11.60% for diffuse irradiance and 11.17% for global irradiance.

  10. Daytime Water Detection Based on Sky Reflections

    Science.gov (United States)

    Rankin, Arturo; Matthies, Larry; Bellutta, Paolo

    2011-01-01

    A water body s surface can be modeled as a horizontal mirror. Water detection based on sky reflections and color variation are complementary. A reflection coefficient model suggests sky reflections dominate the color of water at ranges > 12 meters. Water detection based on sky reflections: (1) geometrically locates the pixel in the sky that is reflecting on a candidate water pixel on the ground (2) predicts if the ground pixel is water based on color similarity and local terrain features. Water detection has been integrated on XUVs.

  11. Piero della Francesca's Sky in The Dream of Constantine

    Science.gov (United States)

    Valerio, V.

    2011-06-01

    The recent restoration of the frescoes by Piero della Francesca in the Church of San Francesco in Arezzo has made to appear on the background of the scene of Constantine's dream a number of stars. They are clearly painted with the intention to illustrate a sort of "natural" sky. In 2001 Anna Maria Maetzke recognized in a group of stars the constellation of the Ursa Minor, but so far no further study has been carried on to find any relation between the painted and the true sky. In this paper I show the existence of more constellations in the fresco, which are hardly detectable due to the mirror representation of the starry sky. Such a mirror image, as the Universe was seen from the outside, has a Greek origin and this kind of representation was introduced in Western Europe not only in celestial globes but also in star maps. This discovery leads to consider that Piero had at his disposal either a globe or a map which he reproduced on the fresco. My hypothesis is that a star map might be supplied to Piero by the astronomer Regiomontanus who was in Italy since 1461 following the Cardinal Bessarion in his journey from Wien to Rome. In 1463, Cardinal Bessarion was named papal legate to Venice and in July of the same year he leaved Rome together with Regiomontanus to reach Ferrara and Venice. The road to Venice crossed Umbria nearby Sansepolcro, Piero's birthplace not far from Arezzo. The trip took more than two weeks due to a stop before crossing the Apennines because the plague in Ferrara. Bessarion and Regiomontanus might have met Piero who was painting the cycle of frescoes in Arezzo and supplied him with a star map. Unfortunately, due to the lack of the horizon and any right line in the scene it is not possible to detect the latitude of the place corresponding to the painted sky.

  12. Educating for the Preservation of Dark Skies

    Science.gov (United States)

    Preston, Sandra Lee; Cianciolo, Frank; Wetzel, Marc; Finkelstein, Keely; Wren, William; Nance, Craig

    2015-08-01

    The stars at night really are big and bright deep in the heart of Texas at the McDonald Observatory near Fort Davis, Texas. Each year 80,000 visitors from all over the world make the pilgrimage to the Observatory to attend one of the three-times-a-week star parties. Many experience, for the first time, the humbling, splendor of a truly dark night sky. Over the last several years, the Observatory has experienced dramatic increases in visitation demonstrating the public’s appetite for science education, in general, and interest in the night sky, in particular. This increasing interest in astronomy is, ironically, occurring at a time when most of humanity’s skies are becoming increasingly light-polluted frustrating this natural interest. Dark skies and knowledgeable education and outreach staff are an important resource in maintaining the public’s interest in astronomy, support for astronomical research, and local tourism.This year Observatory educators were inspired by the observance of the International Year of Light to promote healthy outdoor lighting through its popular Astronomy Day distance learning program. This program reaches tens of thousands of K-12 students in Texas and other states with a message of how they can take action to preserve dark skies. As well, more than a thousand Boy Scouts visiting during the summer months receive a special program, which includes activities focusing on good lighting practices, thereby earning them credits toward an astronomy badge.The Observatory also offers a half-a-dozen K-12 teacher professional development workshops onsite each year, which provide about 90 teachers with dark skies information, best-practice lighting demonstrations, and red flashlights. Multi-year workshops for National Park and State of Texas Parks personnel are offered on dark sky preservation and sky interpretation at McDonald and a Dark Skies fund for retrofitting lights in the surrounding area has been established. The Observatory also uses

  13. Análise da frequência anual das condições de céu em Botucatu, São Paulo Analysis of the annual frequency of the sky conditions in Botucatu, São Paulo

    Directory of Open Access Journals (Sweden)

    Érico T. Teramoto

    2012-09-01

    Full Text Available Este trabalho apresenta uma análise da frequência das condições de céu em Botucatu. A classificação das condições de céu foi feita com base no índice de claridade (K T, calculado a partir de uma base de dados de 10 anos de radiação global diária. Em Botucatu há, ao longo do ano, predominância de dias com condição de céu claro, em média 114 dias. Para a condição de céu nebuloso a frequência média é de 61 dias e, em referência às duas condições de céu intermediárias, a frequência de céu parcialmente nebuloso com dominância para o difuso, é de 94 dias e a com dominância para o claro é de 96 dias. Os principais fatores influentes sobre as condições de céu em Botucatu são as entradas de frentes frias e a formação da Zona de Convergência do Atlântico Sul, as quais respondem principalmente pela alteração da condição de céu claro para a de céu nebuloso ou para a de céu parcialmente nebuloso com dominância para o difuso. Os aerossóis resultantes das queimadas em lavouras de cana-de-açúcar respondem pela alteração da condição de céu claro para a de céu parcialmente nebuloso com dominância para o claro.This paper presents an analysis of the frequency of the sky conditions in Botucatu. The classification of sky conditions was made based on the clearness index (K T, calculated from a database with 10 years of measured daily global solar radiation. Throughout the year in Botucatu, there is a predominance of days with clear sky condition, on average 114 days. For cloudy sky condition, the average frequency is 61 days. About the two intermediate sky conditions, the frequency of the sky partially cloudy with dominance for the diffuse is 94 days and the one with dominance for the clear is 96 days. The main influential factors on the sky conditions in Botucatu are the inputs of cold fronts and the formation of the South Atlantic Convergence Zone. They respond primarily by altering the sky condition of

  14. Characterizing Sky Spectra Using SDSS BOSS Data

    Science.gov (United States)

    Florez, Lina Maria; Strauss, Michael A.

    2018-01-01

    In the optical/near-infrared spectra gathered by a ground-based telescope observing very faint sources, the strengths of the emission lines due to the Earth’s atmosphere can be many times larger than the fluxes of the sources we are interested in. Thus the limiting factor in faint-object spectroscopy is the degree to which systematics in the sky subtraction can be minimized. Longwards of 6000 Angstroms, the night-sky spectrum is dominated by multiple vibrational/rotational transitions of the OH radical from our upper atmosphere. While the wavelengths of these lines are the same in each sky spectrum, their relative strengths vary considerably as a function of time and position on the sky. The better we can model their strengths, the better we can hope to subtract them off. We expect that the strength of lines from common upper energy levels will be correlated with one another. We used flux-calibrated sky spectra from the Sloan Digital Sky Survey Baryon Oscillation Spectroscopic Survey (SDSS BOSS) to explore these correlations. Our aim is to use these correlations for creating improved sky subtraction algorithms for the Prime Focus Spectrograph (PFS) on the 8.2-meter Subaru Telescope. When PFS starts gathering data in 2019, it will be the most powerful multi-object spectrograph in the world. Since PFS will be gathering data on sources as faint as 24th magnitude and fainter, it's of upmost importance to be able to accurately measure and subtract sky spectra from the data that we receive.

  15. One year of downwelling spectral radiance measurements from 100 to 1400 cm-1 at Dome Concordia: Results in clear conditions

    Science.gov (United States)

    Rizzi, R.; Arosio, C.; Maestri, T.; Palchetti, L.; Bianchini, G.; Del Guasta, M.

    2016-09-01

    The present work examines downwelling radiance spectra measured at the ground during 2013 by a Far Infrared Fourier Transform Spectrometer at Dome C, Antarctica. A tropospheric backscatter and depolarization lidar is also deployed at same site, and a radiosonde system is routinely operative. The measurements allow characterization of the water vapor and clouds infrared properties in Antarctica under all sky conditions. In this paper we specifically discuss cloud detection and the analysis in clear sky condition, required for the discussion of the results obtained in cloudy conditions. First, the paper discusses the procedures adopted for the quality control of spectra acquired automatically. Then it describes the classification procedure used to discriminate spectra measured in clear sky from cloudy conditions. Finally a selection is performed and 66 clear cases, spanning the whole year, are compared to simulations. The computation of layer molecular optical depth is performed with line-by-line techniques and a convolution to simulate the Radiation Explorer in the Far InfraRed-Prototype for Applications and Development (REFIR-PAD) measurements; the downwelling radiance for selected clear cases is computed with a state-of-the-art adding-doubling code. The mean difference over all selected cases between simulated and measured radiance is within experimental error for all the selected microwindows except for the negative residuals found for all microwindows in the range 200 to 400 cm-1, with largest values around 295.1 cm-1. The paper discusses possible reasons for the discrepancy and identifies the incorrect magnitude of the water vapor total absorption coefficient as the cause of such large negative radiance bias below 400 cm-1.

  16. Navigation by light polarization in clear and turbid waters

    Science.gov (United States)

    Lerner, Amit; Sabbah, Shai; Erlick, Carynelisa; Shashar, Nadav

    2011-01-01

    Certain terrestrial animals use sky polarization for navigation. Certain aquatic species have also been shown to orient according to a polarization stimulus, but the correlation between underwater polarization and Sun position and hence the ability to use underwater polarization as a compass for navigation is still under debate. To examine this issue, we use theoretical equations for per cent polarization and electric vector (e-vector) orientation that account for the position of the Sun, refraction at the air–water interface and Rayleigh single scattering. The polarization patterns predicted by these theoretical equations are compared with measurements conducted in clear and semi-turbid coastal sea waters at 2 m and 5 m depth over sea floors of 6 m and 28 m depth. We find that the per cent polarization is correlated with the Sun's elevation only in clear waters. We furthermore find that the maximum value of the e-vector orientation angle equals the angle of refraction only in clear waters, in the horizontal viewing direction, over the deeper sea floor. We conclude that navigation by use of underwater polarization is possible under restricted conditions, i.e. in clear waters, primarily near the horizontal viewing direction, and in locations where the sea floor has limited effects on the light's polarization. PMID:21282170

  17. SkyProbeBV: dual-color absolute sky transparency monitor to optimize science operations

    Science.gov (United States)

    Cuillandre, Jean-Charles; Magnier, Eugene; Sabin, Dan; Mahoney, Billy

    2008-07-01

    Mauna Kea (4200 m elevation, Hawaii) is known for its pristine seeing conditions, but sky transparency can be an issue for science operations: 25% of the nights are not photometric, a cloud coverage mostly due to high-altitude thin cirrus. The Canada-France-Hawaii Telescope (CFHT) is upgrading its real-time sky transparency monitor in the optical domain (V-band) into a dual-color system by adding a B-band channel and redesigning the entire optical and mechanical assembly. Since 2000, the original single-channel SkyProbe has gathered one exposure every minute during each observing night using a small CCD camera with a very wide field of view (35 sq. deg.) encompassing the region pointed by the telescope for science operations, and exposures long enough (30 seconds) to capture at least 100 stars of Hipparcos' Tychos catalog at high galactic latitudes (and up to 600 stars at low galactic latitudes). A key advantage of SkyProbe over direct thermal infrared imaging detection of clouds, is that it allows an accurate absolute measurement, within 5%, of the true atmospheric absorption by clouds affecting the data being gathered by the telescope's main science instrument. This system has proven crucial for decision making in the CFHT queued service observing (QSO), representing today 95% of the telescope time: science exposures taken in non-photometric conditions are automatically registered for being re-observed later on (at 1/10th of the original exposure time per pointing in the observed filters) to ensure a proper final absolute photometric calibration. If the absorption is too high, exposures can be repeated, or the observing can be done for a lower ranked science program. The new dual color system (simultaneous B & V bands) will allow a better characterization of the sky properties above Mauna Kea and should enable a better detection of the thinner cirrus (absorption down to 0.02 mag., i.e. 2%). SkyProbe is operated within the Elixir pipeline, a collection of tools

  18. Using routine meteorological data to derive sky conditions

    Directory of Open Access Journals (Sweden)

    D. Pagès

    2003-03-01

    Full Text Available Sky condition is a matter of interest for public and weather predictors as part of weather analyses. In this study, we apply a method that uses total solar radiation and other meteorological data recorded by an automatic station for deriving an estimation of the sky condition. The impetus of this work is the intention of the Catalan Meteorological Service (SMC to provide the public with real-time information about the sky condition. The methodology for deriving sky conditions from meteorological records is based on a supervised classification technique called maximum likelihood method. In this technique we first need to define features which are derived from measured variables. Second, we must decide which sky conditions are intended to be distinguished. Some analyses have led us to use four sky conditions: (a cloudless or almost cloudless sky, (b scattered clouds, (c mostly cloudy – high clouds, (d overcast – low clouds. An additional case, which may be treated separately, corresponds to precipitation (rain or snow. The main features for estimating sky conditions are, as expected, solar radiation and its temporal variability. The accuracy of this method of guessing sky conditions compared with human observations is around 70% when applied to four sites in Catalonia (NE Iberian Peninsula. The agreement increases if we take into account the uncertainty both in the automatic classifier and in visual observations.Key words. Meteorological and atmospheric dynamics (instruments and techniques; radiative processes – Atmospheric composition and structure (cloud physics and chemistry

  19. Algolcam: Low Cost Sky Scanning with Modern Technology

    Science.gov (United States)

    Connors, Martin; Bolton, Dempsey; Doktor, Ian

    2016-01-01

    Low cost DSLR cameras running under computer control offer good sensitivity, high resolution, small size, and the convenience of digital image handling. Recent developments in small single board computers have pushed the performance to cost and size ratio to unprecedented values, with the further advantage of very low power consumption. Yet a third technological development is motor control electronics which is easily integrated with the computer to make an automated mount, which in our case is custom built, but with similar mounts available commercially. Testing of such a system under a clear plastic dome at our auroral observatory was so successful that we have developed a weatherproof housing allowing use during the long, cold, and clear winter nights at northerly latitudes in Canada. The main advantage of this housing should be improved image quality as compared to operation through clear plastic. We have improved the driving software to include the ability to self-calibrate pointing through the web API of astrometry.net, and data can be reduced automatically through command line use of the Muniwin program. The mount offers slew in declination and RA, and tracking at sidereal or other rates in RA. Our previous tests with a Nikon D5100 with standard lenses in the focal length range 50-200 mm, operating at f/4 to f/5, allowed detection of 12th magnitude stars with 30 second exposure under very dark skies. At 85 mm focal length, a field of 15° by 10° is imaged with 4928 by 3264 color pixels, and we have adopted an 85 mm fixed focal length f/1.4 lens (as used by Project Panoptes), which we expect will give a limited magnitude approaching 15. With a large field of view, deep limiting magnitude, low cost, and ease of construction and use, we feel that the Algolcam offers great possibilities in monitoring and finding changes in the sky. We have already applied it to variable star light curves, and with a suitable pipeline for detection of moving or varying objects

  20. The Python Sky Model: software for simulating the Galactic microwave sky

    Science.gov (United States)

    Thorne, B.; Dunkley, J.; Alonso, D.; Næss, S.

    2017-08-01

    We present a numerical code to simulate maps of Galactic emission in intensity and polarization at microwave frequencies, aiding in the design of cosmic microwave background experiments. This python code builds on existing efforts to simulate the sky by providing an easy-to-use interface and is based on publicly available data from the WMAP (Wilkinson Microwave Anisotropy Probe) and Planck satellite missions. We simulate synchrotron, thermal dust, free-free and anomalous microwave emission over the whole sky, in addition to the cosmic microwave background, and include a set of alternative prescriptions for the frequency dependence of each component, for example, polarized dust with multiple temperatures and a decorrelation of the signals with frequency, which introduce complexity that is consistent with current data. We also present a new prescription for adding small-scale realizations of these components at resolutions greater than current all-sky measurements. The usefulness of the code is demonstrated by forecasting the impact of varying foreground complexity on the recovered tensor-to-scalar ratio for the LiteBIRD satellite. The code is available at: https://github.com/bthorne93/PySM_public.

  1. Dark Skies: Local Success, Global Challenge

    Science.gov (United States)

    Lockwood, G. W.

    2009-01-01

    The Flagstaff, Arizona 1987 lighting code reduced the growth rate of man-made sky glow by a third. Components of the code include requirements for full cutoff lighting, lumens per acre limits in radial zones around observatories, and use of low-pressure sodium monochromatic lighting for roadways and parking lots. Broad public acceptance of Flagstaff's lighting code demonstrates that dark sky preservation has significant appeal and few visibility or public safety negatives. An inventory by C. Luginbuhl et al. of the light output and shielding of a sampling of various zoning categories (municipal, commercial, apartments, single-family residences, roadways, sports facilities, industrial, etc.), extrapolated over the entire city, yields a total output of 139 million lumens. Commercial and industrial sources account for 62% of the total. Outdoor sports lighting increases the total by 24% on summer evenings. Flagstaff's per capita lumen output is 2.5 times greater than the nominal 1,000 lumens per capita assumed by R. Garstang in his early sky glow modeling work. We resolved the discrepancy with respect to Flagstaff's measured sky glow using an improved model that includes substantial near ground attenuation by foliage and structures. A 2008 university study shows that astronomy contributes $250M annually to Arizona's economy. Another study showed that the application of lighting codes throughout Arizona could reduce energy consumption significantly. An ongoing effort led by observatory directors statewide will encourage lighting controls in currently unregulated metropolitan areas whose growing sky glow threatens observatory facilities more than 100 miles away. The national press (New York Times, the New Yorker, the Economist, USA Today, etc.) have publicized dark sky issues but frequent repetition of the essential message and vigorous action will be required to steer society toward darker skies and less egregious waste.

  2. A-Train Aerosol Observations Preliminary Comparisons with AeroCom Models and Pathways to Observationally Based All-Sky Estimates

    Science.gov (United States)

    Redemann, J.; Livingston, J.; Shinozuka, Y.; Kacenelenbogen, M.; Russell, P.; LeBlanc, S.; Vaughan, M.; Ferrare, R.; Hostetler, C.; Rogers, R.; hide

    2014-01-01

    We have developed a technique for combining CALIOP aerosol backscatter, MODIS spectral AOD (aerosol optical depth), and OMI AAOD (absorption aerosol optical depth) retrievals for the purpose of estimating full spectral sets of aerosol radiative properties, and ultimately for calculating the 3-D distribution of direct aerosol radiative forcing. We present results using one year of data collected in 2007 and show comparisons of the aerosol radiative property estimates to collocated AERONET retrievals. Use of the recently released MODIS Collection 6 data for aerosol optical depths derived with the dark target and deep blue algorithms has extended the coverage of the multi-sensor estimates towards higher latitudes. We compare the spatio-temporal distribution of our multi-sensor aerosol retrievals and calculations of seasonal clear-sky aerosol radiative forcing based on the aerosol retrievals to values derived from four models that participated in the latest AeroCom model intercomparison initiative. We find significant inter-model differences, in particular for the aerosol single scattering albedo, which can be evaluated using the multi-sensor A-Train retrievals. We discuss the major challenges that exist in extending our clear-sky results to all-sky conditions. On the basis of comparisons to suborbital measurements, we present some of the limitations of the MODIS and CALIOP retrievals in the presence of adjacent or underlying clouds. Strategies for meeting these challenges are discussed.

  3. Teach and Touch the Earth and Sky

    Science.gov (United States)

    Florina Tendea, Camelia

    2017-04-01

    supplemented attitudes and behaviors that care for their health, for the health of others and to the natural environment, interest and appreciation of logical argument; curiosity and concern about environmental phenomena, independent thinking, creativity. I think that is very important, like teacher, to combine the two parts of teaching: theoretical one and practical one. TEACH means setting a bag of theoretical aspects and also who can provide us support?(ideas, resources, scientific competitions etc.) and TOUCH means practical aspects for teachers & students. Resoults: Participating of teachers and students at workshops, round table, scientific debates provide knowledge about Space in context of STEM disciplines, Hands-on experiences; Find different situations of learning; Ideas, methods and techniques for design new lessons; Real scientific data from ESA/ESERO/ROSA sites; Chance to be part of international projects. Conclusions:Teach and Touch the Earth and Sky - could be a great chance to benefit from the proposed programs of ESA, through which space can be brought into the classroom and used as a tool for teaching and learning, moreover access to actual scientific data and experiences shared by the scientists, or other specialists offers a new prespective in the study of STEM subjects by students.

  4. Moessbauer study of the firing process of the imitative ancient sky-blue Jun porcelain

    International Nuclear Information System (INIS)

    Gao Zhengyao; Chen Xiande

    1994-01-01

    Moessbauer spectra of the imitative ancient Jun porcelain indicate that the glaze and body materials contain Fe 2 O 3 , Fe 3 O 4 and structural iron. It is clear that during the firing process, the glaze undergoes dehydration, dehydroxylation, vitrification and recrystallization. The Fe 2+ quadrupole splitting value of the paramagnetic peak of the body material is high even at low firing temperatures. For the body material, the distinction between dehydration and dehydroxylation is not clear. The changes of magnetism of the glaze and body materials in the firing process and the coloring mechanism of the sky-blue Jun porcelain are analyzed in the present paper. (orig.)

  5. Using routine meteorological data to derive sky conditions

    Directory of Open Access Journals (Sweden)

    D. Pagès

    Full Text Available Sky condition is a matter of interest for public and weather predictors as part of weather analyses. In this study, we apply a method that uses total solar radiation and other meteorological data recorded by an automatic station for deriving an estimation of the sky condition. The impetus of this work is the intention of the Catalan Meteorological Service (SMC to provide the public with real-time information about the sky condition. The methodology for deriving sky conditions from meteorological records is based on a supervised classification technique called maximum likelihood method. In this technique we first need to define features which are derived from measured variables. Second, we must decide which sky conditions are intended to be distinguished. Some analyses have led us to use four sky conditions: (a cloudless or almost cloudless sky, (b scattered clouds, (c mostly cloudy – high clouds, (d overcast – low clouds. An additional case, which may be treated separately, corresponds to precipitation (rain or snow. The main features for estimating sky conditions are, as expected, solar radiation and its temporal variability. The accuracy of this method of guessing sky conditions compared with human observations is around 70% when applied to four sites in Catalonia (NE Iberian Peninsula. The agreement increases if we take into account the uncertainty both in the automatic classifier and in visual observations.

    Key words. Meteorological and atmospheric dynamics (instruments and techniques; radiative processes – Atmospheric composition and structure (cloud physics and chemistry

  6. Sky light polarization detection with linear polarizer triplet in light field camera inspired by insect vision.

    Science.gov (United States)

    Zhang, Wenjing; Cao, Yu; Zhang, Xuanzhe; Liu, Zejin

    2015-10-20

    Stable information of a sky light polarization pattern can be used for navigation with various advantages such as better performance of anti-interference, no "error cumulative effect," and so on. But the existing method of sky light polarization measurement is weak in real-time performance or with a complex system. Inspired by the navigational capability of a Cataglyphis with its compound eyes, we introduce a new approach to acquire the all-sky image under different polarization directions with one camera and without a rotating polarizer, so as to detect the polarization pattern across the full sky in a single snapshot. Our system is based on a handheld light field camera with a wide-angle lens and a triplet linear polarizer placed over its aperture stop. Experimental results agree with the theoretical predictions. Not only real-time detection but simple and costless architecture demonstrates the superiority of the approach proposed in this paper.

  7. Gaia , an all sky astrometric and photometric survey

    International Nuclear Information System (INIS)

    Carrasco, J.M.

    2017-01-01

    Gaia space mission includes a low resolution spectroscopic instrument to classify and parametrize the observed sources. Gaia is a full-sky unbiased survey down to about 20th magnitude. The scanning law yields a rather uniform coverage of the sky over the full mission. The data reduction is a global one over the full mission. Both sky coverage and data reduction strategy ensure an unprecedented all-sky homogeneous spectrophotometric survey. Certainly, that survey is of interest for future on-ground and space projects (LSST, PLATO, EUCLID, ...). This work addresses the exploitation of the Gaia spectrophotometry as standard photometry reference through the discussion of the sky coverage, the spectrophotometric precision and the expected uncertainties of the synthetic photometry derived from the low resolution Gaia spectra and photometry.

  8. Night time cooling by ventilation or night sky radiation combined with in-room radiant cooling panels including phase change materials

    DEFF Research Database (Denmark)

    Bourdakis, Eleftherios; Olesen, Bjarne W.; Grossule, Fabio

    Night sky radiative cooling technology using PhotoVoltaic/Thermal panels (PVT) and night time ventilation have been studied both by means of simulations and experiments to evaluate their potential and to validate the created simulation model used to describe it. An experimental setup has been...... depending on the sky clearness. This cooling power was enough to remove the stored heat and regenerate the ceiling panels. The validation simulation model results related to PCM were close to the corresponding results extracted from the experiment, while the results related to the production of cold water...... through the night sky radiative cooling differed significantly. The possibility of night time ventilation was studied through simulations for three different latitudes. It was concluded that for Danish climatic conditions night time ventilation would also be able to regenerate the panels while its...

  9. Design of a multiband near-infrared sky brightness monitor using an InSb detector.

    Science.gov (United States)

    Dong, Shu-Cheng; Wang, Jian; Tang, Qi-Jie; Jiang, Feng-Xin; Chen, Jin-Ting; Zhang, Yi-Hao; Wang, Zhi-Yue; Chen, Jie; Zhang, Hong-Fei; Jiang, Hai-Jiao; Zhu, Qing-Feng; Jiang, Peng; Ji, Tuo

    2018-02-01

    Infrared sky background level is an important parameter of infrared astronomy observations from the ground, particularly for a candidate site of an infrared capable observatory since low background level is required for such a site. The Chinese astronomical community is looking for a suitable site for a future 12 m telescope, which is designed for working in both optical and infrared wavelengths. However, none of the proposed sites has been tested for infrared observations. Nevertheless, infrared sky background measurements are also important during the design of infrared observing instruments. Based on the requirement, in order to supplement the current site survey data and guide the design of future infrared instruments, a multiband near-infrared sky brightness monitor (MNISBM) based on an InSb sensor is designed in this paper. The MNISBM consists of an optical system, mechanical structure and control system, detector and cooler, high gain readout electronics, and operational software. It is completed and tested in the laboratory. The results show that the sensitivity of the MNISBM meets the requirements of the measurement of near-infrared sky background level of several well-known astronomical infrared observing sites.

  10. Design of a multiband near-infrared sky brightness monitor using an InSb detector

    Science.gov (United States)

    Dong, Shu-cheng; Wang, Jian; Tang, Qi-jie; Jiang, Feng-xin; Chen, Jin-ting; Zhang, Yi-hao; Wang, Zhi-yue; Chen, Jie; Zhang, Hong-fei; Jiang, Hai-jiao; Zhu, Qing-feng; Jiang, Peng; Ji, Tuo

    2018-02-01

    Infrared sky background level is an important parameter of infrared astronomy observations from the ground, particularly for a candidate site of an infrared capable observatory since low background level is required for such a site. The Chinese astronomical community is looking for a suitable site for a future 12 m telescope, which is designed for working in both optical and infrared wavelengths. However, none of the proposed sites has been tested for infrared observations. Nevertheless, infrared sky background measurements are also important during the design of infrared observing instruments. Based on the requirement, in order to supplement the current site survey data and guide the design of future infrared instruments, a multiband near-infrared sky brightness monitor (MNISBM) based on an InSb sensor is designed in this paper. The MNISBM consists of an optical system, mechanical structure and control system, detector and cooler, high gain readout electronics, and operational software. It is completed and tested in the laboratory. The results show that the sensitivity of the MNISBM meets the requirements of the measurement of near-infrared sky background level of several well-known astronomical infrared observing sites.

  11. Examining Dense Data Usage near the Regions with Severe Storms in All-Sky Microwave Radiance Data Assimilation and Impacts on GEOS Hurricane Analyses

    Science.gov (United States)

    Kim, Min-Jeong; Jin, Jianjun; McCarty, Will; El Akkraoui, Amal; Todling, Ricardo; Gelaro, Ron

    2018-01-01

    Many numerical weather prediction (NWP) centers assimilate radiances affected by clouds and precipitation from microwave sensors, with the expectation that these data can provide critical constraints on meteorological parameters in dynamically sensitive regions to make significant impacts on forecast accuracy for precipitation. The Global Modeling and Assimilation Office (GMAO) at NASA Goddard Space Flight Center assimilates all-sky microwave radiance data from various microwave sensors such as all-sky GPM Microwave Imager (GMI) radiance in the Goddard Earth Observing System (GEOS) atmospheric data assimilation system (ADAS), which includes the GEOS atmospheric model, the Gridpoint Statistical Interpolation (GSI) atmospheric analysis system, and the Goddard Aerosol Assimilation System (GAAS). So far, most of NWP centers apply same large data thinning distances, that are used in clear-sky radiance data to avoid correlated observation errors, to all-sky microwave radiance data. For example, NASA GMAO is applying 145 km thinning distances for most of satellite radiance data including microwave radiance data in which all-sky approach is implemented. Even with these coarse observation data usage in all-sky assimilation approach, noticeable positive impacts from all-sky microwave data on hurricane track forecasts were identified in GEOS-5 system. The motivation of this study is based on the dynamic thinning distance method developed in our all-sky framework to use of denser data in cloudy and precipitating regions due to relatively small spatial correlations of observation errors. To investigate the benefits of all-sky microwave radiance on hurricane forecasts, several hurricane cases selected between 2016-2017 are examined. The dynamic thinning distance method is utilized in our all-sky approach to understand the sources and mechanisms to explain the benefits of all-sky microwave radiance data from various microwave radiance sensors like Advanced Microwave Sounder Unit

  12. The Sky at Night

    CERN Document Server

    Moore, Patrick

    2010-01-01

    For more than 50 years now Sir Patrick Moore has presented the BBC Television series Sky at Night; not a month has been missed – a record for any television series, and a record which may never be broken. Every three years or so a book is published covering the main events in both astronomy and space research. This is the 13th volume, not only a record of the programmes but also of the great advances and discoveries during the period covered - eclipses, comets, and the strange chemical lakes of Titan, for instance, but also anniversaries such as the fifteenth “birthday” of the Hubble Space Telescope, and not forgetting the programme celebrating the Sky at Night’s 50th year, attended by astronaut Piers Sellars and many others who appeared on the programme over the years. All the chapters are self-contained, and fully illustrated. In this new Sky at Night book you will find much to entertain you. It will appeal to amateurs and professionals alike.

  13. Spatiotemporal change of sky polarization during the total solar eclipse on 29 March 2006 in Turkey: polarization patterns of the eclipsed sky observed by full-sky imaging polarimetry.

    Science.gov (United States)

    Sipocz, Brigitta; Hegedüs, Ramón; Kriska, György; Horváth, Gábor

    2008-12-01

    Using 180 degrees field-of-view (full-sky) imaging polarimetry, we measured the spatiotemporal change of the polarization of skylight during the total solar eclipse on 29 March 2006 in Turkey. We present our observations here on the temporal variation of the celestial patterns of the degree p and angle alpha of linear polarization of the eclipsed sky measured in the red (650 nm), green (550 nm), and blue (450 nm) parts of the spectrum. We also report on the temporal and spectral change of the positions of neutral (unpolarized, p = 0) points, and points with local minima or maxima of p of the eclipsed sky. Our results are compared with the observations performed by the same polarimetric technique during the total solar eclipse on 11 August 1999 in Hungary. Practically the same characteristics of celestial polarization were encountered during both eclipses. This shows that the observed polarization phenomena of the eclipsed sky may be general.

  14. Correcting the relationship between PRI and shadow fraction for the blue sky effect

    Science.gov (United States)

    Mõttus, Matti

    2016-04-01

    The Photochemical Reflectance Index (PRI) is defined as the normalized difference ratio of leaf reflectance at two specific wavelengths in the green spectral region. Its value depends on the status of leaf carotenoid content, and especially that of the xanthophyll cycle pigments. Due to the dependence on the xanthophyll cycle, when the photosynthetic apparatus of green leaves is close to the saturation limit, their PRI becomes dependent on light conditions. Therefore, by measuring the PRI of leaves in the same canopy under different local irradiance conditions on a sunny day, it should be possible to determine the saturation level of the leaves. In turn, this gives information on the light use efficiency (LUE) of the vegetation canopy. The average light conditions of visible foliage elements are often quantified with the shadow fraction -- the fraction of visible foliage not lit by direct sunlight. The dependence of PRI on the shadow fraction has been used to remotely measure canopy LUE on clear days. Variations in shadow fraction have been achieved with multiangular measurement. However, besides photosynthetic downregulation, the dependence of canopy PRI on shadow fraction is affected by the blue sky radiation caused by scattering in the atmosphere. To quantify this effect on remotely sensed PRI, we present the underlying definitions relating leaf and canopy PRI and perform the required calculations for typical midsummer conditions in Central Finland. We demonstrate that the effect of blue sky radiation on the variation of PRI with canopy shadow fraction is similar in shape and magnitude to that of LUE variations reported in literature. Next, we propose a new method to assess these PRI variations in structured vegetation. We investiagate this blue sky effect on the PRI -- shadow fraction relationship with high spatial (60 cm) and spectral (9.8 nm) resolution airborne imaging spectroscopy data from Hyytiälä, Finland. We evaluate the spectral irradiance in

  15. Experience in Solar System and Sky Motions

    Science.gov (United States)

    Coles, K. S.

    2017-12-01

    To help students predict where they will see objects in the sky, they must comprehend sky motion and the relative motions of individual objects. Activities to promote this comprehension among college and secondary students include: Tracking star motion in the planetarium: Students predict star motion by marking the expected path on plastic hemisphere models of the celestial dome. They check their prediction by observing and marking the actual motion. For comprehension, comparing motion in different parts of the sky surpasses two-dimensional views of the sky in books or on computers. Mastery is assessed by the same exercise with the sky set at other latitudes, including those on the other side of the equator. Making sundials: Students first make a horizontal sundial for the latitude of their choice following written directions (e.g., Waugh, 1973). One problem to solve is how to convert sundial time to standard time. A prompt is a picture of the analemma (the position of the Sun in the sky at a fixed clock time over the course of a year). Tests of mastery include the questions, "What accounts for the shape of the analemma?" and "What information is needed to predict the shape of the analemma one would see on other planets?" Reference: Waugh, A. E., 1973, Sundials: their theory and construction: Dover, 228 p.

  16. 2015 Australasian sky guide

    CERN Document Server

    Lomb, Nick

    2014-01-01

    Compact, easy to use and reliable, this popular guide has been providing star gazers with everything they need to know about the southern night sky for the past 25 years. The 2015 guide will celebrate this landmark with highlights from the past as well as monthly astronomy maps, viewing tips and highlights, and details of the year's exciting celestial events.Wherever you are in Australia or New Zealand, easy calculations allow you to estimate local rise and set times for the Sun, Moon and planets. The 2015 Australasian Sky Guide also provides information on the solar system, updated with the l

  17. 2013 Australasian sky guide

    CERN Document Server

    Lomb, Nick

    2012-01-01

    Compact, easy to use and reliable, this popular guide contains everything you need to know about the southern night sky with monthly star maps, diagrams and details of all the year's exciting celestial events. Wherever you are in Australia or New Zealand, easy calculations allow you to determine when the Sun, Moon and planets will rise and set throughout the year. Also included is information on the latest astronomical findings from space probes and telescopes around the world. The Sky guide has been published annually by the Powerhouse Museum, Sydney, since 1991. It is recommended for photogr

  18. Evaluating the spatio-temporal performance of sky-imager-based solar irradiance analysis and forecasts

    Science.gov (United States)

    Schmidt, Thomas; Kalisch, John; Lorenz, Elke; Heinemann, Detlev

    2016-03-01

    Clouds are the dominant source of small-scale variability in surface solar radiation and uncertainty in its prediction. However, the increasing share of solar energy in the worldwide electric power supply increases the need for accurate solar radiation forecasts. In this work, we present results of a very short term global horizontal irradiance (GHI) forecast experiment based on hemispheric sky images. A 2-month data set with images from one sky imager and high-resolution GHI measurements from 99 pyranometers distributed over 10 km by 12 km is used for validation. We developed a multi-step model and processed GHI forecasts up to 25 min with an update interval of 15 s. A cloud type classification is used to separate the time series into different cloud scenarios. Overall, the sky-imager-based forecasts do not outperform the reference persistence forecasts. Nevertheless, we find that analysis and forecast performance depends strongly on the predominant cloud conditions. Especially convective type clouds lead to high temporal and spatial GHI variability. For cumulus cloud conditions, the analysis error is found to be lower than that introduced by a single pyranometer if it is used representatively for the whole area in distances from the camera larger than 1-2 km. Moreover, forecast skill is much higher for these conditions compared to overcast or clear sky situations causing low GHI variability, which is easier to predict by persistence. In order to generalize the cloud-induced forecast error, we identify a variability threshold indicating conditions with positive forecast skill.

  19. Evaluating the spatio-temporal performance of sky-imager-based solar irradiance analysis and forecasts

    Directory of Open Access Journals (Sweden)

    T. Schmidt

    2016-03-01

    Full Text Available Clouds are the dominant source of small-scale variability in surface solar radiation and uncertainty in its prediction. However, the increasing share of solar energy in the worldwide electric power supply increases the need for accurate solar radiation forecasts. In this work, we present results of a very short term global horizontal irradiance (GHI forecast experiment based on hemispheric sky images. A 2-month data set with images from one sky imager and high-resolution GHI measurements from 99 pyranometers distributed over 10 km by 12 km is used for validation. We developed a multi-step model and processed GHI forecasts up to 25 min with an update interval of 15 s. A cloud type classification is used to separate the time series into different cloud scenarios. Overall, the sky-imager-based forecasts do not outperform the reference persistence forecasts. Nevertheless, we find that analysis and forecast performance depends strongly on the predominant cloud conditions. Especially convective type clouds lead to high temporal and spatial GHI variability. For cumulus cloud conditions, the analysis error is found to be lower than that introduced by a single pyranometer if it is used representatively for the whole area in distances from the camera larger than 1–2 km. Moreover, forecast skill is much higher for these conditions compared to overcast or clear sky situations causing low GHI variability, which is easier to predict by persistence. In order to generalize the cloud-induced forecast error, we identify a variability threshold indicating conditions with positive forecast skill.

  20. Evaluating the spatio-temporal performance of sky imager based solar irradiance analysis and forecasts

    Science.gov (United States)

    Schmidt, T.; Kalisch, J.; Lorenz, E.; Heinemann, D.

    2015-10-01

    Clouds are the dominant source of variability in surface solar radiation and uncertainty in its prediction. However, the increasing share of solar energy in the world-wide electric power supply increases the need for accurate solar radiation forecasts. In this work, we present results of a shortest-term global horizontal irradiance (GHI) forecast experiment based on hemispheric sky images. A two month dataset with images from one sky imager and high resolutive GHI measurements from 99 pyranometers distributed over 10 km by 12 km is used for validation. We developed a multi-step model and processed GHI forecasts up to 25 min with an update interval of 15 s. A cloud type classification is used to separate the time series in different cloud scenarios. Overall, the sky imager based forecasts do not outperform the reference persistence forecasts. Nevertheless, we find that analysis and forecast performance depend strongly on the predominant cloud conditions. Especially convective type clouds lead to high temporal and spatial GHI variability. For cumulus cloud conditions, the analysis error is found to be lower than that introduced by a single pyranometer if it is used representatively for the whole area in distances from the camera larger than 1-2 km. Moreover, forecast skill is much higher for these conditions compared to overcast or clear sky situations causing low GHI variability which is easier to predict by persistence. In order to generalize the cloud-induced forecast error, we identify a variability threshold indicating conditions with positive forecast skill.

  1. Aquarius L-Band Radiometers Calibration Using Cold Sky Observations

    Science.gov (United States)

    Dinnat, Emmanuel P.; Le Vine, David M.; Piepmeier, Jeffrey R.; Brown, Shannon T.; Hong, Liang

    2015-01-01

    An important element in the calibration plan for the Aquarius radiometers is to look at the cold sky. This involves rotating the satellite 180 degrees from its nominal Earth viewing configuration to point the main beams at the celestial sky. At L-band, the cold sky provides a stable, well-characterized scene to be used as a calibration reference. This paper describes the cold sky calibration for Aquarius and how it is used as part of the absolute calibration. Cold sky observations helped establish the radiometer bias, by correcting for an error in the spillover lobe of the antenna pattern, and monitor the long-term radiometer drift.

  2. Polarization patterns of the twilight sky

    Science.gov (United States)

    Cronin, Thomas W.; Warrant, Eric J.; Greiner, Birgit

    2005-08-01

    Although natural light sources produce depolarized light, patterns of partially linearly polarized light appear in the sky due to scattering from air molecules, dust, and aerosols. Many animals, including bees and ants, orient themselves to patterns of polarization that are present in daytime skies, when the intensity is high and skylight polarization is strong and predictable. The halicitid bee Megalopta genalis inhabits rainforests in Central America. Unlike typical bees, it forages before sunrise and after sunset, when light intensities under the forest canopy are very low, and must find its way to food sources and return to its nest in visually challenging circumstances. An important cue for the orientation could be patterns of polarization in the twilight sky. Therefore, we used a calibrated digital camera to image skylight polarization in an overhead patch of sky, 87.6° across, before dawn on Barro Colorado Island in Panama, where the bees are found. We simultaneously measured the spectral properties of polarized light in a cloudless patch of sky 15° across centered on the zenith. We also performed full-sky imaging of polarization before dawn and after dusk on Lizard Island in Australia, another tropical island. During twilight, celestial polarized light occurs in a wide band stretching perpendicular to the location of the hidden sun and reaching typical degrees of polarization near 80% at wavelengths >600 nm. This pattern appears about 45 minutes before local sunrise or disappears 45 minutes after local sunset (about 20 minutes after the onset of astronomical twilight at dawn, or before its end at dusk) and extends with little change through the entire twilight period. Such a strong and reliable orientation cue could be used for flight orientation by any animal with polarization sensitivity that navigates during twilight.

  3. Go-To Telescopes Under Suburban Skies

    CERN Document Server

    Monks, Neale

    2010-01-01

    For the last four centuries stargazers have turned their telescopes to the night skies to look at its wonders, but only in this age of computers has it become possible to let the telescope find for you the object you are looking for! So-called “go-to” telescopes are programmed with the locations of thousands of objects, including dazzling distant Suns, stunning neighboring galaxies, globular and open star clusters, the remnants of past supernovae, and many other breathtaking sights. This book does not tell you how to use your Go-to telescope. Your manual will help you do that. It tells you what to look for in the deep sky and why, and what equipment to best see it with. Organized broadly by what is best for viewing in the northern hemisphere in different seasons, Monks further divides the sights of each season into groupings such as “Showpiece Objects,” “Interesting Deep Sky Objects,” and “Obscure and Challenging Deep Sky Objects.” He also tells what objects are visible even in light-polluted ...

  4. SKYMONITOR: A Global Network for Sky Brightness Measurements

    Science.gov (United States)

    Davis, Donald R.; Mckenna, D.; Pulvermacher, R.; Everett, M.

    2010-01-01

    We are implementing a global network to measure sky brightness at dark-sky critical sites with the goal of creating a multi-decade database. The heart of this project is the Night Sky Brightness Monitor (NSBM), an autonomous 2 channel photometer which measures night sky brightness in the visual wavelengths (Mckenna et al, AAS 2009). Sky brightness is measured every minute at two elevation angles typically zenith and 20 degrees to monitor brightness and transparency. The NSBM consists of two parts, a remote unit and a base station with an internet connection. Currently these devices use 2.4 Ghz transceivers with a range of 100 meters. The remote unit is battery powered with daytime recharging using a solar panel. Data received by the base unit is transmitted via email protocol to IDA offices in Tucson where it will be collected, archived and made available to the user community via a web interface. Two other versions of the NSBM are under development: one for radio sensitive areas using an optical fiber link and the second that reads data directly to a laptop for sites without internet access. NSBM units are currently undergoing field testing at two observatories. With support from the National Science Foundation, we will construct and install a total of 10 units at astronomical observatories. With additional funding, we will locate additional units at other sites such as National Parks, dark-sky preserves and other sites where dark sky preservation is crucial. We will present the current comparison with the National Park Service sky monitoring camera. We anticipate that the SKYMONITOR network will be functioning by the end of 2010.

  5. An Innovative Collaboration on Dark Skies Education

    Science.gov (United States)

    Walker, Constance E.; Mayer, M.; EPO Students, NOAO

    2011-01-01

    Dark night skies are being lost all over the globe, and hundreds of millions of dollars of energy are being wasted in the process.. Improper lighting is the main cause of light pollution. Light pollution is a concern on many fronts, affecting safety, energy conservation, cost, human health, and wildlife. It also robs us of the beauty of viewing the night sky. In the U.S. alone, over half of the population cannot see the Milky Way from where they live. To help address this, the National Optical Astronomy Observatory Education and Public Outreach (NOAO EPO) staff created two programs: Dark Skies Rangers and GLOBE at Night. Through the two programs, students learn about the importance of dark skies and experience activities that illustrate proper lighting, light pollution's effects on wildlife and how to measure the darkness of their skies. To disseminate the programs locally in an appropriate yet innovative venue, NOAO partnered with the Cooper Center for Environmental Learning in Tucson, Arizona. Operated by the largest school district in Tucson and the University of Arizona College of Education, the Cooper Center educates thousands of students and educators each year about ecology, science, and the beauty and wonders of the Sonoran Desert. During the first academic year (2009-2010), we achieved our goal of reaching nearly 20 teachers in 40 classrooms of 1000 students. We gave two 3-hour teacher-training sessions and provided nineteen 2.5-hour on-site evening sessions on dark skies activities for the students of the teachers trained. One outcome of the program was the contribution of 1000 "GLOBE at Night 2010” night-sky brightness measurements by Tucson students. Training sessions at similar levels are continuing this year. The partnership, planning, lesson learned, and outcomes of NOAO's collaboration with the environmental center will be presented.

  6. The Accuracy of RADIANCE Software in Modelling Overcast Sky Condition

    OpenAIRE

    Baharuddin

    2013-01-01

    A validation study of the sky models of RADIANCE simulation software against the overcast sky condition has been carried out in order to test the accuracy of sky model of RADIANCE for modeling the overcast sky condition in Hong Kong. Two sets of data have been analysed. Firstly, data collected from a set of experiments using a physical scale model. In this experiment, the illuminance of four points inside the model was measured under real sky conditions. Secondly, the RADIANCE simulation has ...

  7. Protecting the Local Dark-Sky Areas around the International Observatories in Chile.

    Science.gov (United States)

    Smith, M. G.

    2001-12-01

    This report covers efforts by IAU Commission 50's new Working Group on Light Pollution to slow or halt the spread of incipient light pollution near the VLT, the Magellan 6.5m telescopes, Gemini South, SOAR, Blanco and many smaller telescopes in Chile. An effort has just begun to protect the ALMA site in Northern Chile from RFI. Such work includes extensive outreach programs to the local population, schools and industry as well as to local, regional and national levels of government in Chile. The group is working internationally with such organizations as the IDA; one member has recently led the production of "The first world atlas of the artificial night-sky brightness". These efforts have resulted in the first national-level environmental legislation covering dark skies as part of a government effort to protect the environment. Chilean manufacturers are now producing competitive, full-cut-off, street lighting designed specifically to comply with the new legislation. The Chilean national tourism agency is supporting "Astronomical Tourism" based on the dark, clear skies of Chile. An international conference on Controlling Light Pollution and RFI will be held in La Serena, Chile on 5-7 March, 2002, backed up by a parallel meeting of Chilean amateur astronomers. Much work remains to be done. Most of this work is supported by funding from the US National Science Foundation through CTIO, and from ESO, OCIW and CONAMA.

  8. (an)isotropy of the X-ray sky

    International Nuclear Information System (INIS)

    Shafer, R.A.; Fabian, A.C.

    1983-01-01

    An assessment is made of the extent to which the study of the isotropy of the X-ray sky has contributed to the present understanding of the structure of the universe at moderate redshifts. It is, of course, the anisotropic character of the sky flux that is valuable in this context. Although it is not currently possible to undertake measurements with the precision and small solid angles that are typically achieved in the microwave range, the comparatively crude limits from the X-ray fluctuations place limits on the largest scale structure of the universe. After indicating the nature of measurements made, with the HEAO 1 A-2 experiment, of the X-ray sky and its anisotropies, it is shown how these place limits on the origin of the X-ray sky and on any large scale structure of the universe. 40 references

  9. 76 FR 45730 - Customer Clearing Documentation and Timing of Acceptance for Clearing

    Science.gov (United States)

    2011-08-01

    ... proposing regulations to facilitate customer access to clearing and to bolster risk management through... and execution of customer transactions on a DCM or SEF on terms that have a reasonable relationship to... a reasonable relationship to the best terms available by prohibiting restrictions in customer...

  10. Fading Skies

    Science.gov (United States)

    Sio, Betsy Menson

    2009-01-01

    A sky fading from blue to white to red at the horizon, and water darkening from light to midnight blue. Strong diagonals slashing through the image, drawing a viewer's eyes deeper into the picture, and delicate trees poised to convey a sense of beauty. These are the fascinating strengths of the ukiyo-e woodblock prints of Japanese artist Ando…

  11. Dark Skies Awareness Programs for the International Year of Astronomy

    Science.gov (United States)

    Walker, C. E.; Pompea, S. M.

    2008-12-01

    The loss of a dark night sky as a natural resource is a growing concern. It impacts not only astronomical research, but also our environment in terms of ecology, health, safety, economics and energy conservation. For this reason, "Dark Skies are a Universal Resource" is a cornerstone project for the U.S. International Year of Astronomy (IYA) program in 2009. Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people involved in a variety of dark skies-related programs. These programs focus on citizen-scientist sky-brightness monitoring programs, a planetarium show, podcasting, social networking, a digital photography contest, the Good Neighbor Lighting Program, Earth Hour, National Dark Skies Week, a traveling exhibit, a video tutorial, Dark Skies Discovery Sites, Astronomy Nights in the (National) Parks, Sidewalk Astronomy, and a Quiet Skies program. Many similar programs are available internationally through the "Dark Skies Awareness" Global Cornerstone Project. Working groups for both the national and international dark skies cornerstone projects are being chaired by the National Optical Astronomy Observatory (NOAO). The presenters from NOAO will provide the "know-how" and the means for session participants to become community advocates in promoting Dark Skies programs as public events at their home institutions. Participants will be able to get information on jump-starting their education programs through the use of well-developed instructional materials and kits. For more information, visit http://astronomy2009.us/darkskies/ and http://www.darkskiesawareness.org/.

  12. SkyNet: A Modular Nuclear Reaction Network Library

    Science.gov (United States)

    Lippuner, Jonas; Roberts, Luke F.

    2017-12-01

    Almost all of the elements heavier than hydrogen that are present in our solar system were produced by nuclear burning processes either in the early universe or at some point in the life cycle of stars. In all of these environments, there are dozens to thousands of nuclear species that interact with each other to produce successively heavier elements. In this paper, we present SkyNet, a new general-purpose nuclear reaction network that evolves the abundances of nuclear species under the influence of nuclear reactions. SkyNet can be used to compute the nucleosynthesis evolution in all astrophysical scenarios where nucleosynthesis occurs. SkyNet is free and open source, and aims to be easy to use and flexible. Any list of isotopes can be evolved, and SkyNet supports different types of nuclear reactions. SkyNet is modular so that new or existing physics, like nuclear reactions or equations of state, can easily be added or modified. Here, we present in detail the physics implemented in SkyNet with a focus on a self-consistent transition to and from nuclear statistical equilibrium to non-equilibrium nuclear burning, our implementation of electron screening, and coupling of the network to an equation of state. We also present comprehensive code tests and comparisons with existing nuclear reaction networks. We find that SkyNet agrees with published results and other codes to an accuracy of a few percent. Discrepancies, where they exist, can be traced to differences in the physics implementations.

  13. STARS4ALL Night Sky Brightness Photometer

    Directory of Open Access Journals (Sweden)

    Jaime Zamorano

    2017-06-01

    Full Text Available We present the main features of TESS-W, the first version of a series of inexpensive but reliable photometers that will be used to measure night sky brightness. The bandpass is extended to the red with respect of that of the Sky Quality Meter (SQM. TESS-W connects to a router via WIFI and it sends automatically the brightness values to a data repository using Internet of Things protocols. The device includes an infrared sensor to estimate the cloud coverage. It is designed for fixed stations to monitor the evolution of the sky brightness. The photometer could also be used in local mode connected to a computer or tablet to gather data from a moving vehicle. The photometer is being developed within STARS4ALL project, a collective awareness platform for promoting dark skies in Europe, funded by the EU. We intend to extend the existing professional networks to a citizen-based network of photometers. 

  14. A Lookup-Table-Based Approach to Estimating Surface Solar Irradiance from Geostationary and Polar-Orbiting Satellite Data

    Directory of Open Access Journals (Sweden)

    Hailong Zhang

    2018-03-01

    -of-the-art studies suggests that our proposed method can successfully estimate SSI with a maximum improvement of an RMSE of 24 W/m2. The clear-sky SSI retrieval was sensitive to aerosol optical thickness, which was largely dependent on the diurnal surface reflectance accuracy. Uncertainty in the pre-defined horizontal visibility for ‘clearest sky’ will eventually lead to considerable SSI retrieval error. Compared to cloud effective radius, the retrieval error of cloud optical thickness was a primary factor that determined the SSI estimation accuracy for cloudy skies. Our proposed method can be used to estimate SSI for clear and one-layer cloud sky, but is not suitable for multi-layer clouds overlap conditions as a lower-level cloud cannot be detected by the optical sensor when a higher-level cloud has a higher optical thickness.

  15. 77 FR 30032 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Order Approving Proposed Rule...

    Science.gov (United States)

    2012-05-21

    ... the One-Pot Cross- Margining Program With New York Portfolio Clearing, LLC to Certain ``Market... a Set of Market Professional Cross-Margining Accounts would be required to enter into Clearing... FICC and NYPC will not permit Clearing Members to enter into Market Professional Agreements until all...

  16. CLARA-SAL: a global 28 yr timeseries of Earth's black-sky surface albedo

    Directory of Open Access Journals (Sweden)

    A. Riihelä

    2013-04-01

    Full Text Available We present a novel 28 yr dataset of Earth's black-sky surface albedo, derived from AVHRR instruments. The dataset is created using algorithms to separately derive the surface albedo for different land use areas globally. Snow, sea ice, open water and vegetation are all treated independently. The product features corrections for the atmospheric effect in satellite-observed surface radiances, a BRDF correction for the anisotropic reflectance properties of natural surfaces, and a novel topography correction of geolocation and radiometric accuracy of surface reflectance observations over mountainous areas. The dataset is based on a homogenized AVHRR radiance timeseries. The product is validated against quality-controlled in situ observations of clear-sky surface albedo at various BSRN sites around the world. Snow and ice albedo retrieval validation is given particular attention using BSRN sites over Antarctica, Greenland Climate Network stations on the Greenland Ice Sheet (GrIS, as well as sea ice albedo data from the SHEBA and Tara expeditions. The product quality is found to be comparable to other previous long-term surface albedo datasets from AVHRR.

  17. Weather and atmosphere observation with the ATOM all-sky camera

    Directory of Open Access Journals (Sweden)

    Jankowsky Felix

    2015-01-01

    Full Text Available The Automatic Telescope for Optical Monitoring (ATOM for H.E.S.S. is an 75 cm optical telescope which operates fully automated. As there is no observer present during observation, an auxiliary all-sky camera serves as weather monitoring system. This device takes an all-sky image of the whole sky every three minutes. The gathered data then undergoes live-analysis by performing astrometric comparison with a theoretical night sky model, interpreting the absence of stars as cloud coverage. The sky monitor also serves as tool for a meteorological analysis of the observation site of the the upcoming Cherenkov Telescope Array. This overview covers design and benefits of the all-sky camera and additionally gives an introduction into current efforts to integrate the device into the atmosphere analysis programme of H.E.S.S.

  18. HST HOT-JUPITER TRANSMISSION SPECTRAL SURVEY: CLEAR SKIES FOR COOL SATURN WASP-39b

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Patrick D.; Knutson, Heather A. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Sing, David K.; Kataria, Tiffany; Nikolov, Nikolay [Astrophysics Group, School of Physics, University of Exeter, Stocker Road, Exeter, EX4 4QL (United Kingdom); Henry, Gregory W.; Williamson, Michael W. [Center of Excellence in Information Systems, Tennessee State University, Nashville, TN 37209 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California Santa Cruz, CA 95064 (United States); Burrows, Adam S. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Showman, Adam P.; Ballester, Gilda E. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Désert, Jean-Michel [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Aigrain, Suzanne [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Deming, Drake [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Etangs, Alain Lecavelier des; Vidal-Madjar, Alfred [CNRS, Institut dAstrophysique de Paris, UMR 7095, 98bis boulevard Arago, F-75014 Paris (France)

    2016-08-10

    We present the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) optical transmission spectroscopy of the cool Saturn-mass exoplanet WASP-39b from 0.29-1.025 μ m, along with complementary transit observations from Spitzer IRAC at 3.6 and 4.5 μ m. The low density and large atmospheric pressure scale height of WASP-39b make it particularly amenable to atmospheric characterization using this technique. We detect a Rayleigh scattering slope as well as sodium and potassium absorption features; this is the first exoplanet in which both alkali features are clearly detected with the extended wings predicted by cloud-free atmosphere models. The full transmission spectrum is well matched by a clear H{sub 2}-dominated atmosphere, or one containing a weak contribution from haze, in good agreement with the preliminary reduction of these data presented in Sing et al. WASP-39b is predicted to have a pressure-temperature profile comparable to that of HD 189733b and WASP-6b, making it one of the coolest transiting gas giants observed in our HST STIS survey. Despite this similarity, WASP-39b appears to be largely cloud-free, while the transmission spectra of HD 189733b and WASP-6b both indicate the presence of high altitude clouds or hazes. These observations further emphasize the surprising diversity of cloudy and cloud-free gas giant planets in short-period orbits and the corresponding challenges associated with developing predictive cloud models for these atmospheres.

  19. 76 FR 37162 - Self-Regulatory Organizations; The Options Clearing Corporation; Order Approving Proposed Rule...

    Science.gov (United States)

    2011-06-24

    ... of OCC's Internal Cross-Margining Program To Include the Ability of a Pair of Affiliated Clearing... change is to expand OCC's internal cross- margining program to permit a pair of affiliated clearing... program for affiliated clearing members until after such time that the CFTC has issued an order or amended...

  20. Cloud classification in a mediterranean location using radiation data and sky images

    International Nuclear Information System (INIS)

    Martinez-Chico, M.; Batlles, F.J.; Bosch, J.L.

    2011-01-01

    Knowledge regarding the solar radiation reaching the earth's surface and its geographical distribution is very important for the use of solar energy as a resource to produce electricity. Therefore, a proper assessment of available solar resource is particularly important to determine the placement and operation of solar thermal power plants. To perform this analysis correctly, it is necessary to determine the main factors influencing the radiation reaching the earth's surface, such as the earth's geometry, terrain, and atmospheric attenuation by gases, particles and clouds. Among these factors, it is important to emphasise the role of clouds as the main attenuating factor of radiation. Information about the amount and type of clouds present in the sky is therefore necessary to analyse both their attenuation levels and the prevalence of different sky conditions. Cloud cover is characterised according to attenuation levels, using the beam transmittance (k b , ratio of direct radiation incident on the surface to the extraterrestrial solar radiation) and hemispherical sky images. An analysis of the frequency and duration of each type of cloud cover blocking the sun's disk is also performed. Results show prevailing sky situations that make the studied area very suitable for the use of solar energy systems. -- Highlights: → Beam transmittance index k b have been used successfully to classify the cloud cover. → The proposed classification has been used to study a Mediterranean location in south-eastern Spain. → Percentage of cloudless/cloudy situations showed a good potential for solar energy applications in the studied area.

  1. The pre-launch Planck Sky Model: a model of sky emission at submillimetre to centimetre wavelengths

    CERN Document Server

    Delabrouille, J.; Melin, J.-B.; Miville-Deschenes, M.-A.; Gonzalez-Nuevo, J.; Jeune, M.Le; Castex, G.; de Zotti, G.; Basak, S.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A.; Bernard, J.-P.; Bouchet, F.R.; Clements, D.L.; da Silva, A.; Dickinson, C.; Dodu, F.; Dolag, K.; Elsner, F.; Fauvet, L.; Fay, G.; Giardino, G.; Leach, S.; Lesgourgues, J.; Liguori, M.; Macias-Perez, J.F.; Massardi, M.; Matarrese, S.; Mazzotta, P.; Montier, L.; Mottet, S.; Paladini, R.; Partridge, B.; Piffaretti, R.; Prezeau, G.; Prunet, S.; Ricciardi, S.; Roman, M.; Schaefer, B.; Toffolatti, L.

    2012-01-01

    We present the Planck Sky Model (PSM), a parametric model for the generation of all-sky, few arcminute resolution maps of sky emission at submillimetre to centimetre wavelengths, in both intensity and polarisation. Several options are implemented to model the cosmic microwave background, Galactic diffuse emission (synchrotron, free-free, thermal and spinning dust, CO lines), Galactic H-II regions, extragalactic radio sources, dusty galaxies, and thermal and kinetic Sunyaev-Zeldovich signals from clusters of galaxies. Each component is simulated by means of educated interpolations/extrapolations of data sets available at the time of the launch of the Planck mission, complemented by state-of-the-art models of the emission. Distinctive features of the simulations are: spatially varying spectral properties of synchrotron and dust; different spectral parameters for each point source; modeling of the clustering properties of extragalactic sources and of the power spectrum of fluctuations in the cosmic infrared back...

  2. 78 FR 75413 - Self-Regulatory Organizations; National Securities Clearing Corporation; Order Approving Proposed...

    Science.gov (United States)

    2013-12-11

    ... Modified by Amendment Nos. 1, 2, and 3, To Institute Supplemental Liquidity Deposits to Its Clearing Fund Designed To Increase Liquidity Resources To Meet Its Liquidity Needs December 5, 2013. I. Introduction On... Change'') to institute supplemental liquidity deposits to NSCC's Clearing Fund designed to increase...

  3. Submission to Ofcom: Invitation to comment for public interest test on the proposed acquisition of Sky plc by Twenty-First Century Fox, Inc.:Consultation response from the Centre for Competition Policy

    OpenAIRE

    Broughton Micova, Sarah; Reader, David

    2017-01-01

    The authors welcome the opportunity to respond to Ofcom’s invitation to comment on the application of the public interest test to the proposed Sky/21st Century Fox transaction. There already exists an abundance of evidence relating to Sky’s news production and distribution, as well as the prominence of its news content and that of the other news companies run by its senior management, which raise media plurality concerns in relation to this deal.1 We trust that Ofcom will be diligent and crea...

  4. 77 FR 75466 - Self-Regulatory Organizations; Options Clearing Corporation; Order Approving Proposed Rule Change...

    Science.gov (United States)

    2012-12-20

    ....\\8\\ This includes the potential use of the clearing fund as a source of liquidity should it ever be... reduce the risk that the assets in the clearing fund might at any time be insufficient to enable OCC to... Determining the Minimum Clearing Fund Size To Include Consideration of the Amount Necessary To Draw on Secured...

  5. Design of a device for sky light polarization measurements.

    Science.gov (United States)

    Wang, Yujie; Hu, Xiaoping; Lian, Junxiang; Zhang, Lilian; Xian, Zhiwen; Ma, Tao

    2014-08-14

    Sky polarization patterns can be used both as indicators of atmospheric turbidity and as a sun compass for navigation. The objective of this study is to improve the precision of sky light polarization measurements by optimal design of the device used. The central part of the system is composed of a Charge Coupled Device (CCD) camera; a fish-eye lens and a linear polarizer. Algorithms for estimating parameters of the polarized light based on three images are derived and the optimal alignments of the polarizer are analyzed. The least-squares estimation is introduced for sky light polarization pattern measurement. The polarization patterns of sky light are obtained using the designed system and they follow almost the same patterns of the single-scattering Rayleigh model. Deviations of polarization angles between observation and the theory are analyzed. The largest deviations occur near the sun and anti-sun directions. Ninety percent of the deviations are less than 5° and 40% percent of them are less than 1°. The deviations decrease evidently as the degree of polarization increases. It also shows that the polarization pattern of the cloudy sky is almost identical as in the blue sky.

  6. Modelling and Display of the Ultraviolet Sky

    Science.gov (United States)

    Daniels, J.; Henry, R.; Murthy, J.; Allen, M.; McGlynn, T. A.; Scollick, K.

    1994-12-01

    A computer program is currently under development to model in 3D - one dimension of which is wavelength - all the known and major speculated sources of ultraviolet (900 A - 3100 A ) radiation over the celestial sphere. The software is being written in Fortran 77 and IDL and currently operates under IRIX (the operating system of the Silicon Graphics Iris Machine); all output models are in FITS format. Models along with display software will become available to the astronomical community. The Ultraviolet Sky Model currently includes the Zodiacal Light, Point Sources of Emission, and the Diffuse Galactic Light. The Ultraviolet Sky Model is currently displayed using SkyView: a package under development at NASA/ GSFC, which allows users to retrieve and display publically available all-sky astronomical survey data (covering many wavebands) over the Internet. We present a demonstration of the SkyView display of the Ultraviolet Model. The modelling is a five year development project: the work illustrated here represents product output at the end of year one. Future work includes enhancements to the current models and incorporation of the following models: Galactic Molecular Hydrogen Fluorescence; Galactic Highly Ionized Atomic Line Emission; Integrated Extragalactic Light; and speculated sources in the intergalactic medium such as Ionized Plasma and radiation from Non-Baryonic Particle Decay. We also present a poster which summarizes the components of the Ultraviolet Sky Model and outlines a further package that will be used to display the Ultraviolet Model. This work is supported by United States Air Force Contract F19628-93-K-0004. Dr J. Daniels is supported with a post-doctoral Fellowship from the Leverhulme Foundation, London, United Kingdom. We are also grateful for the encouragement of Dr Stephen Price (Phillips Laboratory, Hanscomb Air Force Base, MA)

  7. Day/night whole sky imagers for 24-h cloud and sky assessment: history and overview.

    Science.gov (United States)

    Shields, Janet E; Karr, Monette E; Johnson, Richard W; Burden, Art R

    2013-03-10

    A family of fully automated digital whole sky imagers (WSIs) has been developed at the Marine Physical Laboratory over many years, for a variety of research and military applications. The most advanced of these, the day/night whole sky imagers (D/N WSIs), acquire digital imagery of the full sky down to the horizon under all conditions from full sunlight to starlight. Cloud algorithms process the imagery to automatically detect the locations of cloud for both day and night. The instruments can provide absolute radiance distribution over the full radiance range from starlight through daylight. The WSIs were fielded in 1984, followed by the D/N WSIs in 1992. These many years of experience and development have resulted in very capable instruments and algorithms that remain unique. This article discusses the history of the development of the D/N WSIs, system design, algorithms, and data products. The paper cites many reports with more detailed technical documentation. Further details of calibration, day and night algorithms, and cloud free line-of-sight results will be discussed in future articles.

  8. Stability of the nine sky quality meters in the Dutch night sky brightness monitoring network.

    Science.gov (United States)

    den Outer, Peter; Lolkema, Dorien; Haaima, Marty; van der Hoff, Rene; Spoelstra, Henk; Schmidt, Wim

    2015-04-22

    In the context of monitoring abundance of artificial light at night, the year-to-year stability of Sky Quality Meters (SQMs) is investigated by analysing intercalibrations derived from two measurement campaigns that were held in 2011 and 2012. An intercalibration comprises a light sensitivity factor and an offset for each SQM. The campaigns were concerned with monitoring measurements, each lasting one month. Nine SQMs, together forming the Night Sky Brightness Monitoring network (MHN) in The Netherlands, were involved in both campaigns. The stability of the intercalibration of these instruments leads to a year-to-year uncertainty (standard deviation) of 5% in the measured median luminance occurring at the MHN monitoring locations. For the 10-percentiles and 90-percentiles, we find 8% and 4%, respectively. This means that, for urban and industrial areas, changes in the sky brightness larger than 5% become detectable. Rural and nature areas require an 8%-9% change of the median luminance to be detectable. The light sensitivety agrees within 8% for the whole group of SQMs.

  9. Reflective all-sky thermal infrared cloud imager.

    Science.gov (United States)

    Redman, Brian J; Shaw, Joseph A; Nugent, Paul W; Clark, R Trevor; Piazzolla, Sabino

    2018-04-30

    A reflective all-sky imaging system has been built using a long-wave infrared microbolometer camera and a reflective metal sphere. This compact system was developed for measuring spatial and temporal patterns of clouds and their optical depth in support of applications including Earth-space optical communications. The camera is mounted to the side of the reflective sphere to leave the zenith sky unobstructed. The resulting geometric distortion is removed through an angular map derived from a combination of checkerboard-target imaging, geometric ray tracing, and sun-location-based alignment. A tape of high-emissivity material on the side of the reflector acts as a reference that is used to estimate and remove thermal emission from the metal sphere. Once a bias that is under continuing study was removed, sky radiance measurements from the all-sky imager in the 8-14 μm wavelength range agreed to within 0.91 W/(m 2 sr) of measurements from a previously calibrated, lens-based infrared cloud imager over its 110° field of view.

  10. An All-Sky Portable (ASP) Optical Catalogue

    Science.gov (United States)

    Flesch, Eric Wim

    2017-06-01

    This optical catalogue combines the all-sky USNO-B1.0/A1.0 and most-sky APM catalogues, plus overlays of SDSS optical data, into a single all-sky map presented in a sparse binary format that is easily downloaded at 9 Gb zipped. Total count is 1 163 237 190 sources and each has J2000 astrometry, red and blue magnitudes with PSFs and variability indicator, and flags for proper motion, epoch, and source survey and catalogue for each of the photometry and astrometry. The catalogue is available on http://quasars.org/asp.html, and additional data for this paper is available at http://dx.doi.org/10.4225/50/5807fbc12595f.

  11. 76 FR 20063 - Self-Regulatory Organizations; The Options Clearing Corporation; Order Approving a Proposed Rule...

    Science.gov (United States)

    2011-04-11

    ... that has a clearing relationship with an OCC clearing member participating in the Market Loan Program... and guarantees the return of the loaned stock to the lending clearing member and the return of the... the clearing member's options account at OCC and, to the extent that they offset the risk of options...

  12. Measuring high-resolution sky luminance distributions with a CCD camera.

    Science.gov (United States)

    Tohsing, Korntip; Schrempf, Michael; Riechelmann, Stefan; Schilke, Holger; Seckmeyer, Gunther

    2013-03-10

    We describe how sky luminance can be derived from a newly developed hemispherical sky imager (HSI) system. The system contains a commercial compact charge coupled device (CCD) camera equipped with a fish-eye lens. The projection of the camera system has been found to be nearly equidistant. The luminance from the high dynamic range images has been calculated and then validated with luminance data measured by a CCD array spectroradiometer. The deviation between both datasets is less than 10% for cloudless and completely overcast skies, and differs by no more than 20% for all sky conditions. The global illuminance derived from the HSI pictures deviates by less than 5% and 20% under cloudless and cloudy skies for solar zenith angles less than 80°, respectively. This system is therefore capable of measuring sky luminance with the high spatial and temporal resolution of more than a million pixels and every 20 s respectively.

  13. The Mythology of the Night Sky

    Science.gov (United States)

    Falkner, David E.

    The word "planet" comes from the Latin word planeta and the Greek word planes, which means "wanderer." When the ancient Greeks studied the night sky they noticed that most of the stars remained in the same position relative to all the other stars, but a few stars seem to move in the sky from day to day, week to week, and month to month. The Greeks called these rogue stars "wanderers" because they wandered through the starry background.

  14. The VLA Sky Survey

    Science.gov (United States)

    Lacy, Mark; VLASS Survey Team, VLASS Survey Science Group

    2018-01-01

    The VLA Sky Survey (VLASS), which began in September 2017, is a seven year project to image the entire sky north of Declination -40 degrees in three epochs. The survey is being carried out in I,Q and U polarization at a frequency of 2-4GHz, and a resolution of 2.5 arcseconds, with each epoch being separated by 32 months. Raw data from the survey, along with basic "quicklook" images are made freely available shortly after observation. Within a few months, NRAO will begin making available further basic data products, including refined images and source lists. In this talk I shall describe the science goals and methodology of the survey, the current survey status, and some early results, along with plans for collaborations with external groups to produce enhanced, high level data products.

  15. An Enhanced Method for Scheduling Observations of Large Sky Error Regions for Finding Optical Counterparts to Transients

    Energy Technology Data Exchange (ETDEWEB)

    Rana, Javed; Singhal, Akshat; Gadre, Bhooshan; Bhalerao, Varun; Bose, Sukanta, E-mail: javed@iucaa.in [Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411 007 (India)

    2017-04-01

    The discovery and subsequent study of optical counterparts to transient sources is crucial for their complete astrophysical understanding. Various gamma-ray burst (GRB) detectors, and more notably the ground-based gravitational wave detectors, typically have large uncertainties in the sky positions of detected sources. Searching these large sky regions spanning hundreds of square degrees is a formidable challenge for most ground-based optical telescopes, which can usually image less than tens of square degrees of the sky in a single night. We present algorithms for better scheduling of such follow-up observations in order to maximize the probability of imaging the optical counterpart, based on the all-sky probability distribution of the source position. We incorporate realistic observing constraints such as the diurnal cycle, telescope pointing limitations, available observing time, and the rising/setting of the target at the observatory’s location. We use simulations to demonstrate that our proposed algorithms outperform the default greedy observing schedule used by many observatories. Our algorithms are applicable for follow-up of other transient sources with large positional uncertainties, such as Fermi -detected GRBs, and can easily be adapted for scheduling radio or space-based X-ray follow-up.

  16. Teaching Astronomy Through Art: Under Southern Skies -- Aboriginal and Western Scientific Perspectives of the Australian Night Sky

    Science.gov (United States)

    Majewski, S. R.; Boles, M. S.; Patterson, R. J.

    1999-12-01

    We have created an exhibit, Under Southern Skies -- Aboriginal and Western Scientific Perspectives of the Australian Night Sky, which has shown since June, 1999 in newly refurbished exhibit space at the Leander McCormick Observatory. The University of Virginia has a long and continuing tradition of astrometry starting with early parallax work at the McCormick Observatory, extending to our own NSF CAREER Award-funded projects, and including a long-term, ongoing southern parallax program at Mt. Stromlo and Siding Springs Observatories in Australia. Recently, through a gift of Mr. John Kluge, the University of Virginia has obtained one of the most extensive collections of Australian Aboriginal art outside of Australia. The goal of our exhibit is to unite the University's scientific, artistic and cultural connections to Australia through an exhibit focusing on different perspectives of the Australian night sky. We have brought together Australian Aboriginal bark and canvas paintings that feature astronomical themes, e.g., Milky Way, Moon, Magellanic Cloud and Seven Sisters Dreamings, from the Kluge-Ruhe and private collections. These paintings, from the Central Desert and Arnhem Land regions of Australia, are intermingled with modern, large format, color astronomical images of the same scenes. Descriptive panels and a small gallery guide explain the cultural, artistic and scientific aspects of the various thematic groupings based on particular southern hemisphere night sky objects and associated Aboriginal traditions and stories. This unusual combination of art and science not only provides a unique avenue for educating the public about both astronomy and Australian Aboriginal culture, but highlights mankind's ancient and continuing connection to the night sky. We appreciate funding from NSF CAREER Award #AST-9702521, a Cottrell Scholar Award from The Research Corporation, and the Dept. of Astronomy and Ruhe-Kluge Collection at the University of Virginia.

  17. Optical Sky Brightness and Transparency during the Winter Season at Dome A Antarctica from the Gattini-All-Sky Camera

    Science.gov (United States)

    Yang, Yi; Moore, Anna M.; Krisciunas, Kevin; Wang, Lifan; Ashley, Michael C. B.; Fu, Jianning; Brown, Peter J.; Cui, Xiangqun; Feng, Long-Long; Gong, Xuefei; Hu, Zhongwen; Lawrence, Jon S.; Luong-Van, Daniel; Riddle, Reed L.; Shang, Zhaohui; Sims, Geoff; Storey, John W. V.; Suntzeff, Nicholas B.; Tothill, Nick; Travouillon, Tony; Yang, Huigen; Yang, Ji; Zhou, Xu; Zhu, Zhenxi

    2017-07-01

    The summit of the Antarctic plateau, Dome A, is proving to be an excellent site for optical, near-infrared, and terahertz astronomical observations. Gattini is a wide-field camera installed on the PLATO instrument module as part of the Chinese-led traverse to Dome A in 2009 January. We present here the measurements of sky brightness with the Gattini ultra-large field of view (90^\\circ × 90^\\circ ) in the photometric B-, V-, and R-bands; cloud cover statistics measured during the 2009 winter season; and an estimate of the sky transparency. A cumulative probability distribution indicates that the darkest 10% of the nights at Dome A have sky brightness of S B = 22.98, S V = 21.86, and S R = 21.68 mag arcsec-2. These values were obtained during the year 2009 with minimum aurora, and they are comparable to the faintest sky brightness at Maunakea and the best sites of northern Chile. Since every filter includes strong auroral lines that effectively contaminate the sky brightness measurements, for instruments working around the auroral lines, either with custom filters or with high spectral resolution instruments, these values could be easily obtained on a more routine basis. In addition, we present example light curves for bright targets to emphasize the unprecedented observational window function available from this ground-based site. These light curves will be published in a future paper.

  18. Basic Blue Skies Research in the UK: Are we losing out?

    Science.gov (United States)

    Linden, Belinda

    2008-02-29

    The term blue skies research implies a freedom to carry out flexible, curiosity-driven research that leads to outcomes not envisaged at the outset. This research often challenges accepted thinking and introduces new fields of study. Science policy in the UK has given growing support for short-term goal-oriented scientific research projects, with pressure being applied on researchers to demonstrate the future application of their work. These policies carry the risk of restricting freedom, curbing research direction, and stifling rather than stimulating the creativity needed for scientific discovery. This study tracks the tortuous routes that led to three major discoveries in cardiology. It then investigates the constraints in current research, and opportunities that may be lost with existing funding processes, by interviewing selected scientists and fund providers for their views on curiosity-driven research and the freedom needed to allow science to flourish. The transcripts were analysed using a grounded theory approach to gather recurrent themes from the interviews. The results from these interviews suggest that scientists often cannot predict the future applications of research. Constraints such as lack of scientific freedom, and a narrow focus on relevance and accountability were believed to stifle the discovery process. Although it was acknowledged that some research projects do need a clear and measurable framework, the interviewees saw a need for inquisitive, blue skies research to be managed in a different way. They provided examples of situations where money allocated to 'safe' funding was used for more innovative research. This sample of key UK scientists and grant providers acknowledge the importance of basic blue skies research. Yet the current evaluation process often requires that scientists predict their likely findings and estimate short-term impact, which does not permit freedom of research direction. There is a vital need for prominent scientists

  19. The night sky brightness at McDonald Observatory

    Science.gov (United States)

    Kalinowski, J. K.; Roosen, R. G.; Brandt, J. C.

    1975-01-01

    Baseline observations of the night sky brightness in B and V are presented for McDonald Observatory. In agreement with earlier work by Elvey and Rudnick (1937) and Elvey (1943), significant night-to-night and same-night variations in sky brightness are found. Possible causes for these variations are discussed. The largest variation in sky brightness found during a single night is approximately a factor of two, a value which corresponds to a factor-of-four variation in airglow brightness. The data are used to comment on the accuracy of previously published surface photometry of M 81.

  20. Mining the SDSS SkyServer SQL queries log

    Science.gov (United States)

    Hirota, Vitor M.; Santos, Rafael; Raddick, Jordan; Thakar, Ani

    2016-05-01

    SkyServer, the Internet portal for the Sloan Digital Sky Survey (SDSS) astronomic catalog, provides a set of tools that allows data access for astronomers and scientific education. One of SkyServer data access interfaces allows users to enter ad-hoc SQL statements to query the catalog. SkyServer also presents some template queries that can be used as basis for more complex queries. This interface has logged over 330 million queries submitted since 2001. It is expected that analysis of this data can be used to investigate usage patterns, identify potential new classes of queries, find similar queries, etc. and to shed some light on how users interact with the Sloan Digital Sky Survey data and how scientists have adopted the new paradigm of e-Science, which could in turn lead to enhancements on the user interfaces and experience in general. In this paper we review some approaches to SQL query mining, apply the traditional techniques used in the literature and present lessons learned, namely, that the general text mining approach for feature extraction and clustering does not seem to be adequate for this type of data, and, most importantly, we find that this type of analysis can result in very different queries being clustered together.

  1. The BlueSky Smoke Modeling Framework: Recent Developments

    Science.gov (United States)

    Sullivan, D. C.; Larkin, N.; Raffuse, S. M.; Strand, T.; ONeill, S. M.; Leung, F. T.; Qu, J. J.; Hao, X.

    2012-12-01

    BlueSky systems—a set of decision support tools including SmartFire and the BlueSky Framework—aid public policy decision makers and scientific researchers in evaluating the air quality impacts of fires. Smoke and fire managers use BlueSky systems in decisions about prescribed burns and wildland firefighting. Air quality agencies use BlueSky systems to support decisions related to air quality regulations. We will discuss a range of recent improvements to the BlueSky systems, as well as examples of applications and future plans. BlueSky systems have the flexibility to accept basic fire information from virtually any source and can reconcile multiple information sources so that duplication of fire records is eliminated. BlueSky systems currently apply information from (1) the National Oceanic and Atmospheric Administration's (NOAA) Hazard Mapping System (HMS), which represents remotely sensed data from the Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Very High Resolution Radiometer (AVHRR), and Geostationary Operational Environmental Satellites (GOES); (2) the Monitoring Trends in Burn Severity (MTBS) interagency project, which derives fire perimeters from Landsat 30-meter burn scars; (3) the Geospatial Multi-Agency Coordination Group (GeoMAC), which produces helicopter-flown burn perimeters; and (4) ground-based fire reports, such as the ICS-209 reports managed by the National Wildfire Coordinating Group. Efforts are currently underway to streamline the use of additional ground-based systems, such as states' prescribed burn databases. BlueSky systems were recently modified to address known uncertainties in smoke modeling associated with (1) estimates of biomass consumption derived from sparse fuel moisture data, and (2) models of plume injection heights. Additional sources of remotely sensed data are being applied to address these issues as follows: - The National Aeronautics and Space Administration's (NASA) Tropical Rainfall Measuring Mission

  2. SkyDiscovery: Humans and Machines Working Together

    Science.gov (United States)

    Donalek, Ciro; Fang, K.; Drake, A. J.; Djorgovski, S. G.; Graham, M. J.; Mahabal, A.; Williams, R.

    2011-01-01

    Synoptic sky surveys are now discovering tens to hundreds of transient events every clear night, and that data rate is expected to increase dramatically as we move towards the LSST. A key problem is classification of transients, which determines their scientific interest and possible follow-up. Some of the relevant information is contextual, and easily recognizable by humans looking at images, but it is very hard to encode in the data pipelines. Crowdsourcing (aka Citizen Science) provides one possible way to gather such information. SkyDiscovery.org is a website that allows experts and citizen science enthusiasts to work together and share information in a collaborative scientific discovery environment. Currently there are two projects running on the website. In the Event Classification project users help finding candidate transients through a series of questions related to the images shown. Event classification depends very much form the contextual information and humans are remarkably effective at recognizing noise in incomplete heterogeneous data and figuring out which contextual information is important. In the SNHunt project users are requested to look for new objects appearing on images of galaxies taken by the Catalina Real-time Transient Survey, in order to find all the supernovae occurring in nearby bright galaxies. Images are served alongside with other tools that can help the discovery. A multi level approach allows the complexity of the interface to be tailored to the expertise level of the user. An entry level user can just review images and validate events as being real, while a more advanced user would be able to interact with the data associated to an event. The data gathered will not be only analyzed and used directly for some specific science project, but also to train well-defined algorithms to be used in automating such data analysis in the future.

  3. Implementation of IAU Resolution 2009 B5, "in Defence of the night sky and the right to starlight"

    Science.gov (United States)

    Green, Richard F.; Walker, Constance Elaine

    2015-08-01

    IAU Resolution 2009 B5 calls on IAU members to protect the public`s right to an unpolluted night sky as well as the astronomical quality of the sky around major research observatories. The approach of Commission 50 - astronomical site protection - includes working with the lighting industry for appropriate products from rapidly evolving solid state technology, arming astronomers with training and materials for presentation, selective endorsement of key protection issues, cooperation with other IAU commissions for education and outreach with particular current attention to the International Year of Light, and provision of clear quantitative priorities for outdoor lighting standards. In 2012, these priorities were defined as full cut-off shielding, spectral management to minimize output shortward of 500 nm, and zone- and time-appropriate lighting levels. Revisiting the specifics of these priorities will be a topic for current discussion.

  4. Non-sky polarization-based dehazing algorithm for non-specular objects using polarization difference and global scene feature.

    Science.gov (United States)

    Qu, Yufu; Zou, Zhaofan

    2017-10-16

    Photographic images taken in foggy or hazy weather (hazy images) exhibit poor visibility and detail because of scattering and attenuation of light caused by suspended particles, and therefore, image dehazing has attracted considerable research attention. The current polarization-based dehazing algorithms strongly rely on the presence of a "sky area", and thus, the selection of model parameters is susceptible to external interference of high-brightness objects and strong light sources. In addition, the noise of the restored image is large. In order to solve these problems, we propose a polarization-based dehazing algorithm that does not rely on the sky area ("non-sky"). First, a linear polarizer is used to collect three polarized images. The maximum- and minimum-intensity images are then obtained by calculation, assuming the polarization of light emanating from objects is negligible in most scenarios involving non-specular objects. Subsequently, the polarization difference of the two images is used to determine a sky area and calculate the infinite atmospheric light value. Next, using the global features of the image, and based on the assumption that the airlight and object radiance are irrelevant, the degree of polarization of the airlight (DPA) is calculated by solving for the optimal solution of the correlation coefficient equation between airlight and object radiance; the optimal solution is obtained by setting the right-hand side of the equation to zero. Then, the hazy image is subjected to dehazing. Subsequently, a filtering denoising algorithm, which combines the polarization difference information and block-matching and 3D (BM3D) filtering, is designed to filter the image smoothly. Our experimental results show that the proposed polarization-based dehazing algorithm does not depend on whether the image includes a sky area and does not require complex models. Moreover, the dehazing image except specular object scenarios is superior to those obtained by Tarel

  5. Citizen Sky, IYA 2009 and What's To Come

    Science.gov (United States)

    Turner, Rebecca; Price, A.; Henden, A.

    2010-01-01

    Citizen Sky is a multi-year, NSF funded citizen science project involving the bright and mysterious variable star eps Aur. The project was conceived by the IYA 2009 working group on Research Experiences for Students, Teachers, and Citizen-Scientists. Citizen Sky is going beyond simple observing to include a major data analysis component. The goal is to introduce the participant to the full scientific process from background research to paper writing for a peer-reviewed journal. During IYA 2009 the Citizen Sky team was fully assembled, the website was developed and put online, and the first of two participant workshops was held. However, Citizen Sky does not stop or even slow down with the conclusion of IYA 2009. The project will continue to grow in the coming years. New participants are being recruited and trained as the observing phase of the project continues, a second participant workshop is planned for 2010, and the data analysis phase of the project will begin in earnest.

  6. Simultaneous measurement of spectral sky radiance by a non-scanning multidirectional spectroradiometer (MUDIS)

    International Nuclear Information System (INIS)

    Riechelmann, Stefan; Schrempf, Michael; Seckmeyer, Gunther

    2013-01-01

    We present a novel non-scanning multidirectional spectroradiometer (MUDIS) measuring the spectral sky radiance as a function of zenith and azimuth angle with a high spectral and temporal resolution. The instrument is based on a hyperspectral imager and measures spectral sky radiance in the wavelength range of 250–600 nm at 113 different directions simultaneously. MUDIS has been intercalibrated with a sky scanning CCD spectroradiometer (SCCD). Sky radiance measurements have been performed with both instruments under cloudless and overcast sky. The spectral actinic irradiance derived from those measurements agrees within 8% for wavelengths higher than 320 nm. The bias between synchronous MUDIS and SCCD sky radiance measurements during cloudless and overcast sky is below 5% for 320 and 500 nm with a 1σ standard deviation of less than 10%. MUDIS enables us to perform more than 220 000 spectral sky radiance measurements instead of approximately 6000 SCCD spectral sky radiance measurements per day and to measure spatial variations of spectral sky radiance simultaneously. (paper)

  7. The NexStar evolution and SkyPortal user's guide

    CERN Document Server

    Chen, James L

    2016-01-01

    This book serves as a comprehensive guide for using a Nexstar Evolution mount with WiFi SkyPortal control, walking the reader through the process for aligning and operating the system from a tablet or smartphone. The next generation Go-To mount from Celestron, this is compatible not only with the Nextstar Evolution but also with older mounts. It is the ideal resource for anyone who owns, or is thinking of owning, a Nexstar Evolution telescope, or adapting their existing Celestron mount. Pros and cons of the system are thoroughly covered with a critical depth that addresses any possible question by users. Beginning with a brief history of Go-To telescopes and the genesis of this still new technology, the author covers every aspect of the newly expanding capability in observing. This includes the associated Sky Portal smartphone and tablet application, the transition from the original Nexstar GoTo system to the new SkyPortal system, the use of the Sky Portal application with its Sky Safari 4 basic software and ...

  8. The VLA Sky Survey (VLASS): Overview and First Results

    Science.gov (United States)

    Myers, Steven T.; VLASS Survey Team, Survey Science Group (SSG)

    2018-01-01

    The VLA Sky Survey (VLASS) is a 5520 hour spectropolarimetric synoptic survey covering the 33885 square degrees of the sky above Declination -40 degrees from 2-4 GHz at 2.5" angular resolution using the upgraded Karl G. Jansky Very Large Array (VLA). Over the survey duration of 7 years, each area of the sky will be covered in 3 epochs spaced 32 months apart, to a projected depth of 0.12mJy/beam rms noise per epoch and 0.07mJy/beam for 3 epochs combined. The VLASS employs on-the-fly mosaicking (OTFM) to rapidly scan the sky with a net speed of approximately 20 sq. degrees per hour. The high-level science goals for the survey include the identification and precise location of radio transients, the measurement of magnetic fields in our galaxy and beyond, and the study of radio emission from galaxies and active galactic nuclei throughout the Universe. The ability of the VLASS to see through dust allows us to unveil phenomena such as hidden cosmic explosions, emission from deep within our galaxy, and supermassive black holes buried within host galaxies.The VLASS was proposed in 2014 by our community-led Survey Science Group (SSG). VLASS Pilot observations were taken in mid-2016, and the first epoch covering half the area (VLASS1.1) commenced in September 2017. The raw data from the VLASS are available in the NRAO archive immediately with no proprietary period. The Basic Data Products (BDP) that will be produced by the survey team are public and will additionally include: calibrated visibility data, quick-look continuum images (with a goal of posting to the archive within 1 week of observation), single-epoch and cumulative combined-epoch images, spectral image cubes, and basic object catalogs. Single-epoch and cumulative images are in intensity and linear polarization (Stokes IQU). In addition to the BDP provided by NRAO and served through the NRAO archive, there are plans for Enhanced Data Products and Services to be provided by the community in partnership with the

  9. SNAP sky background at the north ecliptic pole

    International Nuclear Information System (INIS)

    Aldering, Greg

    2002-01-01

    I summarize the extant direct and indirect data on the sky background SNAP will see at the North Ecliptic Pole over the wavelength range 0.4 < λ < 1.7 (micro)m. At the spatial resolution of SNAP the sky background due to stars and galaxies is resolved, so the only source considered is zodiacal light. Several models are explored to provide interpolation in wavelength between the broadband data from HST and COBE observations. I believe the input data are now established well enough that the accuracy of the sky background presented here is sufficient for SNAP simulations, and that it will stand up to scrutiny by reviewers

  10. 78 FR 18382 - Self-Regulatory Organizations; The Options Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2013-03-26

    ... Stock Loan/Hedge Program in a manner that protects the clearing system against risk through the same or... the By- Laws To Facilitate the Use of the Stock Loan/Hedge Program by Canadian Clearing Members March... the Stock Loan/Hedge Program by Canadian Clearing Members. II. Self-Regulatory Organization's...

  11. 76 FR 68236 - Self-Regulatory Organizations; Options Clearing Corporation; Order Approving Proposed Rule Change...

    Science.gov (United States)

    2011-11-03

    ... OCC has the governance structure in place to clear and settle the transactions that it clears and... must: (i) Establish governance arrangements that are transparent (I) To fulfill public interest... believes that its existing governance arrangements satisfy the transparency requirements of subparagraph (i...

  12. 78 FR 9088 - Self-Regulatory Organizations; ICE Clear Europe Limited; Order Approving Proposed Rule Change To...

    Science.gov (United States)

    2013-02-07

    ... provide updates related to anti- money laundering legislation applicable to customers, clarify membership... framework available for other products at ICE Clear Europe. US customers must clear through a registered... applicable. Non-US customers may clear through a non-US clearing member in accordance with applicable local...

  13. 77 FR 66900 - Self-Regulatory Organizations; The Options Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2012-11-07

    ... of the clearing fund as a source of liquidity should it ever be the case that OCC is unable to obtain... address the risk that the assets in the clearing fund might at any time be insufficient to enable OCC to... for Determining the Minimum Clearing Fund Size To Include Consideration of the Amount Necessary To...

  14. eGSM: A extended Sky Model of Diffuse Radio Emission

    Science.gov (United States)

    Kim, Doyeon; Liu, Adrian; Switzer, Eric

    2018-01-01

    Both cosmic microwave background and 21cm cosmology observations must contend with astrophysical foreground contaminants in the form of diffuse radio emission. For precise cosmological measurements, these foregrounds must be accurately modeled over the entire sky Ideally, such full-sky models ought to be primarily motivated by observations. Yet in practice, these observations are limited, with data sets that are observed not only in a heterogenous fashion, but also over limited frequency ranges. Previously, the Global Sky Model (GSM) took some steps towards solving the problem of incomplete observational data by interpolating over multi-frequency maps using principal component analysis (PCA).In this poster, we present an extended version of GSM (called eGSM) that includes the following improvements: 1) better zero-level calibration 2) incorporation of non-uniform survey resolutions and sky coverage 3) the ability to quantify uncertainties in sky models 4) the ability to optimally select spectral models using Bayesian Evidence techniques.

  15. Open Skies and monitoring a fissile materials cut-off treaty

    International Nuclear Information System (INIS)

    Allentuck, J.; Lemley, J.R.

    1995-01-01

    The Treaty on Open Skies (Open Skies) is intended among other things to provide, in the words of its preamble, means ''to facilitate the monitoring of compliance with existing or future arms control agreements.'' Open Skies permits overflights of the territory of member states by aircraft equipped with an array of sensors of various types. Their types and capabilities are treaty-limited. To find useful application in monitoring a cut-off treaty Open Skies would need to be amended. The number of signatories would need to be expanded so as to provide greater geographical coverage, and restrictions on sensor-array capabilities would need to be relaxed. To facilitate the detection of impending violations of a cut-off convention by Open Skies overflights, the data base provided by parties to the former should include among other things an enumeration of existing and former fuel cycle and research facilities including those converted to other uses, their precise geographic location, and a site plan

  16. Measuring and mapping the night sky brightness of Perth, Western Australia

    Science.gov (United States)

    Biggs, James D.; Fouché, Tiffany; Bilki, Frank; Zadnik, Marjan G.

    2012-04-01

    In order to study the light pollution produced in the city of Perth, Western Australia, we have used a hand-held sky brightness meter to measure the night sky brightness across the city. The data acquired facilitated the creation of a contour map of night sky brightness across the 2400 km2 area of the city - the first such map to be produced for a city. Importantly, this map was created using a methodology borrowed from the field of geophysics - the well proven and rigorous techniques of geostatistical analysis and modelling. A major finding of this study is the effect of land use on night sky brightness. By overlaying the night sky brightness map on to a suitably processed Landsat satellite image of Perth we found that locations near commercial and/or light industrial areas have a brighter night sky, whereas locations used for agriculture or having high vegetation coverage have a fainter night sky than surrounding areas. Urban areas have intermediate amounts of vegetation and are intermediate in brightness compared with the above-mentioned land uses. Regions with a higher density of major highways also appear to contribute to increased night sky brightness. When corrected for the effects of direct illumination from high buildings, we found that the night sky brightness in the central business district (CBD) is very close to that expected for a city of Perth's population from modelling work and observations obtained in earlier studies. Given that our night sky brightness measurements in Perth over 2009 and 2010 are commensurate with that measured in Canadian cities over 30 years earlier implies that the various lighting systems employed in Perth (and probably most other cities) have not been optimised to minimize light pollution over that time. We also found that night sky brightness diminished with distance with an exponent of approximately -0.25 ± 0.02 from 3.5 to 10 km from the Perth CBD, a region characterized by urban and commercial land use. For distances

  17. NRAO Makes Available VLA Sky Survey Maps

    Science.gov (United States)

    1994-06-01

    An original and comprehensive data set potentially full of scientific surprises now is available to astronomers, students and the public through the information superhighway. Radio images of the sky produced by the Very Large Array radio telescope -- one of the premier astronomical instruments in the world -- as part of a massive survey now are stored in an electronic repository avail- able over the Internet computer communications network. "Each of these sensitive new sky maps shows about a thou- sand radio-emitting objects, most of which have never been seen before," said Dr. J. J. Condon, leader of the National Radio As- tronomy Observatory (NRAO) survey team. "We are releasing them as soon as they are completed because they contain more data than we could possibly analyze by ourselves." "By using electronic distribution, we can open this tre- mendous resource of information for computer analysis by all as- tronomers immediately, without waiting for traditional publication," Condon added. The radio images are copyright NRAO/ AUI. Permission is granted for use of the material without charge for scholarly, educational and private non-commercial purposes. "It is entirely conceivable -- even probable -- that valuable discoveries will be made by students or amateur astrono- mers who devote the time to study these maps carefully," said team member Dr. W. D. Cotton. "Making this new information available electronically means that more people can participate in adding to its scientific value." The maps are a product of the NRAO VLA Sky Survey (NVSS), which began its observational phase in September of 1993 and will cover 82 percent of the sky when completed by the end of 1996. The NVSS is expected to produce a catalog of more than two million ra- dio-emitting objects in the sky, and it is the first sky survey sensitive to linearly polarized emission from radio sources beyond our own Milky Way galaxy. "The NVSS is being made as a service to the entire astronomical

  18. 76 FR 72483 - Self-Regulatory Organizations; Options Clearing Corporation; Order Approving Proposed Rule Change...

    Science.gov (United States)

    2011-11-23

    ... existing interpretation, which relates to the treatment and clearing of options on the CBOE Gold ETF... jurisdictional status CBOE Gold ETF Volatility Index and clarifies that OCC will clear and treat as securities... relative performance index is an ETF designed to measure the return of gold [[Page 72484

  19. ESASky: All the sky you need

    Science.gov (United States)

    De Marchi, Guido; ESASky Team

    2018-06-01

    ESASky is a discovery portal giving to all astronomers, professional and amateur alike, an easy way to access high-quality scientific data from their computer, tablet, or mobile device. It includes over half a million images, 300,000 spectra, and more than a billion catalogue sources. From gamma rays to radio wavelengths, it allows users to explore the cosmos with data from a dozen space missions from the astronomical archives of ESA, NASA, and JAXA and does not require prior knowledge of any particular mission. ESASky features an all-sky exploration interface, letting users easily zoom in for stars as single targets or as part of a whole galaxy, visualise them and retrieve the relevant data taken in an area of the sky with just a few clicks. Users can easily compare observations of the same source obtained by different space missions at different times and wavelengths. They can also use ESASky to plan future observations with the James Webb Space Telescope, comparing the relevant portion of the sky as observed by Hubble and other missions. We will illustrate the many options to visualise and access astronomical data: interactive footprints for each instrument, tree-maps, filters, and solar-system object trajectories can all be combined and displayed. The most recent version of ESASky, released in February, also includes access to scientific publications, allowing users to visualise on the sky all astronomical objects with associated scientific publications and to link directly back to the papers in the NASA Astrophysics Data System.

  20. The Impact of Cross-track Infrared Sounder (CrIS) Cloud-Cleared Radiances on Hurricane Joaquin (2015) and Matthew (2016) Forecasts

    Science.gov (United States)

    Wang, Pei; Li, Jun; Li, Zhenglong; Lim, Agnes H. N.; Li, Jinlong; Schmit, Timothy J.; Goldberg, Mitchell D.

    2017-12-01

    Hyperspectral infrared (IR) sounders provide high vertical resolution atmospheric sounding information that can improve the forecast skill in numerical weather prediction. Commonly, only clear radiances are assimilated, because IR sounder observations are highly affected by clouds. A cloud-clearing (CC) technique, which removes the cloud effects from an IR cloudy field of view (FOV) and derives the cloud-cleared radiances (CCRs) or clear-sky equivalent radiances, can be an alternative yet effective way to take advantage of the thermodynamic information from cloudy skies in data assimilation. This study develops a Visible Infrared Imaging Radiometer Suite (VIIRS)-based CC method for deriving Cross-track Infrared Sounder (CrIS) CCRs under partially cloudy conditions. Due to the lack of absorption bands on VIIRS, two important quality control steps are implemented in the CC process. Validation using VIIRS clear radiances indicates that the CC method can effectively obtain the CrIS CCRs for FOVs with partial cloud cover. To compare the impacts from assimilation of CrIS original radiances and CCRs, three experiments are carried out on two storm cases, Hurricane Joaquin (2015) and Hurricane Matthew (2016), using Gridpoint Statistical Interpolation assimilation system and Weather Research and Forecasting-Advanced Research Version models. At the analysis time, more CrIS observations are assimilated when using CrIS CCRs than with CrIS original radiances. Comparing temperature, specific humidity, and U/V winds with radiosondes indicates that the data impacts are growing larger with longer time forecasts (beyond 72 h forecast). Hurricane track forecasts also show improvements from the assimilation of CrIS CCRs due to better weather system forecasts. The impacts of CCRs on intensity are basically neutral with mixed positive and negative results.

  1. A comet's tale: How much of the world came to miss the most spectacular sky spectacle in decades

    Science.gov (United States)

    Fischer, D.

    2008-06-01

    In January 2007 comet C/2006 P1, named McNaught, became brighter than Venus, was visible in the daytime sky and developed the most dramatic dust tail in recent memory. For those with clear skies during the crucial days and in the right geographical latitudes it was a sight to remember, a subject of everyday conversation, gaining local presence in the general media as well. But the world's media at large practically ignored what was literally the greatest astronomical story in decades, except in regional markets. This paper traces the surprising failure of the early 21st century media machinery to several interrelated factors and concludes that there was simply `no one in charge' at the crucial moments. Finally, the case of comet 17P/Holmes - which increased its brightness a million times two weeks after CAP2007 - is treated as a complementary case study in progress.

  2. Direct Aerosol Radiative Forcing from Combined A-Train Observations - Preliminary Comparisons with AeroCom Models and Pathways to Observationally Based All-sky Estimates

    Science.gov (United States)

    Redemann, J.; Livingston, J. M.; Shinozuka, Y.; Kacenelenbogen, M. S.; Russell, P. B.; LeBlanc, S. E.; Vaughan, M.; Ferrare, R. A.; Hostetler, C. A.; Rogers, R. R.; Burton, S. P.; Torres, O.; Remer, L. A.; Stier, P.; Schutgens, N.

    2014-12-01

    We describe a technique for combining CALIOP aerosol backscatter, MODIS spectral AOD (aerosol optical depth), and OMI AAOD (absorption aerosol optical depth) retrievals for the purpose of estimating full spectral sets of aerosol radiative properties, and ultimately for calculating the 3-D distribution of direct aerosol radiative forcing. We present results using one year of data collected in 2007 and show comparisons of the aerosol radiative property estimates to collocated AERONET retrievals. Use of the recently released MODIS Collection 6 data for aerosol optical depths derived with the dark target and deep blue algorithms has extended the coverage of the multi-sensor estimates towards higher latitudes. Initial calculations of seasonal clear-sky aerosol radiative forcing based on our multi-sensor aerosol retrievals compare well with over-ocean and top of the atmosphere IPCC-2007 model-based results, and with more recent assessments in the "Climate Change Science Program Report: Atmospheric Aerosol Properties and Climate Impacts" (2009). For the first time, we present comparisons of our multi-sensor aerosol direct radiative forcing estimates to values derived from a subset of models that participated in the latest AeroCom initiative. We discuss the major challenges that exist in extending our clear-sky results to all-sky conditions. On the basis of comparisons to suborbital measurements, we present some of the limitations of the MODIS and CALIOP retrievals in the presence of adjacent or underlying clouds. Strategies for meeting these challenges are discussed.

  3. Predicting daylight illuminance on inclined surfaces using sky luminance data

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.H.W.; Lau, C.C.S.; Lam, J.C. [City University of Hong Kong, Kowloon (China). Dept. of Building and Construction

    2005-07-01

    Daylight illuminance, particularly on vertical surfaces, plays a major role in determining and evaluating the daylighting performance of a building. In many parts of the world, however, the basic daylight illuminance data for various vertical planes are not always readily available. The usual method to obtain diffuse illuminance on tilted planes would be based on inclined surface models using data from the horizontal measurements. Alternatively, the diffuse illuminance on a sloping plane can be computed by integrating the luminance distribution of the sky 'seen' by the plane. This paper presents an approach to estimate the vertical outdoor illuminance from sky luminance data and solar geometry. Sky luminance data recorded from January 1999 to December 2001 in Hong Kong and generated by two well-known sky luminance models (Kittler and Perez) were used to compute the outdoor illuminance for the four principal vertical planes (N, E, S and W). The performance of this approach was evaluated against data measured in the same period. Statistical analysis indicated that using sky luminance distributions to predict outdoor illuminance can give reasonably good agreement with measured data for all vertical surfaces. The findings provide an accurate alternative to determine the amount of daylight on vertical as well as other inclined surfaces when sky luminance data are available. (author)

  4. Tropical rainforest response to marine sky brightening climate engineering

    Science.gov (United States)

    Muri, Helene; Niemeier, Ulrike; Kristjánsson, Jón Egill

    2015-04-01

    Tropical forests represent a major atmospheric carbon dioxide sink. Here the gross primary productivity (GPP) response of tropical rainforests to climate engineering via marine sky brightening under a future scenario is investigated in three Earth system models. The model response is diverse, and in two of the three models, the tropical GPP shows a decrease from the marine sky brightening climate engineering. Partial correlation analysis indicates precipitation to be important in one of those models, while precipitation and temperature are limiting factors in the other. One model experiences a reversal of its Amazon dieback under marine sky brightening. There, the strongest partial correlation of GPP is to temperature and incoming solar radiation at the surface. Carbon fertilization provides a higher future tropical rainforest GPP overall, both with and without climate engineering. Salt damage to plants and soils could be an important aspect of marine sky brightening.

  5. The observer's sky atlas

    CERN Document Server

    Karkoschka, E

    2007-01-01

    This title includes a short introduction to observing, a thorough description of the star charts and tables, a glossary and much more. It is perfect for both the beginner and seasoned observer. It is fully revised edition of a best-selling and highly-praised sky atlas.

  6. Scattering of Light by Colloidal Aluminosilicate Particles Produces the Unusual Sky-Blue Color of R?o Celeste (Tenorio Volcano Complex, Costa Rica)

    OpenAIRE

    Castell?n, Erick; Mart?nez, Mar?a; Madrigal-Carballo, Sergio; Arias, Mar?a Laura; Vargas, William E.; Chavarr?a, Max

    2013-01-01

    Río Celeste (Sky-Blue River) in Tenorio National Park (Costa Rica), a river that derives from the confluence and mixing of two colorless streams--Río Buenavista (Buenavista River) and Quebrada Agria (Sour Creek)--is renowned in Costa Rica because it presents an atypical intense sky-blue color. Although various explanations have been proposed for this unusual hue of Río Celeste, no exhaustive tests have been undertaken; the reasons hence remain unclear. To understand this color phenomenon, we ...

  7. Sun, Earth and Sky

    CERN Document Server

    Lang, Kenneth R

    2006-01-01

    This Second Edition of Sun, Earth and Sky updates the popular text by providing comprehensive accounts of the most recent discoveries made by five modern solar spacecraft during the past decade. Their instruments have used sound waves to peer deep into the Sun’s inner regions and measure the temperature of its central nuclear reactor, and extended our gaze far from the visible Sun to record energetic outbursts that threaten Earth. Breakthrough observations with the underground Sudbury Neutrino Observatory are also included, which explain the new physics of ghostly neutrinos and solve the problematic mismatch between the predicted and observed amounts of solar neutrinos. This new edition of Sun, Earth and Sky also describes our recent understanding of how the Sun’s outer atmosphere is heated to a million degrees, and just where the Sun’s continuous winds come from. As humans we are more intimately linked with our life-sustaining Sun than with any other astronomical object, and the new edition therefore p...

  8. Observations of temporal change of nighttime cloud cover from Himawari 8 and ground-based sky camera over Chiba, Japan

    Science.gov (United States)

    Lagrosas, N.; Gacal, G. F. B.; Kuze, H.

    2017-12-01

    Detection of nighttime cloud from Himawari 8 is implemented using the difference of digital numbers from bands 13 (10.4µm) and 7 (3.9µm). The digital number difference of -1.39x104 can be used as a threshold to separate clouds from clear sky conditions. To look at observations from the ground over Chiba, a digital camera (Canon Powershot A2300) is used to take images of the sky every 5 minutes at an exposure time of 5s at the Center for Environmental Remote Sensing, Chiba University. From these images, cloud cover values are obtained using threshold algorithm (Gacal, et al, 2016). Ten minute nighttime cloud cover values from these two datasets are compared and analyzed from 29 May to 05 June 2017 (20:00-03:00 JST). When compared with lidar data, the camera can detect thick high level clouds up to 10km. The results show that during clear sky conditions (02-03 June), both camera and satellite cloud cover values show 0% cloud cover. During cloudy conditions (05-06 June), the camera shows almost 100% cloud cover while satellite cloud cover values range from 60 to 100%. These low values can be attributed to the presence of low-level thin clouds ( 2km above the ground) as observed from National Institute for Environmental Studies lidar located inside Chiba University. This difference of cloud cover values shows that the camera can produce accurate cloud cover values of low level clouds that are sometimes not detected by satellites. The opposite occurs when high level clouds are present (01-02 June). Derived satellite cloud cover shows almost 100% during the whole night while ground-based camera shows cloud cover values that range from 10 to 100% during the same time interval. The fluctuating values can be attributed to the presence of thin clouds located at around 6km from the ground and the presence of low level clouds ( 1km). Since the camera relies on the reflected city lights, it is possible that the high level thin clouds are not observed by the camera but is

  9. Introduction to the Arizona Sky Island Arthropod Project (ASAP): Systematics, biogeography, ecology, and population genetics of arthropods of the Madrean Sky Islands

    Science.gov (United States)

    Wendy Moore; Wallace M. Meyer; Jeffrey A. Eble; Kimberly Franklin; John F. Wiens; Richard C. Brusca

    2013-01-01

    The Arizona Sky Island Arthropod Project (ASAP) is a new multi-disciplinary research program at the University of Arizona that combines systematics, biogeography, ecology, and population genetics to study origins and patterns of arthropod diversity along elevation gradients and among mountain ranges in the Madrean Sky Island Region. Arthropods represent taxonomically...

  10. Sky shine of proton synchrotron

    International Nuclear Information System (INIS)

    Katoh, Kazuaki; Hirayama, Hideo

    1978-01-01

    This report represents present status of the study on sky shine and the results made at KEK. At present, data at various facilities can be analyzed by the formula presented by R.H. Thomas. Measurement of sky shine at KEK has been carried out since August, 1977. The neutron level around the accelerator, spatial distribution, energy spectra and the intensities at far distant places were measured. The radiation level at the surface of shield of the accelerator is less than 0.8 mrem/h. Therefore, high sensitive detectors are required to measure the neutron at the far distant places. A 2 inch diameter BF 3 detector with polyethylene moderator and a 5.8 inch diameter BF 3 detector with same moderator were used for the measurement. Conversion from the obtained counting rate to the dose rate was made by using the conversion coefficient for fission neutrons of Cf-252. The dose rate distributions at the shielding surface of the main ring of the accelerator and the counter experiment hall were measured. At the main ring, the dose rate was less than 0.16 mrem/h, and at the counter hall the maximum dose rate was 5 mrem/h. The distance dependence of the sky shine level was measured, and the effective attenuation distance was 1300 m. The result can be expressed by the formula by Thomas. (Kato, T.)

  11. Dark Skies Awareness Programs for the U.S. International Year of Astronomy

    Science.gov (United States)

    Walker, Constance E.; U. S. IYA Dark Skies Working Group

    2009-01-01

    The loss of a dark night sky as a natural resource is a growing concern. It impacts not only astronomical research, but also our ecology, health, safety, economics and energy conservation. For this reason, "Dark Skies are a Universal Resource” is one of seven primary themes of the U.S. International Year of Astronomy program in 2009. Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people involved in a variety of dark skies-related programs. To reach this goal, activities have been developed that: 1) Teach about dark skies using new technology (e.g., an activity-based planetarium show on DVD, podcasting, social networking, Second Life) 2) Provide thematic events on light pollution at star parties and observatory open houses (Dark Skies Discovery Sites, Astronomy Nights in the (National) Parks, Sidewalk Astronomy Nights) 3) Organize an event in the arts (e.g., a photography contest) 4) Involve citizen-scientists in unaided-eye and digital-meter star counting programs, as well as RFI monitoring (e.g., GLOBE at Night and Quiet Skies) and 5) Raise awareness about the link between light pollution and public health, economic issues, ecological consequences, energy conservation, safety and security (e.g., the Dark Skies Toolkit, Good Neighbor Lighting, Earth Hour, National Dark Skies Week, traveling exhibits and a 6-minute video tutorial). To deliver these programs, strategic networks have been established with astronomy clubs (ASP's Night Sky Network's astronomy clubs and the Astronomical League), science and nature centers (Astronomy from the Ground Up and the Association of Science and Technology), educational programs (Project ASTRO and GLOBE) and the International Dark-sky Association. The poster will describe the "know-how” and the means for people to become community advocates in promoting Dark Skies programs as public events at their home institutions. For more information, visit http://astronomy2009

  12. Instrumentation for comparing night sky quality and atmospheric conditions of CTA site candidates

    International Nuclear Information System (INIS)

    Fruck, C.; Schweizer, T.; Häfner, D.; Lorentz, E.; Teshima, M.; Gaug, M.; Ernenwein, J.-P.; Costantini, H.; Mandát, D.; Pech, M.; Bulik, T.; Cieslar, M.; Dominik, M.; Ebr, J.; Garczarczyk, M.; Pareschi, G.; Puerto-Giménez, I.

    2015-01-01

    Many atmospheric and climatic criteria have to be taken into account for the selection of a suitable site for the next generation of imaging air-shower Cherenkov telescopes, the ''Cherenkov Telescope Array'' CTA. Such data are not available with sufficient precision, thus a comparison of the proposed sites and final decision based on a comprehensive characterization is impossible. Identical cross-calibrated instruments have been developed which allow for precise comparison between sites, the cross-validation of existing data, and the ground-validation of satellite data. The site characterization work package of the CTA consortium opted to construct and deploy 9 copies of an autonomous multi-purpose weather sensor, incorporating an infrared cloud sensor, a newly developed sensor for measuring the light of the night sky, and an All-Sky-Camera, the whole referred to as Autonomous Tool for Measuring Observatory Site COnditions PrEcisely (ATMOSCOPE). We present here the hardware that was combined into the ATMOSCOPE and characterize its performance

  13. The new world atlas of artificial night sky brightness.

    Science.gov (United States)

    Falchi, Fabio; Cinzano, Pierantonio; Duriscoe, Dan; Kyba, Christopher C M; Elvidge, Christopher D; Baugh, Kimberly; Portnov, Boris A; Rybnikova, Nataliya A; Furgoni, Riccardo

    2016-06-01

    Artificial lights raise night sky luminance, creating the most visible effect of light pollution-artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world's land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights.

  14. Using All-Sky Imaging to Improve Telescope Scheduling (Abstract)

    Science.gov (United States)

    Cole, G. M.

    2017-12-01

    (Abstract only) Automated scheduling makes it possible for a small telescope to observe a large number of targets in a single night. But when used in areas which have less-than-perfect sky conditions such automation can lead to large numbers of observations of clouds and haze. This paper describes the development of a "sky-aware" telescope automation system that integrates the data flow from an SBIG AllSky340c camera with an enhanced dispatch scheduler to make optimum use of the available observing conditions for two highly instrumented backyard telescopes. Using the minute-by-minute time series image stream and a self-maintained reference database, the software maintains a file of sky brightness, transparency, stability, and forecasted visibility at several hundred grid positions. The scheduling software uses this information in real time to exclude targets obscured by clouds and select the best observing task, taking into account the requirements and limits of each instrument.

  15. Secrets to Successful Earth and Sky Photography

    Science.gov (United States)

    Tafreshi, Babak A.

    In the absolute silence of a desert night, surrounded by an arena of celestial beauties, a gentle breeze shifts the tiny grains of sand around me. There is a patchy glow of light visible all across the eastern horizon. It is gradually ascending over the sand dunes. The glow represents billions of stars in our home galaxy rising above the horizon of our planet. I have seen such dream-like starry scenes from many locations; from the boundless dark skies of the African Sahara when the summer Milky Way was arching over giant sandstones, to the shimmering beauty of the Grand Canyon under moonlight, and the transparent skies of the Himalayas when the bright stars of winter were rising above where the highest peak on Earth (Mt. Everest) meets the sky. These are forever-engraved moments in my memory. Astrophotography is not only about recording the celestial world. It can lead you to a life of adventure and discovery (Fig. 1).

  16. A New Sky Brightness Monitor

    Science.gov (United States)

    Crawford, David L.; McKenna, D.

    2006-12-01

    A good estimate of sky brightness and its variations throughout the night, the months, and even the years is an essential bit of knowledge both for good observing and especially as a tool in efforts to minimize sky brightness through local action. Hence a stable and accurate monitor can be a valuable and necessary tool. We have developed such a monitor, with the financial help of Vatican Observatory and Walker Management. The device is now undergoing its Beta test in preparation for production. It is simple, accurate, well calibrated, and automatic, sending its data directly to IDA over the internet via E-mail . Approximately 50 such monitors will be ready soon for deployment worldwide including most major observatories. Those interested in having one should enquire of IDA about details.

  17. A new technique for measuring aerosols with moonlight observations and a sky background model

    Science.gov (United States)

    Jones, Amy; Noll, Stefan; Kausch, Wolfgang; Kimeswenger, Stefan; Szyszka, Ceszary; Unterguggenberger, Stefanie

    2014-05-01

    There have been an ample number of studies on aerosols in urban, daylight conditions, but few for remote, nocturnal aerosols. We have developed a new technique for investigating such aerosols using our sky background model and astronomical observations. With a dedicated observing proposal we have successfully tested this technique for nocturnal, remote aerosol studies. This technique relies on three requirements: (a) sky background model, (b) observations taken with scattered moonlight, and (c) spectrophotometric standard star observations for flux calibrations. The sky background model was developed for the European Southern Observatory and is optimized for the Very Large Telescope at Cerro Paranal in the Atacama desert in Chile. This is a remote location with almost no urban aerosols. It is well suited for studying remote background aerosols that are normally difficult to detect. Our sky background model has an uncertainty of around 20 percent and the scattered moonlight portion is even more accurate. The last two requirements are having astronomical observations with moonlight and of standard stars at different airmasses, all during the same night. We had a dedicated observing proposal at Cerro Paranal with the instrument X-Shooter to use as a case study for this method. X-Shooter is a medium resolution, echelle spectrograph which covers the wavelengths from 0.3 to 2.5 micrometers. We observed plain sky at six different distances (7, 13, 20, 45, 90, and 110 degrees) to the Moon for three different Moon phases (between full and half). Also direct observations of spectrophotometric standard stars were taken at two different airmasses for each night to measure the extinction curve via the Langley method. This is an ideal data set for testing this technique. The underlying assumption is that all components, other than the atmospheric conditions (specifically aerosols and airglow), can be calculated with the model for the given observing parameters. The scattered

  18. Gaia, an all-sky survey for standard photometry

    Science.gov (United States)

    Carrasco, J. M.; Weiler, M.; Jordi, C.; Fabricius, C.

    2017-03-01

    Gaia ESA's space mission (launched in 2013) includes two low resolution spectroscopic instruments (one in the blue, BP, and another in the red, RP, wavelength domains) to classify and derive the astrophysical parameters of the observed sources. As it is well known, Gaia is a full-sky unbiased survey down to about 20th magnitude. The scanning law yields a rather uniform coverage of the sky over the full extent (a minimum of 5 years) of the mission. Gaia data reduction is a global one over the full mission. Both sky coverage and data reduction strategy ensure an unprecedented all-sky homogeneous spectrophotometric survey. Certainly, that survey is of interest for current and future on-ground and space projects, like LSST, PLATO, EUCLID and J-PAS/J-PLUS among others. These projects will benefit from the large amount (more than one billion) and wide variety of objects observed by Gaia with good quality spectrophotometry. Synthetic photometry derived from Gaia spectrophotometry for any passband can be used to expand the set of standard sources for these new instruments to come. In the current Gaia data release scenario, BP/RP spectrophotometric data will be available in the third release (in 2018, TBC). Current preliminary results allow us to estimate the precision of synthetic photometry derived from the Gaia data. This already allows the preparation of the on-going and future surveys and space missions. We discuss here the exploitation of the Gaia spectrophotometry as standard reference due to its full-sky coverage and its expected photometric uncertainties derived from the low resolution Gaia spectra.

  19. Artificial light alters natural regimes of night-time sky brightness

    Science.gov (United States)

    Davies, Thomas W.; Bennie, Jonathan; Inger, Richard; Gaston, Kevin J.

    2013-01-01

    Artificial light is globally one of the most widely distributed forms of anthropogenic pollution. However, while both the nature and ecological effects of direct artificial lighting are increasingly well documented, those of artificial sky glow have received little attention. We investigated how city lights alter natural regimes of lunar sky brightness using a novel ten month time series of measurements recorded across a gradient of increasing light pollution. In the city, artificial lights increased sky brightness to levels six times above those recorded in rural locations, nine and twenty kilometers away. Artificial lighting masked natural monthly and seasonal regimes of lunar sky brightness in the city, and increased the number and annual regime of full moon equivalent hours available to organisms during the night. The changes have potentially profound ecological consequences.

  20. VizieR Online Data Catalog: Northern Sky Variability Survey (Wozniak+, 2004)

    Science.gov (United States)

    Wozniak, P. R.; Vestrand, W. T.; Akerlof, C. W.; Balsano, R.; Bloch, J.; Casperson, D.; Fletcher, S.; Gisler, G.; Kehoe, R.; Kinemuchi, K.; Lee, B. C.; Marshall, S.; McGowan, K. E.; McKay, T. A.; Rykoff, E. S.; Smith, D. A.; Szymanski, J.; Wren, J.

    2004-11-01

    The Northern Sky Variability Survey (NSVS) is a temporal record of the sky over the optical magnitude range from 8 to 15.5. It was conducted in the course of the first-generation Robotic Optical Transient Search Experiment (ROTSE-I) using a robotic system of four comounted unfiltered telephoto lenses equipped with CCD cameras. The survey was conducted from Los Alamos, New Mexico, and primarily covers the entire northern sky. Some data in southern fields between declinations 0{deg} and -38{deg} are also available, although with fewer epochs and noticeably lesser quality. The NSVS contains light curves for approximately 14 million objects. With a 1-yr baseline and typically 100-500 measurements per object, the NSVS is the most extensive record of stellar variability across the bright sky available today. In a median field, bright unsaturated stars attain a point-to-point photometric scatter of ~0.02mag and position errors within 2. At Galactic latitudes |b|public access from the Sky Database for Objects in Time-Domain (SkyDOT) at Los Alamos National Laboratory. Copies of the full survey photometry may also be requested on tape. (7 data files).

  1. Observation of the Spectrally Invariant Properties of Clouds in Cloudy-to-Clear Transition Zones During the MAGIC Field Campaign

    Science.gov (United States)

    Yang, Weidong; Marshak, Alexander; McBride, Patrick; Chiu, J. Christine; Knyazikhin, Yuri; Schmidt, K. Sebastian; Flynn, Connor; Lewis, Ernie R.; Eloranta, Edwin W.

    2016-01-01

    We use the spectrally invariant method to study the variability of cloud optical thickness tau and droplet effective radius r(sub eff) in transition zones (between the cloudy and clear sky columns) observed from Solar Spectral Flux Radiometer (SSFR) and Shortwave Array Spectroradiometer-Zenith (SASZe) during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The measurements from the SSFR and the SASZe are different, however inter-instrument differences of self-normalized measurements (divided by their own spectra at a fixed time) are small. The spectrally invariant method approximates the spectra in the cloud transition zone as a linear combination of definitely clear and cloudy spectra, where the coefficients, slope and intercept, characterize the spectrally invariant properties of the transition zone. Simulation results from the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model demonstrate that (1) the slope of the visible band is positively correlated with the cloud optical thickness t while the intercept of the near-infrared band has high negative correlation with the cloud drop effective radius r(sub eff)even without the exact knowledge of tau; (2) the above relations hold for all Solar Zenith Angle (SZA) and for cloud-contaminated skies. In observations using redundant measurements from SSFR and SASZe, we find that during cloudy-to-clear transitions, (a) the slopes of the visible band decrease, and (b) the intercepts of the near-infrared band remain almost constant near cloud edges. The findings in simulations and observations suggest that, while the optical thickness decreases during the cloudy-to-clear transition, the cloud drop effective radius does not change when cloud edges are approached. These results support the hypothesis that inhomogeneous mixing dominates near cloud edges in the studied cases.

  2. Pi of the Sky Telescopes in Spain and Chile

    Directory of Open Access Journals (Sweden)

    M. Siudek

    2011-01-01

    Full Text Available Pi of the Sky is a system of robotic telescopes designed for observations of short timescale astrophysical phenomena, e.g. prompt optical GRB emissions. The apparatus is designed to monitor a large fraction of the sky with 12–13 m range and time resolution of the order of 1–10 seconds. In October 2010 the first unit of the new Pi of the Sky detector system was successfully installed in the INTA El Arenosillo Test Centre in Spain. We also moved our prototype detector from Las Campanas Observatory to San Pedro de Atacama Observatory in March 2011. The status and performance of both detectors is presented.

  3. 75 FR 77576 - General Regulations and Derivatives Clearing Organizations

    Science.gov (United States)

    2010-12-13

    ... Derivatives Clearing Organizations AGENCY: Commodity Futures Trading Commission. ACTION: Notice of proposed... derivatives clearing organization (DCO) Core Principles A (Compliance), H (Rule Enforcement), N (Antitrust... commission merchant (FCM) that is also registered as a securities broker-dealer (FCM/BD), and make certain...

  4. Estimation of spectral solar radiation based on global insolation and characteristics of spectral solar radiation on a tilt surface; Zenten nissharyo ni motozuku zenten nissha supekutoru no suitei to keishamen bunko tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Baba, H; Kanayama, K; Endo, N; Koromohara, K; Takayama, H [Kitami Institute of Technology, Hokkaido (Japan)

    1996-10-27

    Use of global insolation for estimating the corresponding spectral distribution is proposed. Measurements of global insolation spectrum throughout a year were compiled for clear days and cloudy days, ranked by 100W/m{sup 2}, for the clarification of spectral distribution. Global insolation quantity for a clear day was subject mainly to sun elevation. The global insolation spectral distribution with the sun elevation not lower than 15{degree} was similar to Bird`s model. Under the cloudy sky, energy density was lower in the region of wavelengths longer than the peak wavelength of 0.46{mu}m, and the distribution curve was sharper than that under the clear sky. Values given by Bird`s model were larger than measured values in the wavelength range of 0.6-1.8{mu}m, which was attributed to absorption by vapor. From the standard spectral distribution charts for the clear sky and cloudy sky, and from the dimensionless spectral distributions obtained by dividing them by the peak values, spectral distributions could be estimated of insolation quantities for the clear sky, cloudy sky, etc. As for the characteristics of spectral solar radiation on a tilt surface obtained from Bird`s model, they agreed with actually measured values at an angle of inclination of 60{degree} or smaller. 6 refs., 10 figs., 1 tab.

  5. Deep-Sky Video Astronomy

    CERN Document Server

    Massey, Steve

    2009-01-01

    A guide to using modern integrating video cameras for deep-sky viewing and imaging with the kinds of modest telescopes available commercially to amateur astronomers. It includes an introduction and a brief history of the technology and camera types. It examines the pros and cons of this unrefrigerated yet highly efficient technology

  6. Automated Meteor Detection by All-Sky Digital Camera Systems

    Science.gov (United States)

    Suk, Tomáš; Šimberová, Stanislava

    2017-12-01

    We have developed a set of methods to detect meteor light traces captured by all-sky CCD cameras. Operating at small automatic observatories (stations), these cameras create a network spread over a large territory. Image data coming from these stations are merged in one central node. Since a vast amount of data is collected by the stations in a single night, robotic storage and analysis are essential to processing. The proposed methodology is adapted to data from a network of automatic stations equipped with digital fish-eye cameras and includes data capturing, preparation, pre-processing, analysis, and finally recognition of objects in time sequences. In our experiments we utilized real observed data from two stations.

  7. 76 FR 42704 - Sky River LLC; Notice of Filing

    Science.gov (United States)

    2011-07-19

    ... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket Nos. ER11-3277-000; ER11-3277-001] Sky River LLC; Notice of Filing Take notice that, on July 8, 2011, Sky River LLC filed to amend its Open Access Transmission Tariff (OATT) filing, submitted on April 1, 2011 and amended on April 7...

  8. Gender Roles and Night-Sky Watching among College Students

    Science.gov (United States)

    Kelly, William E.; McGee, Catherine M.

    2012-01-01

    The present study investigated the relationship between gender roles and night-sky watching in a sample of college students (N=161). The Bem Sex-Role Inventory (BSRI) and the Noctcaelador Inventory (NI) were used to investigate the differences between gender role groups for night-sky watching. The results supported the hypothesis that androgynous…

  9. VizieR Online Data Catalog: The VLA Low-frequency Sky Survey at 74MHz (Perley+ 2006)

    Science.gov (United States)

    Perley, R. A.; Condon, J. J.; Cotton, W. D.; Cohen, A. S.; Lane, W. M.; Kassim, N. E.; Lazio, T. J. W.; Erickson, W. C.

    2006-08-01

    The VLA Low-Frequency Sky Survey (VLSS) is a 74MHz (4m) continuum survey covering the entire sky north of -30{deg} declination. Using the VLA in B- and BnA-configurations, we will map the entire survey region at a resolution of 80" and with an average rms noise of 0.1 Jy/beam. For a detailed description of the survey and its scientific motivations, please see the original proposal to the NRAO skeptical review committee. The VLSS is being made as a service to the astronomical community, and the principal data products are being released to the public as soon as they are produced and verified. Details and access to the images can be found at http://lwa.nrl.navy.mil/VLSS/ (1 data file).

  10. VizieR Online Data Catalog: The VLA Low-frequency Sky Survey at 74MHz (Cohen+ 2007)

    Science.gov (United States)

    Cohen, A. S.; Lane, W. M.; Cotton, W. D.; Kassim, N. E.; Lazio, T. J. W.; Perley, R. A.; Condon, J. J.; Erickson, W. C.

    2006-08-01

    The VLA Low-Frequency Sky Survey (VLSS) is a 74MHz (4m) continuum survey covering the entire sky north of -30{deg} declination. Using the VLA in B- and BnA-configurations, we will map the entire survey region at a resolution of 80" and with an average rms noise of 0.1 Jy/beam. For a detailed description of the survey and its scientific motivations, please see the original proposal to the NRAO skeptical review committee. The VLSS is being made as a service to the astronomical community, and the principal data products are being released to the public as soon as they are produced and verified. Details and access to the images can be found at http://lwa.nrl.navy.mil/VLSS/ (1 data file).

  11. Proposal for a project agreement with ISTC - Crystal Clear Collaboration

    CERN Document Server

    2001-01-01

    This document concerns a project agreement with the ISTC entitled "Development of the Detector Production Technology for a New Generation of Positron Emission Tomographs to be used in Medecine and Pharmacology" to be executed in co-operation with the Crystal Clear Collaboration. For the reasons set out in this document, the Finance Committee is invited to agree to the negotiation of a project agreement with ISTC for a total amount of 775 000 US dollars. The European Union party in ISTC will co-fund the project up to a total of 525 000 US dollars. CERN's contribution will not exceed 250 000 US dollars. At the present rate of exchange this is equivalent to approximately 430 000 Swiss francs

  12. The Big Sky inside

    Science.gov (United States)

    Adams, Earle; Ward, Tony J.; Vanek, Diana; Marra, Nancy; Hester, Carolyn; Knuth, Randy; Spangler, Todd; Jones, David; Henthorn, Melissa; Hammill, Brock; Smith, Paul; Salisbury, Rob; Reckin, Gene; Boulafentis, Johna

    2009-01-01

    The University of Montana (UM)-Missoula has implemented a problem-based program in which students perform scientific research focused on indoor air pollution. The Air Toxics Under the Big Sky program (Jones et al. 2007; Adams et al. 2008; Ward et al. 2008) provides a community-based framework for understanding the complex relationship between poor…

  13. 77 FR 27254 - Self-Regulatory Organizations; ICE Clear Europe Limited; Order Approving Proposed Rule Change To...

    Science.gov (United States)

    2012-05-09

    ... respect of the Clearing Member's Proprietary Account and any relevant customer account. Where the Daily...\\ requires, among other things, that the rules of a clearing agency be designed to promote the safeguarding... safeguarding of securities and funds, which are in the custody or control of ICE Clear Europe or for which it...

  14. Gods, Demons and Deceivers: Jesuits Facing Chaco Skies

    Science.gov (United States)

    López, Alejandro Martín

    2015-05-01

    The Jesuit missions located in the Chaco are less known than the ones in Paraguay. They are the last step of the Jesuits' missionary device in the Rio de la Plata region. They were dedicated to 'evangelize' and 'civilize' the aboriginal groups considered more hostile: nomadic hunter-gatherers who adopted the use of horses and were not controlled by the colonial government. These groups were seen by Europeans as a radical otherness. That is why the Jesuits' descriptions of Chaco Indian skies are a very interesting example about European attitudes toward other worldviews. This paper explores the use of different paradigms for interpreting these alternative skies: demonic influence, the deception of sorcerers and an Evemeristic reading of the indigenous worldview. This article also addresses some of the interactions between the aboriginal and Christian skies in the mission context.

  15. SkyMapper Southern Survey: First Data Release (DR1)

    Science.gov (United States)

    Wolf, Christian; Onken, Christopher A.; Luvaul, Lance C.; Schmidt, Brian P.; Bessell, Michael S.; Chang, Seo-Won; Da Costa, Gary S.; Mackey, Dougal; Martin-Jones, Tony; Murphy, Simon J.; Preston, Tim; Scalzo, Richard A.; Shao, Li; Smillie, Jon; Tisserand, Patrick; White, Marc C.; Yuan, Fang

    2018-02-01

    We present the first data release of the SkyMapper Southern Survey, a hemispheric survey carried out with the SkyMapper Telescope at Siding Spring Observatory in Australia. Here, we present the survey strategy, data processing, catalogue construction, and database schema. The first data release dataset includes over 66 000 images from the Shallow Survey component, covering an area of 17 200 deg2 in all six SkyMapper passbands uvgriz, while the full area covered by any passband exceeds 20 000 deg2. The catalogues contain over 285 million unique astrophysical objects, complete to roughly 18 mag in all bands. We compare our griz point-source photometry with Pan-STARRS1 first data release and note an RMS scatter of 2%. The internal reproducibility of SkyMapper photometry is on the order of 1%. Astrometric precision is better than 0.2 arcsec based on comparison with Gaia first data release. We describe the end-user database, through which data are presented to the world community, and provide some illustrative science queries.

  16. Proof of Concept for a Simple Smartphone Sky Monitor

    Science.gov (United States)

    Kantamneni, Abhilash; Nemiroff, R. J.; Brisbois, C.

    2013-01-01

    We present a novel approach of obtaining a cloud and bright sky monitor by using a standard smartphone with a downloadable app. The addition of an inexpensive fisheye lens can extend the angular range to the entire sky visible above the device. A preliminary proof of concept image shows an optical limit of about visual magnitude 5 for a 70-second exposure. Support science objectives include cloud monitoring in a manner similar to the more expensive cloud monitors in use at most major astronomical observatories, making expensive observing time at these observatories more efficient. Primary science objectives include bright meteor tracking, bright comet tracking, and monitoring the variability of bright stars. Citizen science objectives include crowd sourcing of many networked sky monitoring smartphones typically in broader support of many of the primary science goals. The deployment of a citizen smartphone array in an active science mode could leverage the sky monitoring data infrastructure to track other non-visual science opportunities, including monitoring the Earth's magnetic field for the effects of solar flares and exhaustive surface coverage for strong seismic events.

  17. Dynamic Antenna Alignment Control in Microwave Air-Bridging for Sky-Net Mobile Communication Using Unmanned Flying Platform

    Directory of Open Access Journals (Sweden)

    Chin E. Lin

    2015-01-01

    Full Text Available This paper presents a preliminary study on establishing a mobile point-to-point (P2P microwave air-bridging (MAB between Unmanned Low Altitude Flying Platform (ULAFP and backhaul telecommunication network. The proposed Sky-Net system relays telecom signal for general mobile cellphone users via ULAFP when natural disaster sweeps off Base Transceiver Stations (BTSs. Unlike the conventional fix point microwave bridging application, the ULAFP is cruising on a predefined mission flight path to cover a wider range of service. The difficulty and challenge fall on how to maintain antenna alignment accurately in order to provide the signal strength for MAB. A dual-axis rotation mechanism with embedded controller is designed and implemented on airborne and ground units for stabilizing airborne antenna and tracking the moving ULAFP. The MAB link is established in flight tests using the proposed antenna stabilizing/tracking mechanism with correlated control method. The result supports backbone technique of the Sky-Net mobile communication and verifies the feasibility of airborne e-Cell BTS.

  18. Dark Sky Collaborators: Arizona (AZ) Observatories, Communities, and Businesses

    Science.gov (United States)

    Del Castillo, Elizabeth Alvarez; Corbally, Christopher; Falco, Emilio E.; Green, Richard F.; Hall, Jeffrey C.; Williams, G. Grant

    2015-03-01

    With outdoor lighting ordinances in Arizona first in place around observatories in 1958 and 1972, then throughout the state since 1986, Arizonans have extensive experience working with communities and businesses to preserve our dark skies. Though communities are committed to the astronomy sector in our state, astronomers must collaborate with other stakeholders to implement solutions. Ongoing education and public outreach is necessary to enable ordinance updates as technology changes. Despite significant population increases, sky brightness measurements over the last 20 years show that ordinance updates are worth our efforts as we seek to maintain high quality skies around our observatories. Collaborations are being forged and actions taken to promote astronomy for the longer term in Arizona.

  19. Introduction to the Arizona Sky Island Arthropod Project (ASAP): Systematics, Biogeography, Ecology, and Population Genetics of Arthropods of the Madrean Sky Islands.

    Science.gov (United States)

    Moore, Wendy; Meyer, Wallace M; Eble, Jeffrey A; Franklin, Kimberly; Wiens, John F; Brusca, Richard C

    2013-01-01

    The Arizona Sky Island Arthropod Project (ASAP) is a new multi-disciplinary research program at the University of Arizona that combines systematics, biogeography, ecology, and population genetics to study origins and patterns of arthropod diversity along elevation gradients and among mountain ranges in the Madrean Sky Island Region. Arthropods represent taxonomically and ecologically diverse organisms that drive key ecosystem processes in this mountain archipelago. Using data from museum specimens and specimens we obtain during long-term collecting and monitoring programs, ASAP will document arthropod species across Arizona's Sky Islands to address a number of fundamental questions about arthropods of this region. Baseline data will be used to determine climatic boundaries for target species, which will then be integrated with climatological models to predict future changes in arthropod communities and distributions in the wake of rapid climate change. ASAP also makes use of the natural laboratory provided by the Sky Islands to investigate ecological and genetic factors that influence diversification and patterns of community assembly. Here, we introduce the project, outline overarching goals, and describe preliminary data from the first year of sampling ground-dwelling beetles and ants in the Santa Catalina Mountains.

  20. 77 FR 57602 - Self-Regulatory Organizations; The Options Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2012-09-18

    ... level review of the clearing member's systems and processing capabilities, and review other pertinent... clarify the proper application of such rules to cleared OTC options. MarkitSERV Trade Submission Mechanics... overall level of implied volatilities at three and five years, and to the implied volatility skew. A...

  1. 78 FR 76182 - Self-Regulatory Organizations; The Options Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2013-12-16

    ... that it has a clear and transparent governance structure, as well as clarify the organization, duties... Governance Committee Charter December 11, 2013. Pursuant to Section 19(b)(1) of the Securities Exchange Act... Clearing Corporation (``OCC'') concerns the charter of the Governance Committee (``GC Charter'') of OCC's...

  2. 78 FR 75528 - Federal Government Participation in the Automated Clearing House

    Science.gov (United States)

    2013-12-12

    ... Participation in the Automated Clearing House AGENCY: Bureau of the Fiscal Service, Treasury. ACTION: Notice of... Service (Service) is proposing to amend its regulation governing the use of the Automated Clearing House... Automated Clearing House, Electronic funds transfer, Financial institutions, Fraud, and Incorporation by...

  3. 75 FR 17805 - Self-Regulatory Organizations; the Options Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2010-04-07

    ... currency options traded on national securities exchanges will be treated and cleared as securities options...- settled foreign currency options traded on national securities exchanges will be treated and cleared as...-Settled Foreign Currency Options With One-Cent Exercise Prices April 1, 2010. Pursuant to Section 19(b)(1...

  4. ``Dark Skies are a Universal Resource'' Programs Planned for the International Year of Astronomy

    Science.gov (United States)

    Walker, C. E.; Berglund, K.; Bueter, C.; Crelin, B.; Duriscoe, D.; Moore, C.; Gauthier, A.; Gay, P. L.; Foster, T.; Heatherly, S. A.; Maddalena, R.; Mann, T.; Patten, K.; Pompea, S. M.; Sparks, R.; Schaaf, F.; Simmons, M.; Smith, C.; Smith, M.; Tafreshi, B.

    2008-11-01

    In an effort to help more people appreciate the ongoing loss of a dark night sky for much of the world's population and to raise public knowledge about diverse impacts of excess artificial lighting on local environments, the International Year of Astronomy's Dark Skies Working Group has established six ``Dark Skies'' programs and six ``Dark Skies'' resources. The Dark Skies programs include GLOBE at Night (with Earth Hour), Astronomy Nights in the [National] Parks, Dark Skies Discovery Sites, Quiet Skies, Good Neighbor Lighting, and a digital photography contest. Resources include the light education toolkit, the ``Let There Be Night'' DVD and planetarium program, the 6-minute video, online interactions like Second Life, podcasts, and traveling exhibits. The programs and resources are summarized here, as they were in a poster for the June 2008 ASP/AAS conference. For more information on these programs and resources, visit http://astronomy2009.us/darkskies/.

  5. Combined interpretation of SkyTEM and high-resolution seismic data

    DEFF Research Database (Denmark)

    Høyer, Anne-Sophie; Lykke-Andersen, Holger; Jørgensen, Flemming Voldum

    2011-01-01

    made based on AEM (SkyTEM) and high-resolution seismic data from an area covering 10 km2 in the western part of Denmark. As support for the interpretations, an exploration well was drilled to provide lithological and logging information in the form of resistivity and vertical seismic profiling. Based...... on the resistivity log, synthetic SkyTEM responses were calculated with a varying number of gate-times in order to illustrate the effect of the noise-level. At the exploration well geophysical data were compared to the lithological log; in general there is good agreement. The same tendency was recognised when Sky...

  6. Night sky a field guide to the constellations

    CERN Document Server

    Poppele, Jonathan

    2009-01-01

    Stargazing is among the most peaceful and inspiring outdoor activities. Night Sky, the award-winning book by Jonathan Poppele, makes it more fun than ever! Take a simple approach to finding 62 constellations by focusing on one constellation at a time, instead of attempting to study dizzying charts. Start with the easy-to-find constellations during each season and work toward the more difficult ones. Better yet, you'll learn how to locate any constellation in relation to the Big Dipper, the North Star and the top of the sky. With two ways to locate each constellation, you'll know where in the sky to look and what to look for! Along the way, you'll be introduced to mythology, facts and tidbits, as well as details about the planets, solar system and more! As an added bonus, the book comes with a red-light flashlight for night reading.

  7. Providing Diurnal Sky Cover Data at ARM Sites

    Energy Technology Data Exchange (ETDEWEB)

    Klebe, Dimitri I. [Solmirus Corporation, Colorado Springs, CO (United States)

    2015-03-06

    The Solmirus Corporation was awarded two-year funding to perform a comprehensive data analysis of observations made during Solmirus’ 2009 field campaign (conducted from May 21 to July 27, 2009 at the ARM SGP site) using their All Sky Infrared Visible Analyzer (ASIVA) instrument. The objective was to develop a suite of cloud property data products for the ASIVA instrument that could be implemented in real time and tailored for cloud modelers. This final report describes Solmirus’ research and findings enabled by this grant. The primary objective of this award was to develop a diurnal sky cover (SC) data product utilizing the ASIVA’s infrared (IR) radiometrically-calibrated data and is described in detail. Other data products discussed in this report include the sky cover derived from ASIVA’s visible channel and precipitable water vapor, cloud temperature (both brightness and color), and cloud height inferred from ASIVA’s IR channels.

  8. 77 FR 20445 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2012-04-04

    ... Expand the One-Pot Cross- Margining Program With New York Portfolio Clearing, LLC to Certain ``Market...- Margining Accounts and a Set of Market Professional Cross-Margining Accounts would be required to enter into... nature is unnecessary, given that FICC and NYPC will not permit Clearing Members to enter into Market...

  9. Distribution to the Astronomy Community of the Compressed Digitized Sky Survey

    Science.gov (United States)

    Postman, Marc

    1996-03-01

    The Space Telescope Science Institute has compressed an all-sky collection of ground-based images and has printed the data on a two volume, 102 CD-ROM disc set. The first part of the survey (containing images of the southern sky) was published in May 1994. The second volume (containing images of the northern sky) was published in January 1995. Software which manages the image retrieval is included with each volume. The Astronomical Society of the Pacific (ASP) is handling the distribution of the lOx compressed data and has sold 310 sets as of October 1996. ASP is also handling the distribution of the recently published 100x version of the northern sky survey which is publicly available at a low cost. The target markets for the 100x compressed data set are the amateur astronomy community, educational institutions, and the general public. During the next year, we plan to publish the first version of a photometric calibration database which will allow users of the compressed sky survey to determine the brightness of stars in the images.

  10. BlueSky Cloud Framework: An E-Learning Framework Embracing Cloud Computing

    Science.gov (United States)

    Dong, Bo; Zheng, Qinghua; Qiao, Mu; Shu, Jian; Yang, Jie

    Currently, E-Learning has grown into a widely accepted way of learning. With the huge growth of users, services, education contents and resources, E-Learning systems are facing challenges of optimizing resource allocations, dealing with dynamic concurrency demands, handling rapid storage growth requirements and cost controlling. In this paper, an E-Learning framework based on cloud computing is presented, namely BlueSky cloud framework. Particularly, the architecture and core components of BlueSky cloud framework are introduced. In BlueSky cloud framework, physical machines are virtualized, and allocated on demand for E-Learning systems. Moreover, BlueSky cloud framework combines with traditional middleware functions (such as load balancing and data caching) to serve for E-Learning systems as a general architecture. It delivers reliable, scalable and cost-efficient services to E-Learning systems, and E-Learning organizations can establish systems through these services in a simple way. BlueSky cloud framework solves the challenges faced by E-Learning, and improves the performance, availability and scalability of E-Learning systems.

  11. 77 FR 21277 - Customer Clearing Documentation, Timing of Acceptance for Clearing, and Clearing Member Risk...

    Science.gov (United States)

    2012-04-09

    ..., 23, 37, et al. Customer Clearing Documentation, Timing of Acceptance for Clearing, and Clearing..., 38, and 39 RIN 3038-0092, -0094 Customer Clearing Documentation, Timing of Acceptance for Clearing... implement new statutory provisions enacted by Title VII of the Dodd-Frank Wall Street Reform and Consumer...

  12. All-sky brightness monitoring of light pollution with astronomical methods.

    Science.gov (United States)

    Rabaza, O; Galadí-Enríquez, D; Estrella, A Espín; Dols, F Aznar

    2010-06-01

    This paper describes a mobile prototype and a protocol to measure light pollution based on astronomical methods. The prototype takes three all-sky images using BVR filters of the Johnson-Cousins astronomical photometric system. The stars are then identified in the images of the Hipparcos and General Catalogue of Photometric Data II astronomical catalogues, and are used as calibration sources. This method permits the measurement of night-sky brightness and facilitates an estimate of which fraction is due to the light up-scattered in the atmosphere by a wide variety of man-made sources. This is achieved by our software, which compares the sky background flux to that of many stars of known brightness. The reduced weight and dimensions of the prototype allow the user to make measurements from virtually any location. This prototype is capable of measuring the sky distribution of light pollution, and also provides an accurate estimate of the background flux at each photometric band. (c) 2010 Elsevier Ltd. All rights reserved.

  13. Photometric Analysis of the Pi of the Sky Data

    Directory of Open Access Journals (Sweden)

    M. Siudek

    2011-01-01

    Full Text Available A database containing star measurements from the period 2006–2009 taken by the Pi of the Sky detector located in Las Campanas Observatory in Chile contains more than 2 billion measurements of almost 17 million objects. All measurements are available on the Pi of the Sky web site through a dedicated interface, which also allows users to download selected data. Accurate analysis of Pi of the Sky data is a real challenge, because of a number of factors that can influence the measurements. Possible sources of errors in our measurements include: reading the chip with the shutter open, strong and varying sky background, passing planets or planetoids, and clouds and hot pixels. In order tofacilitate the analysis of variable stars we have developed a system of dedicated filters to remove bad measurements or frames. The spectral sensitivity of the detector is taken into account by appropriate corrections based on the spectral type of reference stars. This process is illustrated by an analysis of the BG Ind system, where we have been able to reduce the systematic uncertainty to about 0.05 magnitudo.

  14. Sky brightness and twilight measurements at Jogyakarta city, Indonesia

    International Nuclear Information System (INIS)

    Herdiwijaya, Dhani

    2016-01-01

    The sky brightness measurements were performed using a portable photometer. A pocket-sized and low-cost photometer has 20 degree area measurement, and spectral ranges between 320-720 nm with output directly in magnitudes per arc second square (mass) unit. The sky brightness with 3 seconds temporal resolutions was recorded at Jogyakarta city (110° 25’ E; 70° 52’ S; elevation 100 m) within 136 days in years from 2014 to 2016. The darkest night could reach 22.61 mpass only in several seconds, with mean value 18.8±0.7 mpass and temperature variation 23.1±1.2 C. The difference of mean sky brightness between before and after midnight was about -0.76 mpass or 2.0 times brighter. Moreover, the sky brightness and temperature fluctuations were more stable in after midnight than in before midnight. It is suggested that city light pollution affects those variations, and subsequently duration of twilight. By comparing twilight brightness for several places, we also suggest a 17° solar dip or about 66 minutes before sunrise for new time of Fajr prayer. (paper)

  15. Multiband photometry and spectroscopy of an all-sky sample of bright white dwarfs

    Science.gov (United States)

    Raddi, R.; Gentile Fusillo, N. P.; Pala, A. F.; Hermes, J. J.; Gänsicke, B. T.; Chote, P.; Hollands, M. A.; Henden, A.; Catalán, S.; Geier, S.; Koester, D.; Munari, U.; Napiwotzki, R.; Tremblay, P.-E.

    2017-12-01

    The upcoming NASA Transiting Exoplanet Survey Satellite (TESS) will obtain space-based uninterrupted light curves for a large sample of bright white dwarfs distributed across the entire sky, providing a very rich resource for asteroseismological studies and the search for transits from planetary debris. We have compiled an all-sky catalogue of ultraviolet, optical and infrared photometry as well as proper motions, which we propose as an essential tool for the preliminary identification and characterization of potential targets. We present data for 1864 known white dwarfs and 305 high-probability white dwarf candidates brighter than 17 mag. We describe the spectroscopic follow-up of 135 stars, of which 82 are white dwarfs and 25 are hot subdwarfs. The new confirmed stars include six pulsating white dwarf candidates (ZZ Cetis), and nine white dwarf binaries with a cool main-sequence companion. We identify one star with a spectroscopic distance of only 25 pc from the Sun. Around the time TESS is launched, we foresee that all white dwarfs in this sample will have trigonometric parallaxes measured by the ESA Gaia mission next year.

  16. Planning and scheduling algorithms for the COSMO-SkyMed constellation

    NARCIS (Netherlands)

    Bianchessi, Nicola; Righini, Giovanni

    2008-01-01

    The COSMO-SkyMed satellite constellation for the observation of the Earth is made of four satellites equipped with radar instruments and is intended for dual use, i.e. for security as well as for environmental monitoring purpose. The planning and scheduling problem for the COSMO-SkyMed constellation

  17. A Mathematical Model of Hourly Solar Radiation in Varying Weather Conditions for a Dynamic Simulation of the Solar Organic Rankine Cycle

    Directory of Open Access Journals (Sweden)

    Taehong Sung

    2015-07-01

    Full Text Available A mathematical model of hourly solar radiation with weather variability is proposed based on the simple sky model. The model uses a superposition of trigonometric functions with short and long periods. We investigate the effects of the model variables on the clearness (kD and the probability of persistence (POPD indices and also evaluate the proposed model for all of the kD-POPD weather classes. A simple solar organic Rankine cycle (SORC system with thermal storage is simulated using the actual weather conditions, and then, the results are compared with the simulation results using the proposed model and the simple sky model. The simulation results show that the proposed model provides more accurate system operation characteristics than the simple sky model.

  18. Building on the International Year of Astronomy: The Dark Skies Awareness Program

    Science.gov (United States)

    Walker, C. E.; Sparks, R. T.; Pompea, S. M.

    2010-08-01

    The International Year of Astronomy (IYA2009) offered opportunities to create exemplary educational programs in astronomy, such as those through the cornerstone project, Dark Skies Awareness (DSA). The preservation of dark skies is important for many reasons including astronomy, energy conservation, wildlife conservation, and even human health. Light pollution is a growing concern, yet it is one of the easiest global environmental problems citizen scientists can address on a local level. The Dark Skies workshop imparted the skills necessary for participants to lead activities at their home institution for conserving dark skies. Workshop participants experienced the hands-on activities, which are suitable for use in a variety of settings including museums, science centers, planetariums, schools, university outreach efforts, and astronomy club events. Participants were immersed in activities that illustrate proper lighting, light pollution's effects on wildlife, and how to measure the darkness of your skies. Several citizen science projects were highlighted, including GLOBE at Night, the Great World Wide Star Count, and How Many Stars. These programs enlist the help of students and the general public to collect data on the night sky conditions in their community and contribute to a worldwide database on light pollution. The data can be analyzed using various online tools. A CD of activities, a light shielding demonstration, a book, a two DVD set with a planetarium show, and many other resources are included in a Dark Skies Education Kit, which workshop participants received at the close of the workshop.

  19. A Regional, Multi-Stakeholder Collaboration for Dark-Sky Protection in Flagstaff, Arizona

    Science.gov (United States)

    Hall, Jeffrey C.

    2018-01-01

    Flagstaff, Arizona is home to almost $200M in astronomical assets, including Lowell Observatory's 4.3-meter Discovery Channel Telescope and the Navy Precision Optical Interferometer, a partnership of Lowell, the U. S. Naval Observatory, and the Naval Research Laboratory. The City of Flagstaff and surrounding Coconino County have comprehensive and effective dark-sky ordinances, but continued regional growth has the potential to degrade the area's dark skies to a level at which observatory missions could be compromised. As a result, a wide array of stakeholders (the observatories, the City, the County, local dark-sky advocates, the business and tourism communities, the national parks and monuments, the Navajo Nation, the U. S. Navy, and others) have engaged in three complementary efforts to ensure that Flagstaff and Coconino County protect the area's dark skies while meeting the needs of the various communities and providing for continued growth and development. In this poster, I will present the status of Flagstaff's conversion to LED outdoor lighting, the Mission Compatibility Study carried out by the Navy to evaluate the dark-sky effects of buildout in Flagstaff, and the Joint Land Use Study (JLUS) presently underway among all the aforementioned stakeholders. Taken in sum, the efforts represent a comprehensive and constructive approach to dark-sky preservation region-wide, and they show what can be achieved when a culture of dark-sky protection is present and deliberate efforts are undertaken to maintain it for decades to come.

  20. The interactive sky: a browsable allsky image

    Science.gov (United States)

    Tancredi, Gonzalo; Da Rosa, Fernando; Roland, Santiago; Almenares, Luciano; Gomez, Fernando

    2015-08-01

    We are conducting a project to make available panoramas of the night sky of the southern hemisphere, based on a mosaic of hundred of photographs. Each allsky panorama is a giant image composed by hundreds of high-resolution photos taken in the course of one night. The panoramas are accessible with a web-browser and the public is able to zoom on them and to see the sky with better quality than the naked eye. We are preparing 4 sets of panoramas corresponding to the four seasons.The individual images are taken with a 16 Mpixels DLSR camera with a 50 mm lens mounted on a Gigapan EPIC robotic camera mounts. These devices and a autoguiding telescope are mounted in a equatorial telescope mount, which allows us to have exposure of several tens seconds. The images are then processed and stitched to create the gigantic panorama, with typical weight of several GBytes.The limiting magnitude is V~8. The panoramas include more than 50 times more stars those detected with the naked eye.In addition to the allsky panoramas, we embedded higher resolution images of specific regions of interest such as: emission nebulae and dark, open and globular clusters and galaxies; which can be zoomed.The photographs have been acquiring since December 2014 in a dark place with low light pollution in the countryside of Uruguay; which allows us to achieve deep sky objects.These panoramas will be available on a website and can be accessed with any browser.This tool will be available for teaching purposes, astronomy popularization or introductory research. Teacher guides will be developed for educational activities at different educational levels.While there are similar projects like Google Sky, the methodology used to generate the giant panoramas allows a much more realistic view, with a background of continuous sky without sharp edges. Furthermore, while the planetarium software is based on drawings of the stars, our panoramas are based on real images.This is the first project with these

  1. Region of Nova Cygni 1975 on the Palomar Sky Survey

    International Nuclear Information System (INIS)

    Beardsley, W.R.; King, M.W.; Russell, J.L.; Stein, J.W.

    1975-01-01

    Careful superposition of a blue Palomar Sky Survey print onto a sectored photograph of Nova Cygni 1975 obtained with the Thaw 30-inch (76-cm) refractor at the Allegheny Observatory decisively confirms the fact that no star brighter than magnitude 21 appears on the Sky Survey print at that position

  2. Radiative sky cooling: fundamental physics, materials, structures, and applications

    Science.gov (United States)

    Sun, Xingshu; Sun, Yubo; Zhou, Zhiguang; Alam, Muhammad Ashraful; Bermel, Peter

    2017-07-01

    Radiative sky cooling reduces the temperature of a system by promoting heat exchange with the sky; its key advantage is that no input energy is required. We will review the origins of radiative sky cooling from ancient times to the modern day, and illustrate how the fundamental physics of radiative cooling calls for a combination of properties that may not occur in bulk materials. A detailed comparison with recent modeling and experiments on nanophotonic structures will then illustrate the advantages of this recently emerging approach. Potential applications of these radiative cooling materials to a variety of temperature-sensitive optoelectronic devices, such as photovoltaics, thermophotovoltaics, rectennas, and infrared detectors, will then be discussed. This review will conclude by forecasting the prospects for the field as a whole in both terrestrial and space-based systems.

  3. Estimating the sky map in gamma-ray astronomy with a Compton telescope

    International Nuclear Information System (INIS)

    Herbert, T.J.

    1991-01-01

    Compton telescopes represent an effective design for γ-ray astronomy in the 1-30 MeV range. However, the complexity of the system response to incident γ-rays has restricted the formulation of optimal methods for processing the data. Since data is only acquired at considerable expense and difficulty a significant investment in both algorithm development and computer processing time are warranted. Current methods for processing low level data form the sky map as either the sum or product of the probabilities that each recorded γ-ray originated from within an area of the sky map. Instead, we model the unknown sky map itself as the means of a Poisson process generating the γ-ray recorded by the telescope. In this paper the authors formulate the probability density function of the data conditioned upon the sky map and derive an iterative algorithm for estimating the sky map by the method of maximum likelihood

  4. SURVEYING THE DYNAMIC RADIO SKY WITH THE LONG WAVELENGTH DEMONSTRATOR ARRAY

    International Nuclear Information System (INIS)

    Lazio, T. Joseph W.; Clarke, Tracy E.; Lane, W. M.; Gross, C.; Kassim, N. E.; Hicks, B.; Polisensky, E.; Stewart, K.; Ray, P. S.; Wood, D.; York, J. A.; Kerkhoff, A.; Dalal, N. Paravastu; Cohen, A. S.; Erickson, W. C.

    2010-01-01

    This paper presents a search for radio transients at a frequency of 73.8 MHz (4 m wavelength) using the all-sky imaging capabilities of the Long Wavelength Demonstrator Array (LWDA). The LWDA was a 16-dipole phased array telescope, located on the site of the Very Large Array in New Mexico. The field of view of the individual dipoles was essentially the entire sky, and the number of dipoles was sufficiently small that a simple software correlator could be used to make all-sky images. From 2006 October to 2007 February, we conducted an all-sky transient search program, acquiring a total of 106 hr of data; the time sampling varied, being 5 minutes at the start of the program and improving to 2 minutes by the end of the program. We were able to detect solar flares, and in a special-purpose mode, radio reflections from ionized meteor trails during the 2006 Leonid meteor shower. We detected no transients originating outside of the solar system above a flux density limit of 500 Jy, equivalent to a limit of no more than about 10 -2 events yr -1 deg -2 , having a pulse energy density ∼>1.5 x 10 -20 J m -2 Hz -1 at 73.8 MHz for pulse widths of about 300 s. This event rate is comparable to that determined from previous all-sky transient searches, but at a lower frequency than most previous all-sky searches. We believe that the LWDA illustrates how an all-sky imaging mode could be a useful operational model for low-frequency instruments such as the Low Frequency Array, the Long Wavelength Array station, the low-frequency component of the Square Kilometre Array, and potentially the Lunar Radio Array.

  5. CFHT's SkyProbe: True Atmospheric Attenuation Measurement in the Telescope Field

    Science.gov (United States)

    Cuillandre, J.-C.; Magnier, E. A.; Isani, S.; Sabin, D.; Knight, W.; Kras, S.; Lai, K.

    Developed at the Canada France Hawaii Telescope (CFHT), SkyProbe is a system that allows the direct measurement of the true attenuation by clouds. This measurement is performed approximately once per min, directly on the field viewed by the telescope. It has been possible to make this system relatively inexpensively due to low cost CCD cameras available on the amateur market. A crucial addition to this hardware is the recent availability of a full-sky photometry catalog at the appropriate depth: the Tycho catalog from the Hipparcos mission. A very important element in the SkyProbe data set creation is the automatic data analysis pipeline, Elixir, developed at CFHT for the improved operation of the CFHT wide-field imagers CFH12K and MegaCam. SkyProbe's FITS images are processed in real time, and the pipeline output (a zero point attenuation) provides the current sky transmission to the observers and aids immediate decision making. These measurements are also attached to the archived data, adding a key tool for future use by other astronomers. Specific features of the detector, such as intra pixel quantum efficiency variations, must be taken into consideration since the data are strongly undersampled.

  6. Verification of the ISO calibration method for field pyranometers under tropical sky conditions

    Science.gov (United States)

    Janjai, Serm; Tohsing, Korntip; Pattarapanitchai, Somjet; Detkhon, Pasakorn

    2017-02-01

    Field pyranomters need to be annually calibrated and the International Organization for Standardization (ISO) has defined a standard method (ISO 9847) for calibrating these pyranometers. According to this standard method for outdoor calibration, the field pyranometers have to be compared to a reference pyranometer for the period of 2 to 14 days, depending on sky conditions. In this work, the ISO 9847 standard method was verified under tropical sky conditions. To verify the standard method, calibration of field pyranometers was conducted at a tropical site located in Nakhon Pathom (13.82o N, 100.04o E), Thailand under various sky conditions. The conditions of the sky were monitored by using a sky camera. The calibration results for different time periods used for the calibration under various sky conditions were analyzed. It was found that the calibration periods given by this standard method could be reduced without significant change in the final calibration result. In addition, recommendation and discussion on the use of this standard method in the tropics were also presented.

  7. Fireballs in the Sky: An Augmented Reality Citizen Science Program

    Science.gov (United States)

    Day, Brian

    2017-01-01

    Fireballs in the Sky is an innovative Australian citizen science program that connects the public with the research of the Desert Fireball Network (DFN). This research aims to understand the early workings of the solar system, and Fireballs in the Sky invites people around the world to learn about this science, contributing fireball sightings via a user-friendly augmented reality mobile app. Tens of thousands of people have downloaded the app world-wide and participated in the science of meteoritics. The Fireballs in the Sky app allows users to get involved with the Desert Fireball Network research, supplementing DFN observations and providing enhanced coverage by reporting their own meteor sightings to DFN scientists. Fireballs in the Sky reports are used to track the trajectories of meteors - from their orbit in space to where they might have landed on Earth. Led by Phil Bland at Curtin University in Australia, the Desert Fireball Network (DFN) uses automated observatories across Australia to triangulate trajectories of meteorites entering the atmosphere, determine pre-entry orbits, and pinpoint their fall positions. Each observatory is an autonomous intelligent imaging system, taking 1000 by 36 megapixel all-sky images throughout the night, using neural network algorithms to recognize events. They are capable of operating for 12 months in a harsh environment, and store all imagery collected. We developed a completely automated software pipeline for data reduction, and built a supercomputer database for storage, allowing us to process our entire archive. The DFN currently stands at 50 stations distributed across the Australian continent, covering an area of 2.5 million square kilometers. Working with DFN's partners at NASA's Solar System Exploration Research Virtual Institute, the team is expanding the network beyond Australia to locations around the world. Fireballs in the Sky allows a growing public base to learn about and participate in this exciting research.

  8. Fireballs in the Sky: an Augmented Reality Citizen Science Program

    Science.gov (United States)

    Day, B. H.; Bland, P.; Sayers, R.

    2017-12-01

    Fireballs in the Sky is an innovative Australian citizen science program that connects the public with the research of the Desert Fireball Network (DFN). This research aims to understand the early workings of the solar system, and Fireballs in the Sky invites people around the world to learn about this science, contributing fireball sightings via a user-friendly augmented reality mobile app. Tens of thousands of people have downloaded the app world-wide and participated in the science of meteoritics. The Fireballs in the Sky app allows users to get involved with the Desert Fireball Network research, supplementing DFN observations and providing enhanced coverage by reporting their own meteor sightings to DFN scientists. Fireballs in the Sky reports are used to track the trajectories of meteors - from their orbit in space to where they might have landed on Earth. Led by Phil Bland at Curtin University in Australia, the Desert Fireball Network (DFN) uses automated observatories across Australia to triangulate trajectories of meteorites entering the atmosphere, determine pre-entry orbits, and pinpoint their fall positions. Each observatory is an autonomous intelligent imaging system, taking 1000×36Megapixel all-sky images throughout the night, using neural network algorithms to recognize events. They are capable of operating for 12 months in a harsh environment, and store all imagery collected. We developed a completely automated software pipeline for data reduction, and built a supercomputer database for storage, allowing us to process our entire archive. The DFN currently stands at 50 stations distributed across the Australian continent, covering an area of 2.5 million km^2. Working with DFN's partners at NASA's Solar System Exploration Research Virtual Institute, the team is expanding the network beyond Australia to locations around the world. Fireballs in the Sky allows a growing public base to learn about and participate in this exciting research.

  9. A new computational method for reactive power market clearing

    International Nuclear Information System (INIS)

    Zhang, T.; Elkasrawy, A.; Venkatesh, B.

    2009-01-01

    After deregulation of electricity markets, ancillary services such as reactive power supply are priced separately. However, unlike real power supply, procedures for costing and pricing reactive power supply are still evolving and spot markets for reactive power do not exist as of now. Further, traditional formulations proposed for clearing reactive power markets use a non-linear mixed integer programming formulation that are difficult to solve. This paper proposes a new reactive power supply market clearing scheme. Novelty of this formulation lies in the pricing scheme that rewards transformers for tap shifting while participating in this market. The proposed model is a non-linear mixed integer challenge. A significant portion of the manuscript is devoted towards the development of a new successive mixed integer linear programming (MILP) technique to solve this formulation. The successive MILP method is computationally robust and fast. The IEEE 6-bus and 300-bus systems are used to test the proposed method. These tests serve to demonstrate computational speed and rigor of the proposed method. (author)

  10. The "All Sky Camera Network"

    Science.gov (United States)

    Caldwell, Andy

    2005-01-01

    In 2001, the "All Sky Camera Network" came to life as an outreach program to connect the Denver Museum of Nature and Science (DMNS) exhibit "Space Odyssey" with Colorado schools. The network is comprised of cameras placed strategically at schools throughout Colorado to capture fireballs--rare events that produce meteorites.…

  11. Estimation of Downwelling Surface Longwave Radiation under Heavy Dust Aerosol Sky

    Directory of Open Access Journals (Sweden)

    Chunlei Wang

    2017-02-01

    Full Text Available The variation of aerosols, especially dust aerosol, in time and space plays an important role in climate forcing studies. Aerosols can effectively reduce land surface longwave emission and re-emit energy at a colder temperature, which makes it difficult to estimate downwelling surface longwave radiation (DSLR with satellite data. Using the latest atmospheric radiative transfer code (MODTRAN 5.0, we have simulated the outgoing longwave radiation (OLR and DSLR under different land surface types and atmospheric profile conditions. The results show that dust aerosol has an obvious “warming” effect to longwave radiation compared with other aerosols; that aerosol longwave radiative forcing (ALRF increased with the increasing of aerosol optical depth (AOD; and that the atmospheric water vapor content (WVC is critical to the understanding of ALRF. A method is proposed to improve the accuracy of DSLR estimation from satellite data for the skies under heavy dust aerosols. The AOD and atmospheric WVC under cloud-free conditions with a relatively simple satellite-based radiation model yielding the high accurate DSLR under heavy dust aerosol are used explicitly as model input to reduce the effects of dust aerosol on the estimation of DSLR. Validations of the proposed model with satellites data and field measurements show that it can estimate the DSLR accurately under heavy dust aerosol skies. The root mean square errors (RMSEs are 20.4 W/m2 and 24.2 W/m2 for Terra and Aqua satellites, respectively, at the Yingke site, and the biases are 2.7 W/m2 and 9.6 W/m2, respectively. For the Arvaikheer site, the RMSEs are 23.2 W/m2 and 19.8 W/m2 for Terra and Aqua, respectively, and the biases are 7.8 W/m2 and 10.5 W/m2, respectively. The proposed method is especially applicable to acquire relatively high accurate DSLR under heavy dust aerosol using MODIS data with available WVC and AOD data.

  12. Radiative sky cooling: fundamental physics, materials, structures, and applications

    Directory of Open Access Journals (Sweden)

    Sun Xingshu

    2017-07-01

    Full Text Available Radiative sky cooling reduces the temperature of a system by promoting heat exchange with the sky; its key advantage is that no input energy is required. We will review the origins of radiative sky cooling from ancient times to the modern day, and illustrate how the fundamental physics of radiative cooling calls for a combination of properties that may not occur in bulk materials. A detailed comparison with recent modeling and experiments on nanophotonic structures will then illustrate the advantages of this recently emerging approach. Potential applications of these radiative cooling materials to a variety of temperature-sensitive optoelectronic devices, such as photovoltaics, thermophotovoltaics, rectennas, and infrared detectors, will then be discussed. This review will conclude by forecasting the prospects for the field as a whole in both terrestrial and space-based systems.

  13. 77 FR 22019 - Self-Regulatory Organizations; ICE Clear Credit LLC; Notice of Filing of Proposed Rule Change to...

    Science.gov (United States)

    2012-04-12

    ... recommendations to approve from the ICE Clear Credit Risk Committee on March 21, 2012, and the ICE Clear Credit Risk Management Subcommittee on March 7, 2012. However, the ICE Clear Credit Board, Risk Committee and...). The concerns raised by the ICE Clear Credit Board, Risk Committee, and Risk Management Subcommittee...

  14. Making beautiful deep-sky images astrophotography with affordable equipment and software

    CERN Document Server

    Parker, Greg

    2017-01-01

    In this updated version of his classic on deep-sky imaging, astrophotographer Greg Parker describes how the latest technology can help amateur astronomers process their own beautiful images. Whether you are taking your own images from a backyard system or processing data from space telescopes, this book shows you how to enhance the visuals in the "electronic darkroom" for maximum beauty and impact. The wealth of options in the astrophotography realm has exploded in the recent past, and Parker proves an able guide for the interested imager to improve his or her comfort level against this exciting new technological backdrop. From addressing the latest DSLR equipment to updating the usage of Hyperstar imaging telescopes and explaining the utility of parallel imaging arrays, this edition brings the book fully up-to-date, and includes clear tutorials, helpful references, and gorgeous color astrophotography by one of the experts in the field.

  15. Spinning projectile's attitude measurement with LW infrared radiation under sea-sky background

    Science.gov (United States)

    Xu, Miaomiao; Bu, Xiongzhu; Yu, Jing; He, Zilu

    2018-05-01

    With the further development of infrared radiation research in sea-sky background and the requirement of spinning projectile's attitude measurement, the sea-sky infrared radiation field is used to carry out spinning projectile's attitude angle instead of inertial sensors. Firstly, the generation mechanism of sea-sky infrared radiation is analysed. The mathematical model of sea-sky infrared radiation is deduced in LW (long wave) infrared 8 ∼ 14 μm band by calculating the sea surface and sky infrared radiation. Secondly, according to the movement characteristics of spinning projectile, the attitude measurement model of infrared sensors on projectile's three axis is established. And the feasibility of the model is analysed by simulation. Finally, the projectile's attitude calculation algorithm is designed to improve the attitude angle estimation accuracy. The results of semi-physical experiments show that the segmented interactive algorithm estimation error of pitch and roll angle is within ±1.5°. The attitude measurement method is effective and feasible, and provides accurate measurement basis for the guidance of spinning projectile.

  16. The Infrared Sky - Science from 2MASS

    International Nuclear Information System (INIS)

    Skrutskie, Michael

    2002-01-01

    The Two Micron All Sky Survey has imaged 100% of the celestial sphere in the near-infrared J (1.2 μm), H (1.6 μm) and Ks (2.2 μm) photometric bands. Pipeline processing of these data has produced catalogs containing 500 million stars and 1.5 million extended sources which will be released later this year. The catalogs are characterized by great photometric uniformity (1%) and precision (2-3%) around the sky as well as good astrometric accuracy (100 mas). This talk will focus on some of the initial scientific results enabled by this database ranging from brown dwarfs in the solar neighborhood to large scale structure in the early universe.

  17. SOUTH POL: Revealing the Polarized Southern Sky

    Science.gov (United States)

    Magalhaes, Antonio Mario Mario; Ramírez, Edgar; Ribeiro, Nadili; Seriacopi, Daiane; Rubinho, Marcelo; Ferrari, Tiberio; Rodrigues, Claudia; Schoenell, William; Herpich, Fabio; Pereyra, Antonio

    2018-01-01

    SOUTH POL will be a survey of the Southern sky in optical polarized light. It will use a newly built polarimeter for T80-S, an 84 cm robotic telescope installed at Cerro Tololo (CTIO), Chile. It will initially cover the sky South of declination -15 deg with a polarimetric accuracy Solar System.The polarimeter has just been commissioned in mid-November, 2017. The data reduction pipeline has already been built. We will describe the instrument and the data reduction, as well as a few of the science cases. The survey is expected to begin midway through the 1st semester of 2018. Both catalog data and raw images will be made available.

  18. Prediction of monthly average global solar radiation based on statistical distribution of clearness index

    International Nuclear Information System (INIS)

    Ayodele, T.R.; Ogunjuyigbe, A.S.O.

    2015-01-01

    In this paper, probability distribution of clearness index is proposed for the prediction of global solar radiation. First, the clearness index is obtained from the past data of global solar radiation, then, the parameters of the appropriate distribution that best fit the clearness index are determined. The global solar radiation is thereafter predicted from the clearness index using inverse transformation of the cumulative distribution function. To validate the proposed method, eight years global solar radiation data (2000–2007) of Ibadan, Nigeria are used to determine the parameters of appropriate probability distribution for clearness index. The calculated parameters are then used to predict the future monthly average global solar radiation for the following year (2008). The predicted values are compared with the measured values using four statistical tests: the Root Mean Square Error (RMSE), MAE (Mean Absolute Error), MAPE (Mean Absolute Percentage Error) and the coefficient of determination (R"2). The proposed method is also compared to the existing regression models. The results show that logistic distribution provides the best fit for clearness index of Ibadan and the proposed method is effective in predicting the monthly average global solar radiation with overall RMSE of 0.383 MJ/m"2/day, MAE of 0.295 MJ/m"2/day, MAPE of 2% and R"2 of 0.967. - Highlights: • Distribution of clearnes index is proposed for prediction of global solar radiation. • The clearness index is obtained from the past data of global solar radiation. • The parameters of distribution that best fit the clearness index are determined. • Solar radiation is predicted from the clearness index using inverse transformation. • The method is effective in predicting the monthly average global solar radiation.

  19. 40 CFR 1048.140 - What are the provisions for certifying Blue Sky Series engines?

    Science.gov (United States)

    2010-07-01

    ... Blue Sky Series engines? 1048.140 Section 1048.140 Protection of Environment ENVIRONMENTAL PROTECTION... Sky Series engines? This section defines voluntary standards for a recognized level of superior emission control for engines designated as “Blue Sky Series” engines. If you certify an engine family under...

  20. Numerical Simulation for a Three-Dimensional Air Pollution Measurement Model in a Heavy Traffic Area under the Bangkok Sky Train Platform

    Directory of Open Access Journals (Sweden)

    Kewalee Suebyat

    2018-01-01

    Full Text Available Air pollutant levels in Bangkok are generally high in street tunnels. They are particularly elevated in almost closed street tunnels such as an area under the Bangkok sky train platform with high traffic volume where dispersion is limited. There are no air quality measurement stations in the vicinity, while the human population is high. In this research, the numerical simulation is used to measure the air pollutant levels. The three-dimensional air pollution measurement model in a heavy traffic area under the Bangkok sky train platform is proposed. The finite difference techniques are employed to approximate the modelled solutions. The vehicle air pollutant emission due to the high traffic volume is mathematically assumed by the pollutant sources term. The simulation is also considered in averaged and moving pollutant sources due to manner vehicle emission. The proposed approximated air pollutant concentration indicators can be replaced by user required gaseous pollutants indices such as NOx, SO2, CO, and PM2.5.

  1. Integration of polarization and chromatic cues in the insect sky compass.

    Science.gov (United States)

    el Jundi, Basil; Pfeiffer, Keram; Heinze, Stanley; Homberg, Uwe

    2014-06-01

    Animals relying on a celestial compass for spatial orientation may use the position of the sun, the chromatic or intensity gradient of the sky, the polarization pattern of the sky, or a combination of these cues as compass signals. Behavioral experiments in bees and ants, indeed, showed that direct sunlight and sky polarization play a role in sky compass orientation, but the relative importance of these cues are species-specific. Intracellular recordings from polarization-sensitive interneurons in the desert locust and monarch butterfly suggest that inputs from different eye regions, including polarized-light input through the dorsal rim area of the eye and chromatic/intensity gradient input from the main eye, are combined at the level of the medulla to create a robust compass signal. Conflicting input from the polarization and chromatic/intensity channel, resulting from eccentric receptive fields, is eliminated at the level of the anterior optic tubercle and central complex through internal compensation for changing solar elevations, which requires input from a circadian clock. Across several species, the central complex likely serves as an internal sky compass, combining E-vector information with other celestial cues. Descending neurons, likewise, respond both to zenithal polarization and to unpolarized cues in an azimuth-dependent way.

  2. Sky-Radiance Models for Monte Carlo Radiative Transfer Applications

    Science.gov (United States)

    Santos, I.; Dalimonte, D.; Santos, J. P.

    2012-04-01

    Photon-tracing can be initialized through sky-radiance (Lsky) distribution models when executing Monte Carlo simulations for ocean color studies. To be effective, the Lsky model should: 1) properly represent sky-radiance features of interest; 2) require low computing time; and 3) depend on a limited number of input parameters. The present study verifies the satisfiability of these prerequisite by comparing results from different Lsky formulations. Specifically, two Lsky models were considered as reference cases because of their different approach among solutions presented in the literature. The first model, developed by the Harrisson and Coombes (HC), is based on a parametric expression where the sun geometry is the unique input. The HC model is one of the sky-radiance analytical distribution applied in state-of-art simulations for ocean optics. The coefficients of the HC model were set upon broad-band field measurements and the result is a model that requires a few implementation steps. The second model, implemented by Zibordi and Voss (ZV), is based on physical expressions that accounts for the optical thickness of permanent gases, aerosol, ozone and water vapour at specific wavelengths. Inter-comparisons between normalized ^LskyZV and ^LskyHC (i.e., with unitary scalar irradiance) are discussed by means of individual polar maps and percent difference between sky-radiance distributions. Sky-radiance cross-sections are presented as well. Considered cases include different sun zenith values and wavelengths (i.e., λ=413, 490 and 665 nm, corresponding to selected center-bands of the MEdium Resolution Imaging Spectrometer MERIS). Results have shown a significant convergence between ^LskyHC and ^LskyZV at 665 nm. Differences between models increase with the sun zenith and mostly with wavelength. For Instance, relative differences up to 50% between ^ L skyHC and ^ LskyZV can be observed in the antisolar region for λ=665 nm and θ*=45°. The effects of these

  3. The gamma-ray sky as seen with HAWC

    Science.gov (United States)

    Hüntemeyer, Petra

    2015-12-01

    The High-Altitude Water Cherenkov (HAWC) TeV Gamma-Ray Observatory located at a site about two hours drive east of Puebla, Mexico on the Sierra Negra plateau (4100 m a.s.l.) was inaugurated in March 2015. The array of 300 water Cherenkov detectors can observe large portions of the sky simultaneously and, with an energy range of 100 GeV to 100 TeV, is currently one of the most sensitive instruments capable of probing particle acceleration near PeV energies. HAWC has already started science operation in the Summer of 2013 and preliminary sky maps have been produced from 260 days of data taken with a partial array. Multiple > 5 σ (pre-trials) hotspots are visible along the galactic plane and some appear to coincide with known TeV sources from the H.E.S.S. catalog, SNRs and molecular cloud associations, and pulsars wind nebulae (PWNe). The sky maps based on partial HAWC array data are discussed as well as the scientific potential of the completed instrument especially in the context of multi-wavelengths studies.

  4. Variable gamma-ray sky at 1 GeV

    International Nuclear Information System (INIS)

    Pshirkov, M. S.; Rubtsov, G. I.

    2013-01-01

    We search for the long-term variability of the gamma-ray sky in the energy range E > 1 GeV with 168 weeks of the gamma-ray telescope Fermi-LAT data. We perform a full sky blind search for regions with variable flux looking for deviations from uniformity. We bin the sky into 12288 pixels using the HEALPix package and use the Kolmogorov-Smirnov test to compare weekly photon counts in each pixel with the constant flux hypothesis. The weekly exposure of Fermi-LAT for each pixel is calculated with the Fermi-LAT tools. We consider flux variations in a pixel significant if the statistical probability of uniformity is less than 4 × 10 −6 , which corresponds to 0.05 false detections in the whole set. We identified 117 variable sources, 27 of which have not been reported variable before. The sources with previously unidentified variability contain 25 active galactic nuclei (AGN) belonging to the blazar class (11 BL Lacs and 14 FSRQs), one AGN of an uncertain type, and one pulsar PSR J0633+1746 (Geminga).

  5. SkyQuery - A Prototype Distributed Query and Cross-Matching Web Service for the Virtual Observatory

    Science.gov (United States)

    Thakar, A. R.; Budavari, T.; Malik, T.; Szalay, A. S.; Fekete, G.; Nieto-Santisteban, M.; Haridas, V.; Gray, J.

    2002-12-01

    We have developed a prototype distributed query and cross-matching service for the VO community, called SkyQuery, which is implemented with hierarchichal Web Services. SkyQuery enables astronomers to run combined queries on existing distributed heterogeneous astronomy archives. SkyQuery provides a simple, user-friendly interface to run distributed queries over the federation of registered astronomical archives in the VO. The SkyQuery client connects to the portal Web Service, which farms the query out to the individual archives, which are also Web Services called SkyNodes. The cross-matching algorithm is run recursively on each SkyNode. Each archive is a relational DBMS with a HTM index for fast spatial lookups. The results of the distributed query are returned as an XML DataSet that is automatically rendered by the client. SkyQuery also returns the image cutout corresponding to the query result. SkyQuery finds not only matches between the various catalogs, but also dropouts - objects that exist in some of the catalogs but not in others. This is often as important as finding matches. We demonstrate the utility of SkyQuery with a brown-dwarf search between SDSS and 2MASS, and a search for radio-quiet quasars in SDSS, 2MASS and FIRST. The importance of a service like SkyQuery for the worldwide astronomical community cannot be overstated: data on the same objects in various archives is mapped in different wavelength ranges and looks very different due to different errors, instrument sensitivities and other peculiarities of each archive. Our cross-matching algorithm preforms a fuzzy spatial join across multiple catalogs. This type of cross-matching is currently often done by eye, one object at a time. A static cross-identification table for a set of archives would become obsolete by the time it was built - the exponential growth of astronomical data means that a dynamic cross-identification mechanism like SkyQuery is the only viable option. SkyQuery was funded by a

  6. The Other Dark Sky

    Science.gov (United States)

    Pazmino, John

    In previous demonstrations of New York's elimination of luminous graffiti from its skies, I focused attention on large-scale projects in the showcase districts of Manhattan. Although these works earned passionate respect in the dark sky movement, they by the same token were disheartening. New York was in some quarters of the movement regarded more as an unachievable Shangri-La than as a role model to emulate. This presentation focuses on scenes of light abatement efforts in parts of New York which resemble other towns in scale and density. I photographed these scenes along a certain bus route in Brooklyn on my way home from work during October 2001. This route circulates through various "bedroom communities," each similar to a mid-size to large town elsewhere in the United States. The sujbects included individual structures - stores, banks, schools - and streetscapes mimicking downtowns. The latter protrayed a mix of atrocious and excellent lighting practice, being that these streets are in transition by the routine process of replacement and renovation. The fixtures used - box lamps, fluted or Fresnel globes, subdued headsigns, indirect lighting - are casually obtainable by property managers at local outlets for lighting apparatus. They are routinely offered to the property managers by storefront designers, security services, contractors, and the community improvement or betterment councils.

  7. Sky brightness and color measurements during the 21 August 2017 total solar eclipse.

    Science.gov (United States)

    Bruns, Donald G; Bruns, Ronald D

    2018-06-01

    The sky brightness was measured during the partial phases and during totality of the 21 August 2017 total solar eclipse. A tracking CCD camera with color filters and a wide-angle lens allowed measurements across a wide field of view, recording images every 10 s. The partially and totally eclipsed Sun was kept behind an occulting disk attached to the camera, allowing direct brightness measurements from 1.5° to 38° from the Sun. During the partial phases, the sky brightness as a function of time closely followed the integrated intensity of the unobscured fraction of the solar disk. A redder sky was measured close to the Sun just before totality, caused by the redder color of the exposed solar limb. During totality, a bluer sky was measured, dimmer than the normal sky by a factor of 10,000. Suggestions for enhanced measurements at future eclipses are offered.

  8. Integrating paleoecology and genetics of bird populations in two sky island archipelagos.

    Science.gov (United States)

    McCormack, John E; Bowen, Bonnie S; Smith, Thomas B

    2008-06-27

    Genetic tests of paleoecological hypotheses have been rare, partly because recent genetic divergence is difficult to detect and time. According to fossil plant data, continuous woodland in the southwestern USA and northern Mexico became fragmented during the last 10,000 years, as warming caused cool-adapted species to retreat to high elevations. Most genetic studies of resulting 'sky islands' have either failed to detect recent divergence or have found discordant evidence for ancient divergence. We test this paleoecological hypothesis for the region with intraspecific mitochondrial DNA and microsatellite data from sky-island populations of a sedentary bird, the Mexican jay (Aphelocoma ultramarina). We predicted that populations on different sky islands would share common, ancestral alleles that existed during the last glaciation, but that populations on each sky island, owing to their isolation, would contain unique variants of postglacial origin. We also predicted that divergence times estimated from corrected genetic distance and a coalescence model would post-date the last glacial maximum. Our results provide multiple independent lines of support for postglacial divergence, with the predicted pattern of shared and unique mitochondrial DNA haplotypes appearing in two independent sky-island archipelagos, and most estimates of divergence time based on corrected genetic distance post-dating the last glacial maximum. Likewise, an isolation model based on multilocus gene coalescence indicated postglacial divergence of five pairs of sky islands. In contrast to their similar recent histories, the two archipelagos had dissimilar historical patterns in that sky islands in Arizona showed evidence for older divergence, suggesting different responses to the last glaciation. This study is one of the first to provide explicit support from genetic data for a postglacial divergence scenario predicted by one of the best paleoecological records in the world. Our results

  9. 77 FR 61649 - Self-Regulatory Organizations; ICE Clear Credit LLC; Order Approving Proposed Rule Change To...

    Science.gov (United States)

    2012-10-10

    ... clearance of the following twenty additional investment grade Standard North American Corporate Single Name... ``Additional Single Names''). As with the Standard North American Corporate Single Names currently cleared, ICC... Single Names do not require any changes to the body of the ICC Rules. ICC will clear the Additional...

  10. 77 FR 24546 - Self-Regulatory Organizations; ICE Clear Credit LLC; Order Approving Proposed Rule To Provide...

    Science.gov (United States)

    2012-04-24

    ... amount of each member's total guaranty fund requirement. In addition, in the event of immediate liquidity...-related liquidity requirements for client-related positions cleared in a clearing participant's customer... applies haircuts to US Treasuries to mitigate liquidity risk. The haircuts as of April 1, 2012 are: 1.25...

  11. The Sloan Digital Sky Survey: Status and prospects

    Energy Technology Data Exchange (ETDEWEB)

    Loveday, J.; SDSS Collaboration

    1996-05-01

    The Sloan Digital Sky Survey (SDSS) is a project to definitively map {pi} steradians of the local Universe. An array of CCD detectors used in drift-scan mode will digitally image the sky in five passbands to a limiting magnitude of r{prime} {approximately} 23. Selected from the imaging survey, 10{sup 6} galaxies and 10{sup 5} quasars will be observed spectroscopically. I describe the current status of the survey, which is due to begin observations early in 1997, and its prospects for constraining models for dark matter in the Universe. 8 refs., 7 figs.

  12. ROTSE All-Sky Surveys for Variable Stars. I. Test Fields

    International Nuclear Information System (INIS)

    Akerlof, C.; Amrose, S.; Balsano, R.; Bloch, J.; Casperson, D.; Fletcher, S.; Gisler, G.; Hills, J.; Kehoe, R.; Lee, B.

    2000-01-01

    The Robotic Optical Transient Search Experiment I (ROTSE-I) experiment has generated CCD photometry for the entire northern sky in two epochs nightly since 1998 March. These sky patrol data are a powerful resource for studies of astrophysical transients. As a demonstration project, we present first results of a search for periodic variable stars derived from ROTSE-I observations. Variable identification, period determination, and type classification are conducted via automatic algorithms. In a set of nine ROTSE-I sky patrol fields covering roughly 2000 deg2, we identify 1781 periodic variable stars with mean magnitudes between m v = 10.0 and m v = 15.5. About 90% of these objects are newly identified as variable. Examples of many familiar types are presented. All classifications for this study have been manually confirmed. The selection criteria for this analysis have been conservatively defined and are known to be biased against some variable classes. This preliminary study includes only 5.6% of the total ROTSE-I sky coverage, suggesting that the full ROTSE-I variable catalog will include more than 32,000 periodic variable stars. (c) (c) 2000. The American Astronomical Society

  13. A Study of Sasin-Animal Sky Map on Chonmunryucho

    Directory of Open Access Journals (Sweden)

    Hong-Jin Yang

    2003-03-01

    Full Text Available Chon-Mun-Ryu-Cho, written (edited by Lee Sun-Ji during the period of King Se-Jong, is a representative astronomy book of Cho-Sun (A.D. 1392 -1910 Dynasty. We find and study in the first page of the book; the description of 28 oriental constellations as a Sasin (four mythical oriental animals-animal sky map which is not widely known yet. The map consists of four groups of constellations, each of which represents the Sasin: Chang-Ryong (dragon, Baek-Ho (tigers with Ki-Rin [Oriental giraffe], Ju-Jak (Chinese phoenix, Hyun-Mu (a tortoise interwined with a snake. Each group (animals spans 2˜7 of 28 oriental constellations As we know from the illustration of the Chon-Sang-Yol-Cha-Bun-Ya-Ji-Do a representative sky map of Cho-Sun Dynasty, astronomy in Cho-Sun Dynasty is closely related to that in Go-Gu-Ryer (B.C. 37 -A.D. 668 Dynasty. Since these Sasin-animals appear in most mural paintings of Go-Gu-Ryer tombs, visualization of sky with these animal constellations could have been established as early as in Go-Gu-Ryer Dynasty. We also reconstruct this ''A Sasin-animal Korean sky map'' based on the shapes of the Sasin and Ki-Rin from Go-Gu-Ryer paintings and 28 oriental constellations in Chon-Sang-Yol-Cha-Bun-Ya-Ji-Do.

  14. The SPHEREx All-Sky Spectral Survey

    Science.gov (United States)

    Bock, James; SPHEREx Science Team

    2018-01-01

    SPHEREx, a mission in NASA's Medium Explorer (MIDEX) program that was selected for Phase A in August 2017, is an all-sky survey satellite designed to address all three science goals in NASA's astrophysics division, with a single instrument, a wide-field spectral imager. SPHEREx will probe the physics of inflation by measuring non-Gaussianity by studying large-scale structure, surveying a large cosmological volume at low redshifts, complementing high-z surveys optimized to constrain dark energy. The origin of water and biogenic molecules will be investigated in all phases of planetary system formation - from molecular clouds to young stellar systems with protoplanetary disks - by measuring ice absorption spectra. We will chart the origin and history of galaxy formation through a deep survey mapping large-scale spatial power in two deep fields located near the ecliptic poles. Following in the tradition of all-sky missions such as IRAS, COBE and WISE, SPHEREx will be the first all-sky near-infrared spectral survey. SPHEREx will create spectra (0.75 – 4.2 um at R = 41; and 4.2 – 5 um at R = 135) with high sensitivity making background-limited observations using a passively-cooled telescope with a wide field-of-view for large mapping speed. During its two-year mission, SPHEREx will produce four complete all-sky maps that will serve as a rich archive for the astronomy community. With over a billion detected galaxies, hundreds of millions of high-quality stellar and galactic spectra, and over a million ice absorption spectra, the archive will enable diverse scientific investigations including studies of young stellar systems, brown dwarfs, high-redshift quasars, galaxy clusters, the interstellar medium, asteroids and comets. All aspects of the instrument and spacecraft have high heritage. SPHEREx requires no new technologies and carries large technical and resource margins on every aspect of the design. SPHEREx is a partnership between Caltech and JPL, following the

  15. The Sky Clears; Poetry of the American Indians.

    Science.gov (United States)

    Day, A. Grove

    More than 200 authentic poems and lyrics of North American Indians are compiled in this anthology. The poetry was translated from tribal languages into English over the past 100 years by students of Indian language, lore, and life. The poems, taken from about 40 North American tribes, include songs of Eskimos of the Arctic coasts, totem-pole…

  16. Receptive fields of locust brain neurons are matched to polarization patterns of the sky.

    Science.gov (United States)

    Bech, Miklós; Homberg, Uwe; Pfeiffer, Keram

    2014-09-22

    Many animals, including insects, are able to use celestial cues as a reference for spatial orientation and long-distance navigation [1]. In addition to direct sunlight, the chromatic gradient of the sky and its polarization pattern are suited to serve as orientation cues [2-5]. Atmospheric scattering of sunlight causes a regular pattern of E vectors in the sky, which are arranged along concentric circles around the sun [5, 6]. Although certain insects rely predominantly on sky polarization for spatial orientation [7], it has been argued that detection of celestial E vector orientation may not suffice to differentiate between solar and antisolar directions [8, 9]. We show here that polarization-sensitive (POL) neurons in the brain of the desert locust Schistocerca gregaria can overcome this ambiguity. Extracellular recordings from POL units in the central complex and lateral accessory lobes revealed E vector tunings arranged in concentric circles within large receptive fields, matching the sky polarization pattern at certain solar positions. Modeling of neuronal responses under an idealized sky polarization pattern (Rayleigh sky) suggests that these "matched filter" properties allow locusts to unambiguously determine the solar azimuth by relying solely on the sky polarization pattern for compass navigation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Anisotropy in the Microwave Sky at 90 GHz: Results From Python III

    OpenAIRE

    Platt, S. R.; Kovac, J.; Dragovan, M.; Peterson, J. B.; Ruhl, J. E.

    1996-01-01

    The third year of observations with the Python microwave background experiment densely sample a $5.5^o\\times 22^o$ region of sky that includes the fields measured during the first two years of observations with this instrument. The sky is sampled in two multipole bands centered at $l \\approx 92$ and $l \\approx 177$. These two data sets are analyzed to place limits on fluctuations in the microwave sky at 90 GHz. Interpreting the observed fluctuations as anisotropy in the cosmic microwave backg...

  18. Losing Sleep to Watch the Night-Sky: The Relationship between Sleep-Length and Noctcaelador

    Science.gov (United States)

    Kelly, William E.; Rose, Callie

    2005-01-01

    For most of history, humans have been watching the night-sky (Hawkins, 1983). Historically, individuals have watched the night-sky for aesthetic appreciation and to gain insights and knowledge (Brecher & Feirtag, 1979). Despite the long history of night-sky watching among humans and the apparent importance of the behavior to large groups of…

  19. A simple proposal for Rayleigh's scaterring experiment

    Directory of Open Access Journals (Sweden)

    Adriano José Ortiz

    2010-03-01

    Full Text Available This work presents an alternative proposal for Rayleigh's scattering experiment presented and discussed in Krapas and Santos (2002 in this journal. Besides being simple and low-cost, the proposal suggested here is also proposing to demonstrate experimentally other physical phenomena such as polarization of light from the sky, the rainbow and reflection on non-conductive surfaces, as well as determine the direction of these biases. The polarization will be observed with the aid of Polaroid obtained from liquid crystal displays taken from damaged electronic devices and the Polaroid polarization direction will be established by the observation of Brewester's angle in reflection experiment.

  20. 75 FR 74110 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Notice of Filing of a Proposed...

    Science.gov (United States)

    2010-11-30

    ... a ``horizontal'' basis (i.e., not limit their provision of clearing services on a vertical basis to... systems post go-live, to allow time for the possible simultaneous integration with multiple major clearing... that it will be able to complete the integration of additional DCMs and/or DCOs in advance of that two...

  1. Night-sky brightness monitoring in Hong Kong: a city-wide light pollution assessment.

    Science.gov (United States)

    Pun, Chun Shing Jason; So, Chu Wing

    2012-04-01

    Results of the first comprehensive light pollution survey in Hong Kong are presented. The night-sky brightness was measured and monitored around the city using a portable light-sensing device called the Sky Quality Meter over a 15-month period beginning in March 2008. A total of 1,957 data sets were taken at 199 distinct locations, including urban and rural sites covering all 18 Administrative Districts of Hong Kong. The survey shows that the environmental light pollution problem in Hong Kong is severe-the urban night skies (sky brightness at 15.0 mag arcsec(- 2)) are on average ~ 100 times brighter than at the darkest rural sites (20.1 mag arcsec(- 2)), indicating that the high lighting densities in the densely populated residential and commercial areas lead to light pollution. In the worst polluted urban location studied, the night-sky at 13.2 mag arcsec(- 2) can be over 500 times brighter than the darkest sites in Hong Kong. The observed night-sky brightness is found to be affected by human factors such as land utilization and population density of the observation sites, together with meteorological and/or environmental factors. Moreover, earlier night skies (at 9:30 p.m. local time) are generally brighter than later time (at 11:30 p.m.), which can be attributed to some public and commercial lightings being turned off later at night. On the other hand, no concrete relationship between the observed sky brightness and air pollutant concentrations could be established with the limited survey sampling. Results from this survey will serve as an important database for the public to assess whether new rules and regulations are necessary to control the use of outdoor lightings in Hong Kong.

  2. THE GAMMA-RAY AND NEUTRINO SKY: A CONSISTENT PICTURE OF FERMI-LAT, MILAGRO, AND ICECUBE RESULTS

    International Nuclear Information System (INIS)

    Gaggero, Daniele; Urbano, Alfredo; Valli, Mauro; Grasso, Dario; Marinelli, Antonio

    2015-01-01

    We compute the γ-ray and neutrino diffuse emission of the Galaxy on the basis of a recently proposed phenomenological model characterized by radially dependent cosmic-ray (CR) transport properties. We show how this model, designed to reproduce both Fermi-LAT γ-ray data and local CR observables, naturally reproduces the anomalous TeV diffuse emission observed by Milagro in the inner Galactic plane. Above 100 TeV our picture predicts a neutrino flux that is about five (two) times larger than the neutrino flux computed with conventional models in the Galactic Center region (full-sky). Explaining in that way up to ∼25% of the flux measured by IceCube, we reproduce the full-sky IceCube spectrum adding an extra-Galactic component derived from the muonic neutrinos flux in the northern hemisphere. We also present precise predictions for the Galactic plane region where the flux is dominated by the Galactic emission

  3. Dark Skies are a Universal Resource: Programs Planned for the International Year of Astronomy

    Science.gov (United States)

    Walker, Constance E.; US IYA Dark Skies Working Group

    2008-05-01

    The dark night sky is a natural resource that is being lost by much of the world's population. This loss is a growing, serious issue that impacts not only astronomical research, but also human health, ecology, safety, economics and energy conservation. One of the themes of the US Node targeted for the International Year of Astronomy (IYA) is "Dark Skies are a Universal Resource". The goal is to raise public awareness of the impact of artificial lighting on local environments by getting people involved locally in a variety of dark skies-related events. To reach this goal, activities are being developed that: 1) Teach about dark skies using new technology (e.g., an activity-based planetarium show on DVD, podcasting, social networking) 2) Provide thematic events on light pollution at star parties and observatory open houses (Dark Skies Teaching Sites, Astronomy Nights in the (National) Parks, Sidewalk Astronomy Nights) 3) Organize events in the arts (e.g., a photography contest) 4) Involve citizen-scientists in unaided-eye and digital-meter star counting programs (e.g., GLOBE at Night, "How Many Stars?” and the Great World Wide Star Count) and 5) Raise awareness about the link between light pollution and public health, economic issues, ecological consequences, energy conservation, safety and security (e.g., The Great Switch Out, Earth Hour, National Dark Skies Week, traveling exhibits and a 6-minute video tutorial on lighting issues). To deliver these programs, strategic networks have been established with the ASP's Night Sky Network's astronomy clubs, Astronomy from the Ground Up's science and nature centers and the Project and Family ASTRO programs, as well as the International Dark-Sky Association, GLOBE and the Astronomical League, among others. The poster presentation will outline the activities being developed, the plans for funding, implementation, marketing and the connections to the global cornerstone IYA project, "Dark Skies Awareness".

  4. Flying between sky islands: the effect of naturally fragmented habitat on butterfly population structure.

    Science.gov (United States)

    Sekar, Sandhya; Karanth, Praveen

    2013-01-01

    High elevation montane areas are called "sky islands" when they occur as a series of high mountains separated by lowland valleys. Different climatic conditions at high elevations makes sky islands a specialized type of habitat, rendering them naturally fragmented compared to more continuous habitat at lower elevations. Species in sky islands face unsuitable climate in the intervening valleys when moving from one montane area to another. The high elevation shola-grassland mosaic in the Western Ghats of southern India form one such sky island complex. The fragmented patches make this area ideal to study the effect of the spatial orientation of suitable habitat patches on population genetic structure of species found in these areas. Past studies have suggested that sky islands tend to have genetically structured populations, possibly due to reduced gene flow between montane areas. To test this hypothesis, we adopted the comparative approach. Using Amplified Fragment Length Polymorphisms, we compared population genetic structures of two closely related, similar sized butterfly species: Heteropsis oculus, a high elevation shola-grassland specialist restricted to the southern Western Ghats, and Mycalesis patnia, found more continuously distributed in lower elevations. In all analyses, as per expectation the sky island specialist H. oculus exhibited a greater degree of population genetic structure than M. patnia, implying a difference in geneflow. This difference in geneflow in turn appears to be due to the natural fragmentation of the sky island complexes. Detailed analysis of a subset of H. oculus samples from one sky island complex (the Anamalais) showed a surprising genetic break. A possible reason for this break could be unsuitable conditions of higher temperature and lower rainfall in the intervening valley region. Thus, sky island species are not only restricted by lack of habitat continuity between montane areas, but also by the nature of the intervening habitat.

  5. Dark Skies Awareness Programs for the International Year of Astronomy

    Science.gov (United States)

    Walker, Constance E.; US IYA Dark Skies Working Group

    2009-05-01

    The arc of the Milky Way seen from a truly dark location is part of our planet's cultural and natural heritage. More than 1/5 of the world population, 2/3 of the United States population and 1/2 of the European Union population have already lost naked-eye visibility of the Milky Way. This loss, caused by light pollution, is a serious and growing issue that impacts astronomical research, the economy, ecology, energy conservation, human health, public safety and our shared ability to see the night sky. For this reason, "Dark Skies” is a cornerstone project of the International Year of Astronomy. Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people worldwide involved in a variety of programs that: 1) Teach about dark skies using new technology (e.g., an activity-based planetarium show on DVD, podcasting, social networking on Facebook and MySpace, a Second Life presence) 2) Provide thematic events on light pollution at star parties and observatory open houses (Dark Skies Discovery Sites, Nights in the (National) Parks, Sidewalk Astronomy) 3) Organize events in the arts (e.g., a photography contest) 4) Involve citizen-scientists in naked-eye and digital-meter star hunting programs (e.g., GLOBE at Night, "How Many Stars?", the Great World Wide Star Count and the radio frequency interference equivalent: "Quiet Skies") and 5) Raise awareness about the link between light pollution and public health, economic issues, ecological consequences, energy conservation, safety and security, and astronomy (e.g., The Starlight Initiative, World Night in Defense of Starlight, International Dark Sky Week, International Dark-Sky Communities, Earth Hour, The Great Switch Out, a traveling exhibit, downloadable posters and brochures). The poster will provide an update, describe how people can continue to participate, and take a look ahead at the program's sustainability. For more information, visit www.darkskiesawareness.org.

  6. X-ray sky

    International Nuclear Information System (INIS)

    Gruen, M.; Koubsky, P.

    1977-01-01

    The history is described of the discoveries of X-ray sources in the sky. The individual X-ray detectors are described in more detail, i.e., gas counters, scintillation detectors, semiconductor detectors, and the principles of X-ray spectrometry and of radiation collimation aimed at increased resolution are discussed. Currently, over 200 celestial X-ray sources are known. Some were identified as nebulae, in some pulsations were found or the source was identified as a binary star. X-ray bursts of novae were also observed. The X-ray radiation is briefly mentioned of spherical star clusters and of extragalactic X-ray sources. (Oy)

  7. Observing floods from space: Experience gained from COSMO-SkyMed observations

    Science.gov (United States)

    Pierdicca, N.; Pulvirenti, L.; Chini, M.; Guerriero, L.; Candela, L.

    2013-03-01

    The COSMO-SkyMed mission offers a unique opportunity to obtain all weather radar images characterized by short revisit time, thus being useful for flood evolution mapping. The COSMO-SkyMed system has been activated several times in the last few years in occasion of flood events all over the world in order to provide very high resolution X-band SAR images useful for flood detection purposes. This paper discusses the major outcomes of the experience gained, within the framework of the OPERA Pilot Project funded by the Italian Space Agency, from using COSMO-SkyMed data for the purpose of near real time generation of flood maps. A review of the mechanisms which determine the imprints of the inundation on the radar images and of the fundamental simulation tools able to predict these imprints and help image interpretation is provided. The approach developed to process the data and to generate the flood maps is also summarized. Then, the paper illustrates the experience gained with COSMO-SkyMed by describing and discussing a number of significant examples. These examples demonstrate the potential of the COSMO-SkyMed system and the suitability of the approach developed for generating the final products, but they also highlight some critical aspects that require further investigations to improve the reliability of the flood maps.

  8. The SPHEREx All-Sky Spectroscopic Survey

    Science.gov (United States)

    Unwin, Stephen C.; SPHEREx Science Team, SPHEREx Project Team

    2016-06-01

    SPHEREx is a mission to conduct an optical-near-IR survey of the entire sky with a spectrum at every pixel location. It was selected by NASA for a Phase A study in its Small Explorer Program; if selected, development would begin in 2016, and the observatory would start a 2-year prime mission in 2020. An all-sky spectroscopic survey can be used to tackle a wide range of science questions. The SPHEREx science team is focusing on three: (1) Probing the physics of inflation through measuring non-Gaussianity from the study of large-scale structure; (2) Studying the origin of water and biogenic molecules in a wide range of physical and chemical environments via ice absorption spectra; (3) Charting the history of star formation in the universe through intensity mapping of the large-scale spatial power. The instrument is a small wide-field telescope operating in the range of 0.75 - 4.8 µm at a spectral resolution of 41.5 in the optical and 150 at the long-wavelength end. It observes in a sun-sync low-earth orbit, covering the sky like WISE and COBE. SPHEREx is a simple instrument that requires no new technology. The Phase A design has substantial technical and resource margins and can be built with low risk. It is a partnership between Caltech and JPL, with Ball Aerospace and the Korea Astronomy and Space Science Institute as major partners. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  9. X-RAY-EMITTING STARS IDENTIFIED FROM THE ROSAT ALL-SKY SURVEY AND THE SLOAN DIGITAL SKY SURVEY

    International Nuclear Information System (INIS)

    Agueeros, Marcel A.; Newsom, Emily R.; Anderson, Scott F.; Hawley, Suzanne L.; Silvestri, Nicole M.; Szkody, Paula; Covey, Kevin R.; Posselt, Bettina; Margon, Bruce; Voges, Wolfgang

    2009-01-01

    The ROSAT All-Sky Survey (RASS) was the first imaging X-ray survey of the entire sky. Combining the RASS Bright and Faint Source Catalogs yields an average of about three X-ray sources per square degree. However, while X-ray source counterparts are known to range from distant quasars to nearby M dwarfs, the RASS data alone are often insufficient to determine the nature of an X-ray source. As a result, large-scale follow-up programs are required to construct samples of known X-ray emitters. We use optical data produced by the Sloan Digital Sky Survey (SDSS) to identify 709 stellar X-ray emitters cataloged in the RASS and falling within the SDSS Data Release 1 footprint. Most of these are bright stars with coronal X-ray emission unsuitable for SDSS spectroscopy, which is designed for fainter objects (g > 15 [mag]). Instead, we use SDSS photometry, correlations with the Two Micron All Sky Survey and other catalogs, and spectroscopy from the Apache Point Observatory 3.5 m telescope to identify these stellar X-ray counterparts. Our sample of 707 X-ray-emitting F, G, K, and M stars is one of the largest X-ray-selected samples of such stars. We derive distances to these stars using photometric parallax relations appropriate for dwarfs on the main sequence, and use these distances to calculate L X . We also identify a previously unknown cataclysmic variable (CV) as a RASS counterpart. Separately, we use correlations of the RASS and the SDSS spectroscopic catalogs of CVs and white dwarfs (WDs) to study the properties of these rarer X-ray-emitting stars. We examine the relationship between (f X /f g ) and the equivalent width of the Hβ emission line for 46 X-ray-emitting CVs and discuss tentative classifications for a subset based on these quantities. We identify 17 new X-ray-emitting DA (hydrogen) WDs, of which three are newly identified WDs. We report on follow-up observations of three candidate cool X-ray-emitting WDs (one DA and two DB (helium) WDs); we have not

  10. The cut-sky cosmic microwave background is not anomalous

    International Nuclear Information System (INIS)

    Pontzen, Andrew; Peiris, Hiranya V.

    2010-01-01

    The observed angular correlation function of the cosmic microwave background has previously been reported to be anomalous, particularly when measured in regions of the sky uncontaminated by Galactic emission. Recent work by Efstathiou et al. presents a Bayesian comparison of isotropic theories, casting doubt on the significance of the purported anomaly. We extend this analysis to all anisotropic Gaussian theories with vanishing mean ( =0), using the much wider class of models to confirm that the anomaly is not likely to point to new physics. On the other hand if there is any new physics to be gleaned, it results from low-l alignments which will be better quantified by a full-sky statistic. We also consider quadratic maximum likelihood power spectrum estimators that are constructed assuming isotropy. The underlying assumptions are therefore false if the ensemble is anisotropic. Nonetheless we demonstrate that, for theories compatible with the observed sky, these estimators (while no longer optimal) remain statistically superior to pseudo-C l power spectrum estimators.

  11. 2012 Australasian sky guide

    CERN Document Server

    Lomb, Nick

    2011-01-01

    Compact, easy to use and reliable, this popular guide contains everything you need to know about the southern night sky with monthly star maps, diagrams and details of all the year's exciting celestial events. Wherever you are in Australia or New Zealand, easy calculations allow you to determine when the Sun, Moon and planets will rise and set throughout the year. Also included is information on the latest astronomical findings from space probes and telescopes around the world.

  12. Dark Skies Ahead? Activities to Raise Awareness during the International Year of Astronomy

    Science.gov (United States)

    Walker, Constance E.; Isbell, D.; Pompea, S.

    2007-12-01

    "Dark Skies as a Universal Resource” is one of 7 themes targeted for the International Year of Astronomy in 2009. The theme's goal is to raise public awareness of the impact of artificial lighting on local environments and the ongoing loss of a dark night sky as a natural resource for much of the world's population. To reach this goal, activities are being developed which highlight dark skies preservation issues 1) through new technology (e.g., programs at planetaria, blogging, podcasting); 2) at events such as star parties and observatory open houses; 3) in arts, entertainment and storytelling (e.g., art competitions, documentaries, lectures, native American traditions); 4) through unaided-eye and digital-meter star count programs involving citizen-scientists; and 5) by relating them to public health, economic issues, ecological consequences, energy conservation, safety and security. A centerpiece of the Dark Skies theme is the unaided-eye and digital-meter versions of the GLOBE at Night program. The unaided-eye version directs citizen-scientists on how to observe and record the brightness of the night sky by matching its appearance toward the constellation of Orion with one of 7 stellar maps of different limiting magnitudes. For the "digital” version, low-cost meters are used by citizen-scientists to measure the integrated sky brightness. Data sets and maps of both versions are supplied on-line for further capstone activities. In the presentation, we will outline the activities being developed as well as plans for funding, implementation, marketing and the connections to the global cornerstone IYA project, "Dark Skies Awareness".

  13. Thermography hogging the limelight at Big Sky

    Energy Technology Data Exchange (ETDEWEB)

    Plastow, C. [Fluke Electronics Canada, Mississauga, ON (Canada)

    2010-02-15

    The high levels of humidity and ammonia found at hog farms can lead to premature corrosion of electrical systems and create potential hazards, such as electrical fires. Big Sky Farms in Saskatchewan has performed on-site inspections at its 44 farms and 16 feed mills using handheld thermography technology from Fluke Electronics. Ti thermal imaging units save time and simplify inspections. The units could be used for everything, from checking out the bearings at the feed mills to electrical circuits and relays. The Ti25 is affordable and has the right features for a preventative maintenance program. Operators of Big Sky Farms use the Ti25 to inspect all circuit breakers of 600 volts or lower as well as transformers where corrosion often causes connections to break off. The units are used to look at bearings, do scanning and thermal imaging on motors. To date, the Ti25 has detected and highlighted 5 or 6 problems on transformers alone that could have been major issues. At one site, the Ti25 indicated that all 30 circuit breakers had loose connections and were overeating. Big Sky Farms fixed the problem right away before a disaster happened. In addition to reducing inspection times, the Ti25 can record all measurements and keep a record of all the readings for downloading. 2 figs.

  14. Photometric Analysis of Pi of the Sky Data

    Directory of Open Access Journals (Sweden)

    Rafał Opiela

    2013-01-01

    Full Text Available Two fully automatic Pi of the Sky detectors with a large field of view, located in Spain (INTA and in Chile (SPDA observe the sky in search of rare optical phenomena, and also collect observations which include many kinds of variable stars. To be able to draw proper conclusions from the data that is received, adequate quality of the detectors is very important. Pi of the Sky data are subject to systematic errors caused by various factors, e.g. cloud cover seen as significant fluctuations in the number of stars observed by the detector, problems with conducting mounting, a strong background of the moon or the passage of a bright object, e.g. a planet, near the observed star. Some of these adverse effects are already detected during cataloging of the individual measurements, but this is not sufficient to make the quality of the data satisfactory for us. In order to improve the quality of our data, we developed two new procedures based on two different approaches. In this paper we will say some words about these procedures, give some examples, and show how these procedures improve the quality of our data.

  15. The gamma-ray sky as seen with HAWC

    Directory of Open Access Journals (Sweden)

    Hüntemeyer Petra

    2015-01-01

    Full Text Available The High-Altitude Water Cherenkov (HAWC TeV Gamma-Ray Observatory located at a site about two hours drive east of Puebla, Mexico on the Sierra Negra plateau (4100 m a.s.l. was inaugurated in March 2015. The array of 300 water Cherenkov detectors can observe large portions of the sky simultaneously and, with an energy range of 100 GeV to 100 TeV, is currently one of the most sensitive instruments capable of probing particle acceleration near PeV energies. HAWC has already started science operation in the Summer of 2013 and preliminary sky maps have been produced from 260 days of data taken with a partial array. Multiple > 5 σ (pre-trials hotspots are visible along the galactic plane and some appear to coincide with known TeV sources from the H.E.S.S. catalog, SNRs and molecular cloud associations, and pulsars wind nebulae (PWNe. The sky maps based on partial HAWC array data are discussed as well as the scientific potential of the completed instrument especially in the context of multi-wavelengths studies.

  16. ACS/WFC Sky Flats from Frontier Fields Imaging

    Science.gov (United States)

    Mack, J.; Lucas, R. A.; Grogin, N. A.; Bohlin, R. C.; Koekemoer, A. M.

    2018-04-01

    Parallel imaging data from the HST Frontier Fields campaign (Lotz et al. 2017) have been used to compute sky flats for the ACS/WFC detector in order to verify the accuracy of the current set of flat field reference files. By masking sources and then co-adding many deep frames, the F606W and F814W filters have enough combined background signal that from Poisson statistics are efficiency tracks the thickness of the two WFC chips. Observations of blue and red calibration standards measured at various positions on the detector (Bohlin et al. 2017) confirm the fidelity of the F814W flat, with aperture photometry consistent to 1% across the FOV, regardless of spectral type. At bluer wavelengths, the total sky background is substantially lower, and the F435W sky flat shows a combination of both flat errors and detector artifacts. Aperture photometry of the red standard star shows a maximum deviation of 1.4% across the array in this filter. Larger residuals up to 2.5% are found for the blue standard, suggesting that the spatial sensitivity in F435W depends on spectral type.

  17. Study of X-ray transients with Scanning Sky Monitor (SSM) onboard ...

    Indian Academy of Sciences (India)

    M. C. RAMADEVI

    MS received 1 September 2017; accepted 19 December 2017; published online 10 February 2018. Abstract. Scanning Sky Monitor (SSM) onboard AstroSat is an X-ray sky monitor in the ..... 31(2–3), 99. Ramadevi M. C., Seetha S., Babu V. C., Ashoka B. N., Sreeku- mar P. 2006, Optimization of Gas Proportional Coun-.

  18. Protecting Dark Skies as a State-Wide Resource

    Science.gov (United States)

    Allen, Lori E.; Walker, Constance E.; Hall, Jeffrey C.; Larson, Steve; Williams, Grant; Falco, Emilio; Hinz, Joannah; Fortin, Pascal; Brocious, Dan; Corbally, Christopher; Gabor, Paul; Veillet, Christian; Shankland, Paul; Jannuzi, Buell; Cotera, Angela; Luginbuhl, Christian

    2018-01-01

    The state of Arizona contains the highest concentration of research telescopes in the continental United States, contributing more than a quarter of a billion dollars annually to the state's economy. Protecting the dark skies above these observatories is both good for astronomy and good for the state's economy. In this contribution we describe how a coalition of Arizona observatories is working together to protect our dark skies. Efforts date back to the creation of one of the first Outdoor Lighting Codes in the United States and continue today, including educational outreach, public policy engagement, and consensus building. We review some proven strategies, highlight recent successes and look at current threats.

  19. 2MASS - The 2 Micron All Sky Survey

    Science.gov (United States)

    Kleinmann, S. G.

    1992-01-01

    This paper describes a new sky survey to be carried out in three wavebands, J(1.25 m), H(1.65 m), and K(2.2 m). The limiting sensitivity of the survey, 10 sigma detection of point sources with K not greater than 14 mag, coupled with its all-sky coverage, were selected primarily to support studies of the large-scale structure of the Milky Way and the Local Universe. The survey requires construction of a pair of observing facilities, one each for the Northern and Southern Hemispheres. Operations are scheduled to begin in 1995. The data will begin becoming publicly available soon thereafter.

  20. 77 FR 17537 - Self-Regulatory Organizations; ICE Clear Europe Limited; Notice of Filing of Proposed Rule Change...

    Science.gov (United States)

    2012-03-26

    ... determined separately in respect of the Clearing Member's Proprietary Account and any relevant customer... safeguarding of securities and funds, which are in the custody or control of ICE Clear Europe or for which it...

  1. Diamonds in the Sky

    Science.gov (United States)

    Brotherton, M.

    2004-12-01

    My first science fiction novel, Star Dragon, just recently available in paperback from Tor, features a voyage to the cataclysmic variable star system SS Cygni. My second novel, Spider Star, to appear early in 2006, takes place in and around a dark matter ``planet'' orbiting a neutron star. Both novels are ``hard'' science fiction, relying on accurate physics to inform the tales. It's possible to bring to life abstract concepts like special relativity, and alien environments like accretion disks, by using science fiction. Novels are difficult to use in a science class, but short stories offer intriguing possibilities. I'm planning to edit an anthology of hard science fiction stories that contain accurate science and emphasize fundamental ideas in modern astronomy. The working title is Diamonds in the Sky. The collection will be a mix of original stories and reprints, highlighting challenging concepts covered in a typical introductory astronomy course. Larry Niven's classic story, ``Neutron Star," is an excellent demonstration of extreme tidal forces in an astronomical context. Diamonds in the Sky will include forewards and afterwards to the stories, including discussion questions and mathematical formulas/examples as appropriate. I envision this project will be published electronically or through a print-on-demand publisher, providing long-term availabilty and keeping low cost. I encourage interested parties to suggest previously published stories, or to suggest which topics must be included.

  2. Clear Liquor Scrubbing with Anhydrite Production

    International Nuclear Information System (INIS)

    Hargrove, O. W.; Carey, T. R.; Lowell, P. S.; Meserole, F. B.; Rhudy, R. G.; Feeley, Thomas J.

    1997-01-01

    The objective of this project to develop an advanced flue gas desulfurization (FGD) process that has decreased capital and operating costs, higher SO 2 removal efficiency, and better by-product solids quality than existing, commercially available technology. A clear liquor process (which uses a scrubbing liquid with no solids) will be used to accomplish this objective rather than a slurry liquor process (which contains solids). This clear liquor scrubbing (CLS) project is focused on three research areas: (1) Development of a clear liquor scrubbing process that uses a clear solution to remove SO 2 from flue gas and can be operated under inhibited-oxidation conditions; (2) Development of an anhydrite process that converts precipitated calcium sulfite to anhydrous calcium sulfate (anhydrite); and (3) Development of an alkali/humidification process to remove HCl from flue gas upstream of the FGD system. The anhydrite process also can be retrofit into existing FGD systems to produce a valuable by-product as an alternative to gypsum. This fits well into another of FETC's PRDA objectives of developing an advanced byproduct recovery subsystem capable of transforming SO 2 into a useable byproduct or high-volume valuable commodities of interest. This paper describes the proposed processes, outlines the test approach, and preliminary Phase I test results

  3. A new service support tool for COSMO-SkyMed: civil user coordination service and civil request management optimization

    Science.gov (United States)

    Daraio, M. G.; Battagliere, M. L.; Sacco, P.; Fasano, L.; Coletta, A.

    2015-10-01

    COSMO-SkyMed is a dual-use program for both civilian and defense provides user community (institutional and commercial) with SAR data in several environmental applications. In the context of COSMO-SkyMed data and User management, one of the aspects carefully monitored is the user satisfaction level, it is links to satisfaction of submitted user requests. The operational experience of the first years of operational phase, and the consequent lessons learnt by the COSMO-SkyMed data and user management, have demonstrated that a lot of acquisition rejections are due to conflicts (time conflicts or system conflicts) among two or more civilian user requests, and they can be managed and solved implementing an improved coordination of users and their requests on a daily basis. With this aim a new Service Support Tool (SST) has been designed and developed to support the operators in the User Request coordination. The Tool allow to analyze conflicts among Acquisition Requests (ARs) before the National Rankization phase and to elaborate proposals for conflict resolution. In this paper the most common causes of the occurred rejections will be showed, for example as the impossibility to aggregate different orders, and the SST functionalities will be described, in particular how it works to remove or minimize the conflicts among different orders.

  4. Planck 2013 results. XI. All-sky model of thermal dust emission

    DEFF Research Database (Denmark)

    Abergel, A.; Ade, P. A. R.; Aghanim, N.

    2014-01-01

    This paper presents an all-sky model of dust emission from the Planck 353, 545, and 857 GHz, and IRAS 100 mu m data. Using a modified blackbody fit to the data we present all-sky maps of the dust optical depth, temperature, and spectral index over the 353-3000 GHz range. This model is a good repr...

  5. 78 FR 21046 - Amendment to Rule Filing Requirements for Dually-Registered Clearing Agencies

    Science.gov (United States)

    2013-04-09

    ... clearing operations of a Registered Clearing Agency and are not linked to securities clearing operations...: (A) does not adversely affect the safeguarding of securities or funds in the custody or control of...)(ii) to designate proposed rule changes concerning the agency's security futures operations as taking...

  6. 78 FR 62846 - Self-Regulatory Organizations; National Securities Clearing Corporation; Notice of Filing...

    Science.gov (United States)

    2013-10-22

    ... Proposed Rule Change, as Previously Modified by Amendment Nos. 1 and 2, To Institute Supplemental Liquidity Deposits to Its Clearing Fund Designed To Increase Liquidity Resources To Meet Its Liquidity Needs October...'') to provide for supplemental liquidity deposits to its Clearing Fund (the ``NSCC Clearing Fund'') to...

  7. Sacred Sky and Cyberspace

    Science.gov (United States)

    Clynes, F.

    2011-06-01

    The concept of the sacred world beyond the stars found expression in the works of Plato, into Gnosticism and was incorporated into Christianity where medieval images of the cosmos pictured the heavenly domain as beyond the stars. Today cyberspace literature abounds with descriptions of a transmundane space, a great Beyond. This talk looks at current views of cyberspace and asks if they are a re-packaging of the age-old concept of a sacred sky in a secular and technological format?

  8. CLEAR: Prospects for a low threshold neutrino experiment at the Spallation Neutron Source

    International Nuclear Information System (INIS)

    Scholberg, Kate

    2008-01-01

    A low-threshold neutrino scattering experiment at a high intensity stopped-pion neutrino source has the potential to measure coherent neutral current neutrino-nucleus elastic scattering. A promising prospect for the measurement of this process is a proposed noble-liquid-based experiment, dubbed CLEAR (Coherent Low Energy A (Nuclear) Recoils), at the Spallation Neutron Source. This poster will describe the CLEAR proposal and its physics reach.

  9. The use of a sky camera for solar radiation estimation based on digital image processing

    International Nuclear Information System (INIS)

    Alonso-Montesinos, J.; Batlles, F.J.

    2015-01-01

    The necessary search for a more sustainable global future means using renewable energy sources to generate pollutant-free electricity. CSP (Concentrated solar power) and PV (photovoltaic) plants are the systems most in demand for electricity production using solar radiation as the energy source. The main factors affecting final electricity generation in these plants are, among others, atmospheric conditions; therefore, knowing whether there will be any change in the solar radiation hitting the plant's solar field is of fundamental importance to CSP and PV plant operators in adapting the plant's operation mode to these fluctuations. Consequently, the most useful technology must involve the study of atmospheric conditions. This is the case for sky cameras, an emerging technology that allows one to gather sky information with optimal spatial and temporal resolution. Hence, in this work, a solar radiation estimation using sky camera images is presented for all sky conditions, where beam, diffuse and global solar radiation components are estimated in real-time as a novel way to evaluate the solar resource from a terrestrial viewpoint. - Highlights: • Using a sky camera, the solar resource has been estimated for one minute periods. • The sky images have been processed to estimate the solar radiation at pixel level. • The three radiation components have been estimated under all sky conditions. • Results have been presented for cloudless, partially-cloudy and overcast conditions. • For beam and global radiation, the nRMSE value is of about 11% under overcast skies.

  10. The fast transient sky with Gaia

    Science.gov (United States)

    Wevers, Thomas; Jonker, Peter G.; Hodgkin, Simon T.; Kostrzewa-Rutkowska, Zuzanna; Harrison, Diana L.; Rixon, Guy; Nelemans, Gijs; Roelens, Maroussia; Eyer, Laurent; van Leeuwen, Floor; Yoldas, Abdullah

    2018-01-01

    The ESA Gaia satellite scans the whole sky with a temporal sampling ranging from seconds and hours to months. Each time a source passes within the Gaia field of view, it moves over 10 charge coupled devices (CCDs) in 45 s and a light curve with 4.5 s sampling (the crossing time per CCD) is registered. Given that the 4.5 s sampling represents a virtually unexplored parameter space in optical time domain astronomy, this data set potentially provides a unique opportunity to open up the fast transient sky. We present a method to start mining the wealth of information in the per CCD Gaia data. We perform extensive data filtering to eliminate known onboard and data processing artefacts, and present a statistical method to identify sources that show transient brightness variations on ≲2 h time-scales. We illustrate that by using the Gaia photometric CCD measurements, we can detect transient brightness variations down to an amplitude of 0.3 mag on time-scales ranging from 15 s to several hours. We search an area of ∼23.5 deg2 on the sky and find four strong candidate fast transients. Two candidates are tentatively classified as flares on M-dwarf stars, while one is probably a flare on a giant star and one potentially a flare on a solar-type star. These classifications are based on archival data and the time-scales involved. We argue that the method presented here can be added to the existing Gaia Science Alerts infrastructure for the near real-time public dissemination of fast transient events.

  11. Dark Skies Awareness Cornerstone Project for the International Year of Astronomy

    Science.gov (United States)

    Walker, C. E.; Pompea, S. M.; Iya Dark Skies Awareness Working Group

    2010-12-01

    Programs that were part of the International Year of Astronomy 2009 (IYA2009) Dark Skies Awareness (DSA) Cornerstone Project have been successfully implemented around the world to promote social awareness of the effects of light pollution on public health, economic issues, ecological consequences, energy conservation, safety and security, nightscape aesthetics and especially astronomy. In developing the programs, DSA Cornerstone Project found that to influence cultural change effectively — to make people literally look up and see the light — we must make children a main focus, use approaches that offer involvement on many levels, from cursory to committed, and offer involvement via many venues. We must make the programs and resources as turn-key as possible, especially for educators — and provide ways to visualize the problem with simple, easily grasped demonstrations. The programs spanned a wide range; from new media technology for the younger generation, to an event in the arts, to various types of educational materials, to the promotion of dark skies communities, to national and international events and to global citizen science programs. The DSA Cornerstone Project is continuing most all of these programs beyond IYA2009. The International Dark-Sky Association as well as the Starlight Initiative is endorsing and helping to continue with some of the most successful programs from the DSA. The GLOBE at Night campaign is adding a research component that examines light pollution’s affects on wildlife. Dark Skies Rangers activities are being implemented in Europe through the Galileo Teacher Training Program. The new “One Star at a Time” will engage people to protect the night sky through personal pledges and registration of public stargazing areas or StarParks, like the newest one in Italy. The Starlight Initiative’s World Night in Defence of the Starlight will take place on the Vernal Equinox. DSA will again oversee the Dark Skies portion of Global

  12. Students in Advanced Research for Sky Surveillance

    National Research Council Canada - National Science Library

    Gehrels, Tom

    1997-01-01

    .... to 2000 sqare degrees of sky are searched each year to a V magnitude level of 21.3. Spacewatch discoveries support studies of the evolution of the Centaur, Trojan, Main-Belt, and Earth-approaching asteroid populations...

  13. Consideration of sky-shine radiation effects for the development of Korean regulatory guidance about industrial radiography

    International Nuclear Information System (INIS)

    Yong Ki Chi; Bokyun Seo; Wantae Kim

    2015-01-01

    Although most of the sky-shine radiation levels in industrial radiography are below regulatory limits, sky-shine radiation could make a valuable contribution to the total radiation level near shielding facility with little shielding and open field without shielding. Therefore sky-shine radiation should be thoroughly predicted and supervised with the ALARA principle. In this study, we simulated sky-shine radiation for mobile irradiators using MCNP and newly suggested the equation for calculating sky-shine radiation. Also these results were applied to developing Korean regulatory guidance about industrial radiography and to recommending the requirement of the facility design, controlled or supervised area at work places. (author)

  14. Night Sky Brightness Measurement by the Public through a Mobile Phone App

    Science.gov (United States)

    Kamegai, Kazuhisa; Tsukada, Ken; Inoue, Hiroki

    2015-08-01

    The darkness of night sky is important naturally for astronomy researchers, and also for the public people. Particularly, it is meaningful for those who begin to have an interest in gazing stars. Some previous studies suggest that light pollution may affect human health and ecosystem in various ways. Furthermore, it causes a lot of waste of electric energy for lighting.In Japan, the night sky brightness had been measured by Ministry of Environment for a few decades. Recently some global efforts have been also conducted. However the number of measured position is limited because the measurement needs some apparatus and takes long time.Here we show a result of quick and easy measurements of night sky brightness by the public people through a mobile phone app. The measurements were conducted in cooperation between some members of the Tenpla project and a weather forecasting company. The app has been developed by the company and has been installed by over 6.5 million people, which allow us to get a large number of data. Our purposes are (1) making map of night sky brightness all over Japan and (2) providing an opportunity to enjoy gazing star for those who are not usually interested in astronomy.As an interactive function of the app, we put a questionnaire of four choices in which we ask users how many stars are visible in a part of the constellation of Orion. When users answer the question, we get the answer and the position where they are. Depending on the answer, we can roughly recognize the sky brightness of the position.We opened the measurements for several nights. As a result, we could get 4000 - 5000 data all over the country per night. The map of each night is a snapshot of sky brightness of the night including effect of the weather. For example we can recognize that the sky is getting darker as a function of distance from the metropolitan area of Tokyo. We will show the detail results in the presentation.

  15. Sky Glow from Cities: The Army Illumination Model v2

    Science.gov (United States)

    2011-09-01

    corresponding to one 10th magnitude star per square degree and will not be pursued further here). Benn and Ellison find that the sky brightness at La Palma ...not have electricity, liquid and pressurized lamps are 23 included. For these latter two, liquid Citronella, lamp oil , liquid paraffin and...Properties; AFGL-TR-79-0214; Air Force Geophysics Laboratory: Hanscom Air Force Base, MA, 1979. 19. Benn, C. R. and Ellison, S. L. La Palma Night-Sky

  16. 77 FR 7652 - Self-Regulatory Organizations; ICE Clear Europe Limited; Notice of Proposed Rule Change To Revise...

    Science.gov (United States)

    2012-02-13

    ... Procedures Related to Certain Technical and Operational Changes Relating to Credit Default Swap Contracts... changes described below with its Clearing Members. These changes seek to improve drafting and cross... purpose of specifying technical operational changes relating to CDS Contracts (as defined at ICE Clear...

  17. MonetDB/SQL Meets SkyServer: the Challenges of a Scientific Database.

    NARCIS (Netherlands)

    M.G. Ivanova (Milena); N.J. Nes (Niels); R.A. Goncalves (Romulo); M.L. Kersten (Martin)

    2007-01-01

    textabstractThis paper presents our experiences in porting the Sloan Digital Sky Survey(SDSS)/ SkyServer to the state-of-the-art open source database system MonetDB/SQL. SDSS acts as a well-documented benchmark for scientific database management. We have achieved a fully functional prototype for the

  18. LoFASM: A Low Frequency All Sky Monitor for Radio Transients and Student Training

    Science.gov (United States)

    2015-09-02

    SECURITY CLASSIFICATION OF: The Low-Frequency All- Sky Monitor (LoFASM) is an innovative new radio astronomy observatory. Designed and built by...Feb-2015 Approved for Public Release; Distribution Unlimited Final Report: LoFASM: A Low Frequency All Sky Monitor for Radio Transients and Student...reviewed journals: Number of Papers published in non peer-reviewed journals: Final Report: LoFASM: A Low Frequency All Sky Monitor for Radio Transients and

  19. SkyProbe, monitoring the absolute atmospheric transmission in the optical

    Science.gov (United States)

    Cuillandre, Jean-charles; Magnier, Eugene; Mahoney, William

    2011-03-01

    Mauna Kea is known for its pristine seeing conditions, but sky transparency can be an issue for science operations since 25% of the night are not photometric, mostly due to high-altitude cirrus. Since 2001, the original single-channel SkyProbe has gathered one exposure every minute during each observing night using a small CCD camera with a very wide field of view (35 sq. deg.) encompassing the region pointed by the telescope for science operations, and exposures long enough (40 seconds) to capture at least 100 stars of Hipparcos' Tychos catalog at high galactic latitudes (and up to 600 stars at low galactic latitudes). A key advantage of SkyProbe over direct thermal infrared imaging detection of clouds, is that it allows an accurate absolute measurement, within 5%, of the true atmospheric absorption by clouds affecting the data being gathered by the telescope's main science instrument. This system has proven crucial for decision making in the CFHT queued service observing (QSO), representing today 80% of the telescope time: science exposures taken in non-photometric conditions are automatically registered for being re-observed later on (at 1/10th of the original exposure time per pointing in the observed filters) to ensure a proper final absolute photometric calibration. The new dual color system (simultaneous B&V bands) will allow a better characterization of the sky properties atop Mauna Kea and will enable a better detection of the thinner cirrus (absorption down to 0.02 mag., i.e. 2%). SkyProbe is operated within the Elixir pipeline, a collection of tools used for handling the CFHT CCD mosaics (CFH12K and MegaCam), from data pre-processing to astrometric and photometric calibration.

  20. Planck 2013 results. XI. All-sky model of thermal dust emission

    CERN Document Server

    Abergel, A; Aghanim, N; Alina, D; Alves, M I R; Armitage-Caplan, C; Arnaud, M; Ashdown, M; Atrio-Barandela, F; Aumont, J; Baccigalupi, C; Banday, A J; Barreiro, R B; Bartlett, J G; Battaner, E; Benabed, K; Benoît, A; Benoit-Lévy, A; Bernard, J -P; Bersanelli, M; Bielewicz, P; Bobin, J; Bock, J J; Bonaldi, A; Bond, J R; Borrill, J; Bouchet, F R; Boulanger, F; Bridges, M; Bucher, M; Burigana, C; Butler, R C; Cardoso, J -F; Catalano, A; Chamballu, A; Chary, R -R; Chiang, H C; Chiang, L -Y; Christensen, P R; Church, S; Clemens, M; Clements, D L; Colombi, S; Colombo, L P L; Combet, C; Couchot, F; Coulais, A; Crill, B P; Curto, A; Cuttaia, F; Danese, L; Davies, R D; Davis, R J; de Bernardis, P; de Rosa, A; de Zotti, G; Delabrouille, J; Delouis, J -M; Désert, F -X; Dickinson, C; Diego, J M; Dole, H; Donzelli, S; Doré, O; Douspis, M; Dupac, X; Efstathiou, G; Enßlin, T A; Eriksen, H K; Falgarone, E; Finelli, F; Forni, O; Frailis, M; Fraisse, A A; Franceschi, E; Galeotta, S; Ganga, K; Ghosh, T; Giard, M; Giardino, G; Giraud-Héraud, Y; González-Nuevo, J; Górski, K M; Gratton, S; Gregorio, A; Grenier, I A; Gruppuso, A; Guillet, V; Hansen, F K; Hanson, D; Harrison, D; Helou, G; Henrot-Versillé, S; Hernández-Monteagudo, C; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Holmes, W A; Hornstrup, A; Hovest, W; Huffenberger, K M; Jaffe, A H; Jaffe, T R; Jewell, J; Joncas, G; Jones, W C; Juvela, M; Keihänen, E; Keskitalo, R; Kisner, T S; Knoche, J; Knox, L; Kunz, M; Kurki-Suonio, H; Lagache, G; Lähteenmäki, A; Lamarre, J -M; Lasenby, A; Laureijs, R J; Lawrence, C R; Leonardi, R; León-Tavares, J; Lesgourgues, J; Levrier, F; Liguori, M; Lilje, P B; Linden-Vørnle, M; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; Maffei, B; Maino, D; Mandolesi, N; Maris, M; Marshall, D J; Martin, P G; Martínez-González, E; Masi, S; Massardi, M; Matarrese, S; Matthai, F; Mazzotta, P; McGehee, P; Melchiorri, A; Mendes, L; Mennella, A; Migliaccio, M; Mitra, S; Miville-Deschênes, M -A; Moneti, A; Montier, L; Morgante, G; Mortlock, D; Munshi, D; Murphy, J A; Naselsky, P; Nati, F; Natoli, P; Netterfield, C B; Nørgaard-Nielsen, H U; Noviello, F; Novikov, D; Novikov, I; Osborne, S; Oxborrow, C A; Paci, F; Pagano, L; Pajot, F; Paladini, R; Paoletti, D; Pasian, F; Patanchon, G; Perdereau, O; Perotto, L; Perrotta, F; Piacentini, F; Piat, M; Pierpaoli, E; Pietrobon, D; Plaszczynski, S; Pointecouteau, E; Polenta, G; Ponthieu, N; Popa, L; Poutanen, T; Pratt, G W; Prézeau, G; Prunet, S; Puget, J -L; Rachen, J P; Reach, W T; Rebolo, R; Reinecke, M; Remazeilles, M; Renault, C; Ricciardi, S; Riller, T; Ristorcelli, I; Rocha, G; Rosset, C; Roudier, G; Rowan-Robinson, M; Rubiño-Martín, J A; Rusholme, B; Sandri, M; Santos, D; Savini, G; Scott, D; Seiffert, M D; Shellard, E P S; Spencer, L D; Starck, J -L; Stolyarov, V; Stompor, R; Sudiwala, R; Sunyaev, R; Sureau, F; Sutton, D; Suur-Uski, A -S; Sygnet, J -F; Tauber, J A; Tavagnacco, D; Terenzi, L; Toffolatti, L; Tomasi, M; Tristram, M; Tucci, M; Tuovinen, J; Türler, M; Umana, G; Valenziano, L; Valiviita, J; Van Tent, B; Vielva, P; Villa, F; Vittorio, N; Wade, L A; Wandelt, B D; Welikala, N; Yvon, D; Zacchei, A; Zonca, A

    2014-01-01

    This paper presents an all-sky model of dust emission from the Planck 857, 545 and 353 GHz, and IRAS 100 micron data. Using a modified black-body fit to the data we present all-sky maps of the dust optical depth, temperature, and spectral index over the 353-3000 GHz range. This model is a tight representation of the data at 5 arcmin. It shows variations of the order of 30 % compared with the widely-used model of Finkbeiner, Davis, and Schlegel. The Planck data allow us to estimate the dust temperature uniformly over the whole sky, providing an improved estimate of the dust optical depth compared to previous all-sky dust model, especially in high-contrast molecular regions. An increase of the dust opacity at 353 GHz, tau_353/N_H, from the diffuse to the denser interstellar medium (ISM) is reported. It is associated with a decrease in the observed dust temperature, T_obs, that could be due at least in part to the increased dust opacity. We also report an excess of dust emission at HI column densities lower than...

  1. All-Sky Interferometry with Spherical Harmonic Transit Telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, J.Richard [Canadian Inst. Theor. Astrophys.; Sigurdson, Kris [British Columbia U.; Pen, Ue-Li [Canadian Inst. Theor. Astrophys.; Stebbins, Albert [Fermilab; Sitwell, Michael [British Columbia U.

    2013-02-01

    In this paper we describe the spherical harmonic transit telescope, a novel formalism for the analysis of transit radio telescopes. This all-sky approach bypasses the curved sky complications of traditional interferometry and so is particularly well suited to the analysis of wide-field radio interferometers. It enables compact and computationally efficient representations of the data and its statistics that allow new ways of approaching important problems like map-making and foreground removal. In particular, we show how it enables the use of the Karhunen-Loeve transform as a highly effective foreground filter, suppressing realistic foreground residuals for our fiducial example by at least a factor twenty below the 21cm signal even in highly contaminated regions of the sky. This is despite the presence of the angle-frequency mode mixing inherent in real-world instruments with frequency-dependent beams. We show, using Fisher forecasting, that foreground cleaning has little effect on power spectrum constraints compared to hypothetical foreground-free measurements. Beyond providing a natural real-world data analysis framework for 21cm telescopes now under construction and future experiments, this formalism allows accurate power spectrum forecasts to be made that include the interplay of design constraints and realistic experimental systematics with twenty-first century 21cm science.

  2. Optimum Design Parameters of Box Window DSF Office at Different Glazing Types under Sub Interval of Intermediate Sky Conditions (20-40 klux)

    Science.gov (United States)

    Elayeb, O. K.; Alghoul, M. A.; Sopian, K.; Khrita, N. G.

    2017-11-01

    Despite Double skin façade (DSF) buildings are widely deployed worldwide, daylighting strategy is not commonly incorporated in these buildings compare to other strategies. Therefore, further theoretical and experimental studies would lead to adopting daylighting strategy in DSF office buildings. The aim of this study is to investigate the daylighting performance of office building at different design parameters of box window DSF using different glazing types under sub interval of intermediate sky conditions (20-40) klux using the (IES VE) simulation tool from Integrated Environmental Solutions - Virtual Environment. The implemented design parameters are window wall ratio (WWR) of internal façade (10-100) %, cavity depth (CD) of DSF (1-2.5) m and different glazing types. The glazing types were selected from the list available in the (IES VE) simulation tool. After series of evaluations, bronze tinted coating (STOPSOL) is implemented for the exterior façade while clear float, clear reflective coating (STOPSOL), grey and brown tinted coating (Anti-sun float) and blue coating tinted (SUNCOOL float) are implemented for the interior façade. In this paper, several evaluation parameters are used to quantify the optimum design parameters that would balance the daylighting requirements of a box window DSF office versus sky conditions range (20-40) klux. The optimum design parameters of DSF office building obtained under different glazing types are highlighted as follows. When using bronze tinted coating (STOPSOL) for the exterior façade, the glazing types of interior façade that showed superior daylighting performance of DSF office at (CD of 1.0m with WWR of 70%), (CD of 1.5m with WWR of 70%), (CD of 2.0m with WWR of 70%) and (CD of 2.0m with WWR of 70%) are grey tinted coating (Anti-sun float), clear reflective coating (STOPSOL), brown tinted coating (Anti-sun float), and clear float glazing respectively. Blue Coating tinted (SUNCOOL float) of interior façade glazing

  3. Single-footprint retrievals for AIRS using a fast TwoSlab cloud-representation model and the SARTA all-sky infrared radiative transfer algorithm

    Science.gov (United States)

    DeSouza-Machado, Sergio; Larrabee Strow, L.; Tangborn, Andrew; Huang, Xianglei; Chen, Xiuhong; Liu, Xu; Wu, Wan; Yang, Qiguang

    2018-01-01

    One-dimensional variational retrievals of temperature and moisture fields from hyperspectral infrared (IR) satellite sounders use cloud-cleared radiances (CCRs) as their observation. These derived observations allow the use of clear-sky-only radiative transfer in the inversion for geophysical variables but at reduced spatial resolution compared to the native sounder observations. Cloud clearing can introduce various errors, although scenes with large errors can be identified and ignored. Information content studies show that, when using multilayer cloud liquid and ice profiles in infrared hyperspectral radiative transfer codes, there are typically only 2-4 degrees of freedom (DOFs) of cloud signal. This implies a simplified cloud representation is sufficient for some applications which need accurate radiative transfer. Here we describe a single-footprint retrieval approach for clear and cloudy conditions, which uses the thermodynamic and cloud fields from numerical weather prediction (NWP) models as a first guess, together with a simple cloud-representation model coupled to a fast scattering radiative transfer algorithm (RTA). The NWP model thermodynamic and cloud profiles are first co-located to the observations, after which the N-level cloud profiles are converted to two slab clouds (TwoSlab; typically one for ice and one for water clouds). From these, one run of our fast cloud-representation model allows an improvement of the a priori cloud state by comparing the observed and model-simulated radiances in the thermal window channels. The retrieval yield is over 90 %, while the degrees of freedom correlate with the observed window channel brightness temperature (BT) which itself depends on the cloud optical depth. The cloud-representation and scattering package is benchmarked against radiances computed using a maximum random overlap (RMO) cloud scheme. All-sky infrared radiances measured by NASA's Atmospheric Infrared Sounder (AIRS) and NWP thermodynamic and cloud

  4. Single-footprint retrievals for AIRS using a fast TwoSlab cloud-representation model and the SARTA all-sky infrared radiative transfer algorithm

    Directory of Open Access Journals (Sweden)

    S. DeSouza-Machado

    2018-01-01

    Full Text Available One-dimensional variational retrievals of temperature and moisture fields from hyperspectral infrared (IR satellite sounders use cloud-cleared radiances (CCRs as their observation. These derived observations allow the use of clear-sky-only radiative transfer in the inversion for geophysical variables but at reduced spatial resolution compared to the native sounder observations. Cloud clearing can introduce various errors, although scenes with large errors can be identified and ignored. Information content studies show that, when using multilayer cloud liquid and ice profiles in infrared hyperspectral radiative transfer codes, there are typically only 2–4 degrees of freedom (DOFs of cloud signal. This implies a simplified cloud representation is sufficient for some applications which need accurate radiative transfer. Here we describe a single-footprint retrieval approach for clear and cloudy conditions, which uses the thermodynamic and cloud fields from numerical weather prediction (NWP models as a first guess, together with a simple cloud-representation model coupled to a fast scattering radiative transfer algorithm (RTA. The NWP model thermodynamic and cloud profiles are first co-located to the observations, after which the N-level cloud profiles are converted to two slab clouds (TwoSlab; typically one for ice and one for water clouds. From these, one run of our fast cloud-representation model allows an improvement of the a priori cloud state by comparing the observed and model-simulated radiances in the thermal window channels. The retrieval yield is over 90 %, while the degrees of freedom correlate with the observed window channel brightness temperature (BT which itself depends on the cloud optical depth. The cloud-representation and scattering package is benchmarked against radiances computed using a maximum random overlap (RMO cloud scheme. All-sky infrared radiances measured by NASA's Atmospheric Infrared Sounder (AIRS and NWP

  5. Comparison of seven optical clearing methods for mouse brain

    Science.gov (United States)

    Wan, Peng; Zhu, Jingtan; Yu, Tingting; Zhu, Dan

    2018-02-01

    Recently, a variety of tissue optical clearing techniques have been developed to reduce light scattering for imaging deeper and three-dimensional reconstruction of tissue structures. Combined with optical imaging techniques and diverse labeling methods, these clearing methods have significantly promoted the development of neuroscience. However, most of the protocols were proposed aiming for specific tissue type. Though there are some comparison results, the clearing methods covered are limited and the evaluation indices are lack of uniformity, which made it difficult to select a best-fit protocol for clearing in practical applications. Hence, it is necessary to systematically assess and compare these clearing methods. In this work, we evaluated the performance of seven typical clearing methods, including 3DISCO, uDISCO, SeeDB, ScaleS, ClearT2, CUBIC and PACT, on mouse brain samples. First, we compared the clearing capability on both brain slices and whole-brains by observing brain transparency. Further, we evaluated the fluorescence preservation and the increase of imaging depth. The results showed that 3DISCO, uDISCO and PACT posed excellent clearing capability on mouse brains, ScaleS and SeeDB rendered moderate transparency, while ClearT2 was the worst. Among those methods, ScaleS was the best on fluorescence preservation, and PACT achieved the highest increase of imaging depth. This study is expected to provide important reference for users in choosing most suitable brain optical clearing method.

  6. 78 FR 32287 - Self-Regulatory Organizations; ICE Clear Europe Limited; Notice of Filing of Proposed Rule Change...

    Science.gov (United States)

    2013-05-29

    ... Guaranty Fund in accordance with the risk waterfall under the Rules, the energy segment will be applied... algorithm,\\5\\ with modifications for concentration charges and a trinomial model used with respect to... of the LIFFE A&M clearing relationship. Relevant models applicable to the clearing of LIFFE Contracts...

  7. The impact of instrument field of view on measurements of cloudy-sky spectral radiances from space: application to IRIS and IMG

    Energy Technology Data Exchange (ETDEWEB)

    Brindley, H.E. E-mail: h.brindley@ic.ac.uk; Harries, J.E

    2003-05-15

    Spatially resolved images from the MODerate Resolution Imaging Spectrometer (MODIS) instrument are used to investigate the impact of a change in spatial field of view, from that typical of the Nimbus 4 Infrared Interferometer Spectrometer (IRIS) to that of the Interferometric Monitor for Greenhouse Gases (IMG), upon the spectral outgoing longwave radiation (OLR). Considering all-sky conditions it is found that for a typical tropical scene, approximately 150 paired measurements are required to obtain agreement to within {+-}2 K in the average brightness temperature (T{sub B}), in the most transparent window channels. At mid-latitudes, the reduced scene variability means that fewer observations are required to meet the same criterion. For clear- and cloudy-sky separation a simple threshold technique based on the window T{sub B} and underlying sea-surface temperature tends to result in a systematic underestimate of the average cloudy T{sub B} by the larger field of view. A better estimate can be obtained by applying a double threshold to discriminate against the most mixed scenes.

  8. Determination of the sun area in sky camera images using radiometric data

    International Nuclear Information System (INIS)

    Alonso, J.; Batlles, F.J.; Villarroel, C.; Ayala, Rosa; Burgaleta, J.I.

    2014-01-01

    Highlights: • We have developed a model for the determination of solar area on sky camera imagery. • An estimation of direct normal irradiance is given for cloudless sky. • The presented model resolves the problem of saturation of pixels in the solar area. • The model allows to identify clouds in the solar area of sky camera imagery. • Developed model has an 92% of agreement between processed and observed images. - Abstract: Due to the increasing development and expansion of solar power plants, it is necessary to have complete and absolute knowledge of all factors and occurrences that can affect the dynamics and quality of their production. The importance of clouds in the attenuation of solar radiation is a transcendental and decisive factor in the incident energy from the sun. Detecting clouds with sky cameras is a very problematic issue. The captured solar area in the images exhibits a pronounced saturation of pixels as a consequence of sunlight penetration and the appearance of various atmospheric features. The present article reports a methodology based on radiometric data that is used to determine the causes of saturation in the solar zone and its vicinity on images from a TSI-880 model sky camera. The correct method identifies the presence or absence of clouds in the saturated zone with 92% success

  9. 75 FR 62899 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Order Approving Proposed Rule...

    Science.gov (United States)

    2010-10-13

    ... criteria specified in the Financial Accounting Standards Board's Interpretation No. 39, Offsetting of... Clarity With Respect to the Close Out Netting of the Government Securities Division in the Event of the Fixed Income Clearing Corporation's Default or Insolvency October 5, 2010. I. Introduction On August 12...

  10. A Comprehensive Approach to Dark Skies Research and Education at NOAO

    Science.gov (United States)

    Walker, Constance E.; Pompea, S. M.; Sparks, R. T.

    2013-01-01

    NOAO and its Education and Public Outreach group play an important role locally, nationally, and internationally in raising dark skies awareness. For the past 3 years NOAO has co-hosted the international “Earth and Sky” photo contest. In 2012 there were over 600 entries contributed within 3 weeks. NOAO also created a series of audio podcasts based on serial-type skits featuring a caped dark-skies hero who typically “saves the night” by mitigating upward directed lights with shields, thereby saving sea turtles, minimizing health effects, conserving energy, or keeping the public safe. To help understand the effects of light pollution, a citizen-science campaign called GLOBE at Night was started seven years ago. The worldwide campaign involves the public in recording night sky brightness data by matching the view of a constellation like Orion with maps of progressively fainter stars. Every year, NOAO adds more opportunities for participation: more campaigns during the year, Web applications for smart phones, objective measurements with sky brightness meters, and a GLOBE at Night Facebook page. Campaigns will run roughly the first 10 days of January through May in 2013. The EPO group created “Dark Skies Rangers”, a suite of well-tested and evaluated hands-on, minds-on activities that have children building star-brightness “readers,” creating glow-in-the-dark tracings to visualize constellations, and role-playing confused sea turtles. They also created a model city with shielded lights to stop upward light, examine different kinds of bulbs for energy efficiency, and perform an outdoor lighting audit of their school or neighborhood to determine ways to save energy. In the REU program at NOAO North, the undergraduate students have been doing research over the last 3 summers on effect of light pollution on endangered bats and characterizing the behavior of sky brightness over time across Tucson and on nearby astronomical mountaintops. For more information

  11. Sky subtraction at the Poisson limit with fibre-optic multiobject spectroscopy

    Science.gov (United States)

    Sharp, R.; Parkinson, H.

    2010-11-01

    We report on the limitations of sky-subtraction accuracy for long-duration fibre-optic multiobject spectroscopy of faint astronomical sources during long-duration exposures. We show that while standard sky subtraction techniques yield accuracies consistent with the Poisson noise limit for exposures of 1h duration, there are large-scale systematic defects that inhibit the sensitivity gains expected on the summation of longer duration exposures. For the AAOmega system at the Anglo-Australian Telescope, we identify a limiting systematic sky-subtraction accuracy, which is reached after integration times of 4-10h. We show that these systematic defects can be avoided through the use of the fibre nod-and-shuffle (N+S) observing mode, but with a potential cost in observing efficiency. Finally, we demonstrate that these disadvantages can be overcome through the application of a Principal Components Analysis (PCA) sky-subtraction routine. Such an approach minimize systematic residuals across long-duration exposures, allowing deep integrations. We apply the PCA approach to over 200h of on-sky observations and conclude that for the AAOmega system, the residual error in long-duration observations falls at a rate proportional to τ-0.32 in contrast to the τ-0.5 rate expected from theoretical considerations. With this modest rate of decline, the PCA approach represents a more efficient mode of observation than the N+S technique for observations in the sky limited regime with durations of 10-100h (even before accounting for the additional signal-to-noise ratio and targeting efficiency losses often associated with the N+S technique). This conclusion has important implications for the observing strategies of the next generation of fibre-optics redshift surveys with existing facilities as well as design implications for fibre-optic systems destined for new facilities. It argues against the use of the inherently inefficient N+S technique for faint object fibre-optic survey

  12. A Multi-Polarization Study on Ship Detection over X-Band Full-Resolution COSMO SkyMed SAR Data

    Science.gov (United States)

    Migliaccio, Maurizio; Nunziata, Ferdinando; Sorrentio, Antonio; Ferrara, Giuseppe

    2011-03-01

    Ship detection over marine Synthetic Aperture Radar (SAR) images is a key application for global monitoring for environment and security. In this paper, a physically-based filter which exploits a proper combination of GK parameters is conceived to unambiguously observe ships over sea surface in HV-polarized Single Look Complex (SLC) SAR data. Experiments accomplished over a meaningful set of X-band SLC CosmoSkyMed StripMap SAR data confirm the physical soundness of the proposed approach.

  13. Measuring the color and brightness of artificial sky glow from cities using an all-sky imaging system calibrated with astronomical methods in the Johnson-Cousins B and V photometric systems

    Science.gov (United States)

    Pipkin, Ashley; Duriscoe, Dan M.; Lughinbuhl, Christian

    2017-01-01

    Artificial light at night, when observed at some distance from a city, results in a dome of sky glow, brightest at the horizon. The spectral power distribution of electric light utilized will determine its color of the light dome and the amount of light will determine its brightness. Recent outdoor lighting technologies have included blue-rich light emitting diode (LED) sources that may increase the relative amount of blue to green light in sky glow compared to typical high pressure sodium (HPS) sources with warmer spectra. Measuring and monitoring this effect is important to the preservation of night sky visual quality as seen from undeveloped areas outside the city, such as parks or other protected areas, since the dark-adapted human eye is more sensitive to blue and green. We present a method using a wide field CCD camera which images the entire sky in both Johnson V and B photometric bands. Standard stars within the images are used for calibration. The resulting all-sky brightness maps, and a derived B-V color index map, provide a means to assess and track the impact of specific outdoor lighting practices. We also present example data from several cities, including Las Vegas, Nevada, Flagstaff, Arizona, and Cheyenne, Wyoming.

  14. Between Earth and Sky

    DEFF Research Database (Denmark)

    Carter, Adrian

    2009-01-01

    to rescue architecture from the sterile impasse of late-modernism. In his works the basic elements of lived space become present: the earth, the sky and the `between` of human existence." Jørn Utzon's architecture ranges from the modest to the monumental; from the Kingo courtyard houses, the finest...... of form, material and function, motivated by social values. To this essentially regional response, Utzon combines a fascination for the architectural legacies of foreign cultures. These influences include the architecture of the ancient Mayan civilisation, as well as the Islamic world, China and Japan...

  15. 75 FR 70055 - Self-Regulatory Organizations; The Options Clearing Corporation; Order Approving Proposed Rule...

    Science.gov (United States)

    2010-11-16

    ... accommodate quarterly options, which expire on the last business day of a calendar quarter, and short term options, which expire a week after their introduction for trading. Quarterly index options and short term... And Monthly Options November 9, 2010. I. Introduction On September 15, 2010, The Options Clearing...

  16. 77 FR 60165 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Order Approving Proposed Rule...

    Science.gov (United States)

    2012-10-02

    ... Securities Industry and Financial Markets Association (``SIFMA'') MBS Operations Committee. MBSD advised... safeguarding of securities and funds that are in the custody or control of such clearing agency, or for which... assure the safeguarding of securities and funds in FICC's custody or control, or for which FICC is...

  17. Deep sky observing an astronomical tour

    CERN Document Server

    Coe, Steven R

    2016-01-01

    This updated second edition has all of the information needed for your successful forays into deep sky observing. Coe uses his years of experience to give detailed practical advice about how to find the best observing site, how to make the most of the time spent there, and what equipment and instruments to take along. There are comprehensive lists of deep sky objects of all kinds, along with Steve's own observations describing how they look through telescopes with apertures ranging from 4 inches to 36 inches (0.1 - 0.9 meters). Binocular observing also gets its due, while the lists of objects have been amended to highlight only the best targets. A new index makes finding targets easier than ever before, while the selection of viewing targets has been revised from the first edition. Most of all, this book is all about how to enjoy astronomy. The author's enthusiasm and sense of wonder shine through every page as he invites you along on a tour of some of the most beautiful and fascinating sites in the deep ...

  18. ultra-Stable Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (5STAR)

    Science.gov (United States)

    Dunagan, S. E.; Johnson, R. R.; Redemann, J.; Holben, B. N.; Schmid, B.; Flynn, C. J.; Fahey, L.; LeBlanc, S. E.; Liss, J.; Kacenelenbogen, M. S.; Segal-Rosenhaimer, M.; Shinozuka, Y.; Dahlgren, R. P.; Pistone, K.; Karol, Y.

    2017-12-01

    The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) combines airborne sun tracking and sky scanning with diffraction spectroscopy to improve knowledge of atmospheric constituents and their links to air pollution and climate. Direct beam hyperspectral measurement of optical depth improves retrievals of gas constituents and determination of aerosol properties. Sky scanning enhances retrievals of aerosol type and size distribution. Hyperspectral cloud-transmitted radiance measurements enable the retrieval of cloud properties from below clouds. These measurements tighten the closure between satellite and ground-based measurements. 4STAR incorporates a modular sun-tracking/ sky-scanning optical head with optical fiber signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical tracking head, and future detector evolution. 4STAR has supported a broad range of flight experiments since it was first flown in 2010. This experience provides the basis for a series of improvements directed toward reducing measurement uncertainty and calibration complexity, and expanding future measurement capabilities, to be incorporated into a new 5STAR instrument. A 9-channel photodiode radiometer with AERONET-matched bandpass filters will be incorporated to improve calibration stability. A wide dynamic range tracking camera will provide a high precision solar position tracking signal as well as an image of sky conditions around the solar axis. An ultrasonic window cleaning system design will be tested. A UV spectrometer tailored for formaldehyde and SO2 gas retrievals will be added to the spectrometer enclosure. Finally, expansion capability for a 4 channel polarized radiometer to measure the Stokes polarization vector of sky light will be incorporated. This paper presents initial progress on this next-generation 5STAR instrument. Keywords: atmosphere; climate; pollution; radiometry; technology; hyperspectral; fiber optic

  19. An Investigation of LED Street Lighting's Impact on Sky Glow

    Energy Technology Data Exchange (ETDEWEB)

    Kinzey, Bruce R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Perrin, Tess E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Miller, Naomi J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kocifaj, Miroslav [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Aube, Martin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lamphar, Hector A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-04-25

    A significant amount of public attention has recently focused on perceived impacts of converting street lighting from incumbent lamp-based products to LED technology. Much of this attention pertains to the higher content of short wavelength light (commonly referred to as "blue light") of LEDs and its attendant influences on sky glow (a brightening of the night sky that can interfere with astronomical observation and may be associated with a host of other issues). The complexity of this topic leads to common misunderstandings and misperceptions among the public, and for this reason the U.S. Department of Energy Solid-State Lighting Program embarked on a study of sky glow using a well-established astronomical model to investigate some of the primary factors influencing sky glow. This report details the results of the investigation and attempts to present those results in terms accessible to the general lighting community. The report also strives to put the results into a larger context, and help educate interested readers on various topics relevant to the issues being discussed.

  20. Sirius brightest diamond in the night sky

    CERN Document Server

    Holberg, Jay B

    2007-01-01

    This book describes why Sirius has been regarded as an important fixture of the night sky since the beginnings of history. It also examines the part that Sirius has played in how we came to achieve our current scientific understanding of stars.

  1. Influence of Sky Conditions on Estimation of Photosynthetic Photon Flux Density for Agricultural Ecosystem

    Science.gov (United States)

    Yamashita, M.; Yoshimura, M.

    2018-04-01

    Photosynthetic photon flux density (PPFD: µmol m-2 s-1) is indispensable for plant physiology processes in photosynthesis. However, PPFD is seldom measured, so that PPFD has been estimated by using solar radiation (SR: W m-2) measured in world wide. In method using SR, there are two steps: first to estimate photosynthetically active radiation (PAR: W m-2) by the fraction of PAR to SR (PF) and second: to convert PAR to PPFD using the ratio of quanta to energy (Q / E: µmol J-1). PF and Q/E usually have been used as the constant values, however, recent studies point out that PF and Q / E would not be constants under various sky conditions. In this study, we use the numeric data of sky-conditions factors such cloud cover, sun appearance/hiding and relative sky brightness derived from whole-sky image processing and examine the influences of sky-conditions factors on PF and Q / E of global and diffuse PAR. Furthermore, we discuss our results by comparing with the existing methods.

  2. 78 FR 36797 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Notice of Designation of Longer...

    Science.gov (United States)

    2013-06-19

    ... NYPC. In the proposed rule change, FICC acknowledged that it will have to alter its risk management... rule change so that it has sufficient time to evaluate the risk management implications of the proposed... Division and New York Portfolio Clearing, LLC June 13, 2013. On April 15, 2013, the Fixed Income Clearing...

  3. GLOBE at Night: a Worldwide Citizen-Science Program to Increase Awareness of Light Pollution by Measuring Night Sky Brightness

    Science.gov (United States)

    Walker, C. E.; Pompea, S. M.

    2011-12-01

    The emphasis in the international citizen-science, star-hunting campaign, GLOBE at Night, is in bringing awareness to the public on issues of light pollution. Light pollution threatens not only observatory sites and our "right to starlight", but can affect energy consumption, wildlife and health. GLOBE at Night has successfully reached a few 100,000 citizen-scientists. What has contributed to its success? Foundational resources are available to facilitate the public's participation in promoting dark skies awareness. The GLOBE at Night website explains clearly the simple-to-participate-in 5 step program and offers background information and interactive games on key concepts. To promote the campaign via popular social media, GLOBE at Night created Facebook and Twitter pages. The program has been expanded to include trainings of the general public, but especially educators in schools, museums and science centers, in unique ways. Education kits for dark skies awareness have been distributed at the training workshops. The kit includes material for a light shielding demonstration, a digital Sky Quality Meter and "Dark Skies Rangers" activities. The activities are on how unshielded light wastes energy, how light pollution affects wildlife and how one can participate in a citizen-science star-hunt like GLOBE at Night. To increase participation in the 2011 campaign, children and adults submitted their sky brightness measurements in real time with smart phones or tablets using the web application at www.globeatnight.org/webapp/. With smart phones and tablets, the location, date and time register automatically. For those without smart mobile devices, user-friendly tools on the GLOBE at Night report page were reconfigured to determine latitude and longitude more easily and accurately. As a proto-type for taking multiple measurements, people in Tucson found it easy to adopt a street and take measurements every mile for the length of the street. The grid of measurements

  4. CLEARING MAGNET DESIGN FOR APS-U

    Energy Technology Data Exchange (ETDEWEB)

    Abliz, M.; Grimmer, J.; Jaski, Y.; Westferro, F.; Ramanathan, M.

    2017-06-25

    The Advanced Photon Source is in the process of developing an upgrade (APS-U) of the storage ring. The upgrade will be converting the current double bend achromat (DBA) lattice to a multi-bend achromat (MBA) lattice. In addition, the storage ring will be operated at 6 GeV and 200 mA with regular swap-out injection to keep the stored beam current constant [1]. The swap-out injection will take place with beamline shutters open. For radiation safety to ensure that no electrons can exit the storage ring, a passive method of protecting the beamline and containing the electrons inside the storage ring is proposed. A clearing magnet will be located in all beamline front ends inside the storage ring tunnel. This article will discuss the features and design of the clearing magnet scheme for APS-U.

  5. Reconstruction of MODIS Spectral Reflectance under Cloudy-Sky Condition

    Directory of Open Access Journals (Sweden)

    Bo Gao

    2016-09-01

    Full Text Available Clouds usually cause invalid observations for sensors aboard satellites, which corrupts the spatio-temporal continuity of land surface parameters retrieved from remote sensing data (e.g., MODerate Resolution Imaging Spectroradiometer (MODIS data and prevents the fusing of multi-source remote sensing data in the field of quantitative remote sensing. Based on the requirements of spatio-temporal continuity and the necessity of methods to restore bad pixels, primarily resulting from image processing, this study developed a novel method to derive the spectral reflectance for MODIS band of cloudy pixels in the visual–near infrared (VIS–NIR spectral channel based on the Bidirectional Reflectance Distribution Function (BRDF and multi-spatio-temporal observations. The proposed method first constructs the spatial distribution of land surface reflectance based on the corresponding BRDF and the solar-viewing geometry; then, a geographically weighted regression (GWR is introduced to individually derive the spectral surface reflectance for MODIS band of cloudy pixels. A validation of the proposed method shows that a total root-mean-square error (RMSE of less than 6% and a total R2 of more than 90% are detected, which indicates considerably better precision than those exhibited by other existing methods. Further validation of the retrieved white-sky albedo based on the spectral reflectance for MODIS band of cloudy pixels confirms an RMSE of 3.6% and a bias of 2.2%, demonstrating very high accuracy of the proposed method.

  6. Microscopic dust in the infrared sky

    International Nuclear Information System (INIS)

    Leene, A.; Wesselius, P.

    1985-01-01

    After ten months of observation IRAS (InfraRed Astronomical Satellite) revealed for the first time an infrared sky map. One of its major discovery has been the display of new constituents in Universe: the infrared cirrus which are interstellar clouds constituted of microparticles abounding in carbon. Results and first hypothesis are presented in this article [fr

  7. Simulating the Sky as Seen by the Square Kilometer Array using the MIT Array Performance Simulator (MAPS)

    Science.gov (United States)

    Matthews, Lynn D.; Cappallo, R. J.; Doeleman, S. S.; Fish, V. L.; Lonsdale, C. J.; Oberoi, D.; Wayth, R. B.

    2009-05-01

    The Square Kilometer Array (SKA) is a proposed next-generation radio telescope that will operate at frequencies of 0.1-30 GHz and be 50-100 times more sensitive than existing radio arrays. Meeting the performance goals of this instrument will require innovative new hardware and software developments, a variety of which are now under consideration. Key to evaluating the performance characteristics of proposed SKA designs and testing the feasibility of new data calibration and processing algorithms is the ability to carry out realistic simulations of radio wavelength arrays under a variety of observing conditions. The MIT Array Performance Simulator (MAPS) (http://www.haystack.mit.edu/ast/arrays/maps/index.html) is an observations simulation package designed to achieve this goal. MAPS accepts an input source list or sky model and generates a model visibility set for a user-defined "virtual observatory'', incorporating such factors as array geometry, primary beam shape, field-of-view, and time and frequency resolution. Optionally, effects such as thermal noise, out-of-beam sources, variable station beams, and time/location-dependent ionospheric effects can be included. We will showcase current capabilities of MAPS for SKA applications by presenting results from an analysis of the effects of realistic sky backgrounds on the achievable image fidelity and dynamic range of SKA-like arrays comprising large numbers of small-diameter antennas.

  8. 75 FR 53368 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2010-08-31

    ... of the Fixed Income Clearing Corporation's Default or Insolvency August 26, 2010. Pursuant to Section... netting of the Government Securities Division (``GSD'') in the event of FICC's default or insolvency. II...

  9. 76 FR 17727 - Self-Regulatory Organizations; The Options Clearing Corporation; Order Approving Proposed Rule...

    Science.gov (United States)

    2011-03-30

    ...-settled, European-style options. In the event of a corporate event that eliminates one of the underlying... Options are highly similar to other index options cleared by OCC except for the identity and nature of the... similar corporate event. If the value of an underlying Relative Performance Index ceases to be published...

  10. Mitigation of Volcanic Risk: The COSMO-SkyMed Contribution

    Science.gov (United States)

    Sacco, Patrizia; Daraio, Maria Girolamo; Battagliere, Maria Libera; Coletta, Alessandro

    2015-05-01

    The Italian Space Agency (ASI) promotes Earth Observation (EO) applications related to themes such as the prediction, monitoring, management and mitigation of natural and anthropogenic hazards. The approach generally followed is the development and demonstration of prototype services, using currently available data from space missions, in particular the COSMO-SkyMed (Constellation of Small Satellites for Mediterranean basin observation) mission, which represents the largest Italian investment in Space System for EO and thanks to which Italy plays a key role worldwide. Projects funded by ASI provide the convergence of various national industry expertise, research and institutional reference users. In this context a significant example is represented by the ASI Pilot Projects, recently concluded, dealing with various thematic, such as volcanoes. In this paper a special focus will be addressed to the volcanic risk management and the contribution provided in this field by COSMO-SkyMed satellite constellation during the last years. A comprehensive overview of the various national and international projects using COSMO-SkyMed data for the volcanic risk mitigation will be given, highlighting the Italian contribution provided worldwide in this operational framework.

  11. Confirmation of gastric tube bedside placement with the sky blue method.

    Science.gov (United States)

    Imamura, Takashi; Maeda, Hajime; Kinoshita, Hidetoshi; Shibukawa, Yasuko; Suda, Kiyomi; Fukuda, Yutaka; Goto, Aya; Nagasawa, Katsutoshi

    2014-02-01

    The purpose was to review our experiences and determine if applying the sky blue method is reliable in confirming gastric tube (GT) placement in neonates. The study population consisted of 44 infants (55 placements) who were admitted to the Takeda General Hospital between April 2012 and March 2013 and who required GT exchange. The sky blue method using indigo carmine (IC) was indicated for planned tube exchange only. Diluted IC was injected into the gastric space via the old GT just before the tube exchange. The tube was exchanged using a standard method. Then, we checked whether the diluted IC could be collected through the new GT or not. The reasons for GT placement were a gestational age of sky blue method was considered successful in 52 placements (94.4%), with the remaining 3 placements (5.6%) considered to be failures due to the inability to obtain IC from the gastric space. No adverse events were observed during the tube exchange period. Based on the results, the sky blue method can be considered to be reliable method for the confirmation of GT placement. These results also suggest that the number of radiologic evaluations performed to confirm correct replacement of the GT in infants can be reduced in the future.

  12. ATLAS: A High-cadence All-sky Survey System

    Science.gov (United States)

    Tonry, J. L.; Denneau, L.; Heinze, A. N.; Stalder, B.; Smith, K. W.; Smartt, S. J.; Stubbs, C. W.; Weiland, H. J.; Rest, A.

    2018-06-01

    Technology has advanced to the point that it is possible to image the entire sky every night and process the data in real time. The sky is hardly static: many interesting phenomena occur, including variable stationary objects such as stars or QSOs, transient stationary objects such as supernovae or M dwarf flares, and moving objects such as asteroids and the stars themselves. Funded by NASA, we have designed and built a sky survey system for the purpose of finding dangerous near-Earth asteroids (NEAs). This system, the “Asteroid Terrestrial-impact Last Alert System” (ATLAS), has been optimized to produce the best survey capability per unit cost, and therefore is an efficient and competitive system for finding potentially hazardous asteroids (PHAs) but also for tracking variables and finding transients. While carrying out its NASA mission, ATLAS now discovers more bright (m day cadence. ATLAS discovered the afterglow of a gamma-ray burst independent of the high energy trigger and has released a variable star catalog of 5 × 106 sources. This is the first of a series of articles describing ATLAS, devoted to the design and performance of the ATLAS system. Subsequent articles will describe in more detail the software, the survey strategy, ATLAS-derived NEA population statistics, transient detections, and the first data release of variable stars and transient light curves.

  13. The great canoes in the sky starlore and astronomy of the South Pacific

    CERN Document Server

    Chadwick, Stephen Robert

    2017-01-01

    Presenting spectacular photographs of astronomical objects of the southern sky, all taken by author Stephen Chadwick, this book explores what peoples of the South Pacific see when they look up at the heavens and what they have done with this knowledge. From wives killing brothers to emus rising out of the desert and great canoes in the sky, this book offers the perfect blend of science, tradition and mythology to bring to life the most famous sights in the heavens above the southern hemisphere. The authors place this starlore in the context of contemporary understandings of astronomy. The night sky of southern societies is as rich in culture as it is in stars. Stories, myths and legends based on constellations, heavenly bodies and other night sky phenomena have played a fundamental role in shaping the culture of pre-modern civilizations throughout the world. Such starlore continues to influence societies throughout the Pacific to this day, with cultures throughout the region – from Australia and New Zealand...

  14. Evaluation of Clear-Sky Incoming Radiation Estimating Equations Typically Used in Remote Sensing Evapotranspiration Algorithms

    Directory of Open Access Journals (Sweden)

    Ted W. Sammis

    2013-09-01

    Full Text Available Net radiation is a key component of the energy balance, whose estimation accuracy has an impact on energy flux estimates from satellite data. In typical remote sensing evapotranspiration (ET algorithms, the outgoing shortwave and longwave components of net radiation are obtained from remote sensing data, while the incoming shortwave (RS and longwave (RL components are typically estimated from weather data using empirical equations. This study evaluates the accuracy of empirical equations commonly used in remote sensing ET algorithms for estimating RS and RL radiation. Evaluation is carried out through comparison of estimates and observations at five sites that represent different climatic regions from humid to arid. Results reveal (1 both RS and RL estimates from all evaluated equations well correlate with observations (R2 ≥ 0.92, (2 RS estimating equations tend to overestimate, especially at higher values, (3 RL estimating equations tend to give more biased values in arid and semi-arid regions, (4 a model that parameterizes the diffuse component of radiation using two clearness indices and a simple model that assumes a linear increase of atmospheric transmissivity with elevation give better RS estimates, and (5 mean relative absolute errors in the net radiation (Rn estimates caused by the use of RS and RL estimating equations varies from 10% to 22%. This study suggests that Rn estimates using recommended incoming radiation estimating equations could improve ET estimates.

  15. 77 FR 520 - Self-Regulatory Organizations; Options Clearing Corporation; Order Approving Proposed Rule Change...

    Science.gov (United States)

    2012-01-05

    ... one of the reference ETFs measured by the index is a gold- or silver-based ETF.\\5\\ Generally, OCC... security of an underlying relative performance index is an ETF designed to measure the return of gold or... changes to OCC's By-Laws clarifying that options on the CBOE Gold ETF Volatility Index will be cleared and...

  16. SED16 autonomous star tracker night sky testing

    Science.gov (United States)

    Foisneau, Thierry; Piriou, Véronique; Perrimon, Nicolas; Jacob, Philippe; Blarre, Ludovic; Vilaire, Didier

    2017-11-01

    The SED16 is an autonomous multi-missions star tracker which delivers three axis satellite attitude in an inertial reference frame and the satellite angular velocity with no prior information. The qualification process of this star sensor includes five validation steps using optical star simulator, digitized image simulator and a night sky tests setup. The night sky testing was the final step of the qualification process during which all the functions of the star tracker were used in almost nominal conditions : Autonomous Acquisition of the attitude, Autonomous Tracking of ten stars. These tests were performed in Calern in the premises of the OCA (Observatoire de la Cote d'Azur). The test set-up and the test results are described after a brief review of the sensor main characteristics and qualification process.

  17. DESCQA: Synthetic Sky Catalog Validation Framework

    Science.gov (United States)

    Mao, Yao-Yuan; Uram, Thomas D.; Zhou, Rongpu; Kovacs, Eve; Ricker, Paul M.; Kalmbach, J. Bryce; Padilla, Nelson; Lanusse, François; Zu, Ying; Tenneti, Ananth; Vikraman, Vinu; DeRose, Joseph

    2018-04-01

    The DESCQA framework provides rigorous validation protocols for assessing the quality of high-quality simulated sky catalogs in a straightforward and comprehensive way. DESCQA enables the inspection, validation, and comparison of an inhomogeneous set of synthetic catalogs via the provision of a common interface within an automated framework. An interactive web interface is also available at portal.nersc.gov/project/lsst/descqa.

  18. 78 FR 56953 - Self-Regulatory Organizations; The Options Clearing Corporation; Notice of Filing of an Advance...

    Science.gov (United States)

    2013-09-16

    ... disapprove as margin collateral for a particular clearing member, shares of an otherwise eligible security... members with respect to a specific security. OCC proposes to address the risk presented by concentrated... such clearing member's accounts. OCC proposes to enhance its ability to limit its risk exposure to a...

  19. Internet compromise clears way for WSIS agreement

    CERN Multimedia

    Ermert, M

    2003-01-01

    A working group under the leadership of United Nations Secretary General Kofi Annan himself will try to resolve the deep differences on the question of Internet governance, officials said here. The group, whose exact membership wasn't immediately clear, is to propose a solution to the controversial issue that has given negotiators at the World Summit of the Information Society (WSIS) a headache (1/2 page).

  20. The Catalina Sky Survey for Near-Earth Objects

    Science.gov (United States)

    Christensen, E.

    The Catalina Sky Survey (CSS) specializes in the detection of the closest transients in our transient universe: near-Earth objects (NEOs). CSS is the leading NEO survey program since 2005, with a discovery rate of 500-600 NEOs per year. This rate is set to substantially increase starting in 2014 with the deployment of wider FOV cameras at both survey telescopes, while a proposed 3-telescope system in Chile would provide a new and significant capability in the Southern Hemisphere beginning as early as 2015. Elements contributing to the success of CSS may be applied to other surveys, and include 1) Real-time processing, identification, and reporting of interesting transients; 2) Human-assisted validation to ensure a clean transient stream that is efficient to the limits of the system (˜ 1σ); 3) an integrated follow-up capability to ensure threshold or high-priority transients are properly confirmed and followed up. Additionally, the open-source nature of the CSS data enables considerable secondary science (i.e. CRTS), and CSS continues to pursue collaborations to maximize the utility of the data.

  1. ESO unveils an amazing, interactive, 360-degree panoramic view of the entire night sky

    Science.gov (United States)

    2009-09-01

    The first of three images of ESO's GigaGalaxy Zoom project - a new magnificent 800-million-pixel panorama of the entire sky as seen from ESO's observing sites in Chile - has just been released online. The project allows stargazers to explore and experience the Universe as it is seen with the unaided eye from the darkest and best viewing locations in the world. This 360-degree panoramic image, covering the entire celestial sphere, reveals the cosmic landscape that surrounds our tiny blue planet. This gorgeous starscape serves as the first of three extremely high-resolution images featured in the GigaGalaxy Zoom project, launched by ESO within the framework of the International Year of Astronomy 2009 (IYA2009). GigaGalaxy Zoom features a web tool that allows users to take a breathtaking dive into our Milky Way. With this tool users can learn more about many different and exciting objects in the image, such as multicoloured nebulae and exploding stars, just by clicking on them. In this way, the project seeks to link the sky we can all see with the deep, "hidden" cosmos that astronomers study on a daily basis. The wonderful quality of the images is a testament to the splendour of the night sky at ESO's sites in Chile, which are the most productive astronomical observatories in the world. The plane of our Milky Way Galaxy, which we see edge-on from our perspective on Earth, cuts a luminous swath across the image. The projection used in GigaGalaxy Zoom place the viewer in front of our Galaxy with the Galactic Plane running horizontally through the image - almost as if we were looking at the Milky Way from the outside. From this vantage point, the general components of our spiral galaxy come clearly into view, including its disc, marbled with both dark and glowing nebulae, which harbours bright, young stars, as well as the Galaxy's central bulge and its satellite galaxies. The painstaking production of this image came about as a collaboration between ESO, the renowned

  2. Automatic Mosaicking of Satellite Imagery Considering the Clouds

    Science.gov (United States)

    Kang, Yifei; Pan, Li; Chen, Qi; Zhang, Tong; Zhang, Shasha; Liu, Zhang

    2016-06-01

    With the rapid development of high resolution remote sensing for earth observation technology, satellite imagery is widely used in the fields of resource investigation, environment protection, and agricultural research. Image mosaicking is an important part of satellite imagery production. However, the existence of clouds leads to lots of disadvantages for automatic image mosaicking, mainly in two aspects: 1) Image blurring may be caused during the process of image dodging, 2) Cloudy areas may be passed through by automatically generated seamlines. To address these problems, an automatic mosaicking method is proposed for cloudy satellite imagery in this paper. Firstly, modified Otsu thresholding and morphological processing are employed to extract cloudy areas and obtain the percentage of cloud cover. Then, cloud detection results are used to optimize the process of dodging and mosaicking. Thus, the mosaic image can be combined with more clear-sky areas instead of cloudy areas. Besides, clear-sky areas will be clear and distortionless. The Chinese GF-1 wide-field-of-view orthoimages are employed as experimental data. The performance of the proposed approach is evaluated in four aspects: the effect of cloud detection, the sharpness of clear-sky areas, the rationality of seamlines and efficiency. The evaluation results demonstrated that the mosaic image obtained by our method has fewer clouds, better internal color consistency and better visual clarity compared with that obtained by traditional method. The time consumed by the proposed method for 17 scenes of GF-1 orthoimages is within 4 hours on a desktop computer. The efficiency can meet the general production requirements for massive satellite imagery.

  3. 77 FR 74283 - Clearing Requirement Determination Under Section 2(h) of the CEA

    Science.gov (United States)

    2012-12-13

    ... cleared through central counterparties and traded on exchanges or electronic trading platforms, where... currency non-deliverable forwards to meet its proposed mandatory clearing criteria. Additional swaps will... Reserve System; (iii) the Office of the Comptroller of the Currency; and (iv) the Federal Deposit...

  4. Analýza sortimentu firmy SkyTech Corporation s.r.o.

    OpenAIRE

    Dvořáková, Šárka

    2017-01-01

    This thesis focuses on small company SkyTech Corporation s.r.o, which distributes products from the field of cosmetic, decorative cosmetic, cosmetic accessories and make-up brushes. The first part is theoretical and serves as basis for elaboration of the practical part. Theoretical part focus on marketing mix, competition, assortment and analysis connected with them. In practical part SkyTech Corporaton s.r.o. is introduced. Than follows the evaluation of individual brands and their roles in ...

  5. Advertising Citizen Science: A Trailer for the Citizen Sky Project

    Science.gov (United States)

    Wyatt, Ryan; Price, A.

    2012-01-01

    Citizen Sky is a multi-year, NSF funded citizen science project involving the bright and mysterious variable star epsilon Aurigae. The project was conceived by the IYA 2009 working group on Research Experiences for Students, Teachers, and Citizen-Scientists. Citizen Sky goes beyond simple observing to include a major data analysis component, introducing participants to the full scientific process from background research to paper writing for a peer-reviewed journal. As a means of generating interest in the project, the California Academy of Sciences produced a six-minute "trailer” formatted for both traditional and fulldome planetariums as well as HD and web applications. This talk will review the production process for the trailer as well as the methods of distribution via planetariums, social media, and other venues_along with an update on the Citizen Sky Project as a whole. We will show how to use a small, professionally-produced planetarium trailer to help spread word on a citizen science project. We will also show preliminary results on a study about how participation level/type in the project affects science learning.

  6. IMPROVED BACKGROUND SUBTRACTION FOR THE SLOAN DIGITAL SKY SURVEY IMAGES

    International Nuclear Information System (INIS)

    Blanton, Michael R.; Kazin, Eyal; Muna, Demitri; Weaver, Benjamin A.; Price-Whelan, Adrian

    2011-01-01

    We describe a procedure for background subtracting Sloan Digital Sky Survey (SDSS) imaging that improves the resulting detection and photometry of large galaxies on the sky. Within each SDSS drift scan run, we mask out detected sources and then fit a smooth function to the variation of the sky background. This procedure has been applied to all SDSS-III Data Release 8 images, and the results are available as part of that data set. We have tested the effect of our background subtraction on the photometry of large galaxies by inserting fake galaxies into the raw pixels, reanalyzing the data, and measuring them after background subtraction. Our technique results in no size-dependent bias in galaxy fluxes up to half-light radii r 50 ∼ 100 arcsec; in contrast, for galaxies of that size the standard SDSS photometric catalog underestimates fluxes by about 1.5 mag. Our results represent a substantial improvement over the standard SDSS catalog results and should form the basis of any analysis of nearby galaxies using the SDSS imaging data.

  7. The red-sky enigma over Svalbard in December 2002

    Directory of Open Access Journals (Sweden)

    F. Sigernes

    2005-07-01

    Full Text Available On 6 December 2002, during winter darkness, an extraordinary event occurred in the sky, as viewed from Longyearbyen (78° N, 15° E, Svalbard, Norway. At 07:30 UT the southeast sky was surprisingly lit up in a deep red colour. The light increased in intensity and spread out across the sky, and at 10:00 UT the illumination was observed to reach the zenith. The event died out at about 12:30 UT. Spectral measurements from the Auroral Station in Adventdalen confirm that the light was scattered sunlight. Even though the Sun was between 11.8 and 14.6deg below the horizon during the event, the measured intensities of scattered light on the southern horizon from the scanning photometers coincided with the rise and setting of the Sun. Calculations of actual heights, including refraction and atmospheric screening, indicate that the event most likely was scattered solar light from a target below the horizon. This is also confirmed by the OSIRIS instrument on board the Odin satellite. The deduced height profile indicates that the scattering target is located 18–23km up in the stratosphere at a latitude close to 73–75° N, southeast of Longyearbyen. The temperatures in this region were found to be low enough for Polar Stratospheric Clouds (PSC to be formed. The target was also identified as PSC by the LIDAR systems at the Koldewey Station in Ny-Ålesund (79° N, 12° E. The event was most likely caused by solar illuminated type II Polar Stratospheric Clouds that scattered light towards Svalbard. Two types of scenarios are presented to explain how light is scattered. Keywords. Atmospheric composition and structure (Transmissions and scattering of radiation; Middle atmospherecomposition and chemistry; Instruments and techniques – History of geophysics (Atmospheric Sciences; The red-sky phenomena

  8. Computer analysis of digital sky surveys using citizen science and manual classification

    Science.gov (United States)

    Kuminski, Evan; Shamir, Lior

    2015-01-01

    As current and future digital sky surveys such as SDSS, LSST, DES, Pan-STARRS and Gaia create increasingly massive databases containing millions of galaxies, there is a growing need to be able to efficiently analyze these data. An effective way to do this is through manual analysis, however, this may be insufficient considering the extremely vast pipelines of astronomical images generated by the present and future surveys. Some efforts have been made to use citizen science to classify galaxies by their morphology on a larger scale than individual or small groups of scientists can. While these citizen science efforts such as Zooniverse have helped obtain reasonably accurate morphological information about large numbers of galaxies, they cannot scale to provide complete analysis of billions of galaxy images that will be collected by future ventures such as LSST. Since current forms of manual classification cannot scale to the masses of data collected by digital sky surveys, it is clear that in order to keep up with the growing databases some form of automation of the data analysis will be required, and will work either independently or in combination with human analysis such as citizen science. Here we describe a computer vision method that can automatically analyze galaxy images and deduce galaxy morphology. Experiments using Galaxy Zoo 2 data show that the performance of the method increases as the degree of agreement between the citizen scientists gets higher, providing a cleaner dataset. For several morphological features, such as the spirality of the galaxy, the algorithm agreed with the citizen scientists on around 95% of the samples. However, the method failed to analyze some of the morphological features such as the number of spiral arms, and provided accuracy of just ~36%.

  9. A methodology for sunlight urban planning: a computer-based solar and sky vault obstruction analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Fernando Oscar Ruttkay; Silva, Carlos Alejandro Nome [Federal Univ. of Santa Catarina (UFSC), Dept. of Architecture and Urbanism, Florianopolis, SC (Brazil); Turkienikz, Benamy [Federal Univ. of Rio Grande do Sul (UFRGS), Faculty of Architecture, Porto Alegre, RS (Brazil)

    2001-07-01

    The main purpose of the present study is to describe a planning methodology to improve the quality of the built environment based on the rational control of solar radiation and the view of the sky vault. The main criterion used to control the access and obstruction of solar radiation was the concept of desirability and undesirability of solar radiation. A case study for implementing the proposed methodology is developed. Although needing further developments to find its way into regulations and practical applications, the methodology has shown a strong potential to deal with an aspect that otherwise would be almost impossible. (Author)

  10. Intercomparisons of nine sky brightness detectors.

    Science.gov (United States)

    den Outer, Peter; Lolkema, Dorien; Haaima, Marty; van der Hoff, Rene; Spoelstra, Henk; Schmidt, Wim

    2011-01-01

    Nine Sky Quality Meters (SQMs) have been intercompared during a night time measurement campaign held in the Netherlands in April 2011. Since then the nine SQMs have been distributed across The Netherlands and form the Dutch network for monitoring night sky brightness. The goal of the intercomparison was to infer mutual calibration factors and obtain insight into the variability of the SQMs under different meteorological situations. An ensemble average is built from the individual measurements and used as a reference to infer the mutual calibration factors. Data required additional synchronization prior to the calibration determination, because the effect of moving clouds combined with small misalignments emerges as time jitter in the measurements. Initial scatter of the individual instruments lies between ±14%. Individual night time sums range from -16% to +20%. Intercalibration reduces this to 0.5%, and -7% to +9%, respectively. During the campaign the smallest luminance measured was 0.657 ± 0.003 mcd/m(2) on 12 April, and the largest value was 5.94 ± 0.03 mcd/m(2) on 2 April. During both occurrences interfering circumstances like snow cover or moonlight were absent.

  11. Intercomparisons of Nine Sky Brightness Detectors

    Directory of Open Access Journals (Sweden)

    Henk Spoelstra

    2011-10-01

    Full Text Available Nine Sky Quality Meters (SQMs have been intercompared during a night time measurement campaign held in the Netherlands in April 2011. Since then the nine SQMs have been distributed across the Netherlands and form the Dutch network for monitoring night sky brightness. The goal of the intercomparison was to infer mutual calibration factors and obtain insight into the variability of the SQMs under different meteorological situations. An ensemble average is built from the individual measurements and used as a reference to infer the mutual calibration factors. Data required additional synchronization prior to the calibration determination, because the effect of moving clouds combined with small misalignments emerges as time jitter in the measurements. Initial scatter of the individual instruments lies between ±14%. Individual night time sums range from −16% to +20%. Intercalibration reduces this to 0.5%, and −7% to +9%, respectively. During the campaign the smallest luminance measured was 0.657 ± 0.003 mcd/m2 on 12 April, and the largest value was 5.94 ± 0.03 mcd/m2 on 2 April. During both occurrences interfering circumstances like snow cover or moonlight were absent.

  12. The Effects of Lamp Spectral Distribution on Sky Glow over Observatories

    Science.gov (United States)

    2015-01-01

    overhead sky glow as a function of distance up to 300 km, from a variety of lamp types, including common gas discharge lamps and several types of LED...distance up to 300 km, from a variety of lamp types, in- cluding common gas discharge lamps and several types of LED lamps . We conclude for both...MAR 2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE The Effects of Lamp Spectral Distribution on Sky Glow

  13. The urban astronomer's guide a walking tour of the cosmos for city sky watchers

    CERN Document Server

    Mollise, Rod

    2006-01-01

    This book covers the "why," "how," and "what" of astronomy under light-polluted skies. It is aimed at urban astronomers and showcases the countless objects - galaxies, nebulae, and star clusters - that can be seen in even in heavily light polluted urban skies.

  14. A Sea-Sky Line Detection Method for Unmanned Surface Vehicles Based on Gradient Saliency.

    Science.gov (United States)

    Wang, Bo; Su, Yumin; Wan, Lei

    2016-04-15

    Special features in real marine environments such as cloud clutter, sea glint and weather conditions always result in various kinds of interference in optical images, which make it very difficult for unmanned surface vehicles (USVs) to detect the sea-sky line (SSL) accurately. To solve this problem a saliency-based SSL detection method is proposed. Through the computation of gradient saliency the line features of SSL are enhanced effectively, while other interference factors are relatively suppressed, and line support regions are obtained by a region growing method on gradient orientation. The SSL identification is achieved according to region contrast, line segment length and orientation features, and optimal state estimation of SSL detection is implemented by introducing a cubature Kalman filter (CKF). In the end, the proposed method is tested on a benchmark dataset from the "XL" USV in a real marine environment, and the experimental results demonstrate that the proposed method is significantly superior to other state-of-the-art methods in terms of accuracy rate and real-time performance, and its accuracy and stability are effectively improved by the CKF.

  15. Can You See the Stars? Citizen-Science Programs to Measure Night Sky Brightness

    Science.gov (United States)

    Walker, Constance E.

    2009-05-01

    For the IYA2009 Dark Skies Awareness Cornerstone Project, partners in dark-sky, astronomy and environmental education are promoting three citizen-scientist programs that measure light pollution at local levels worldwide. These programs take the form of "star hunts", providing people with fun and direct ways to acquire heightened awareness about light pollution through first-hand observations of the night sky. Together the programs are spanning the entire IYA, namely: GLOBE at Night in March, Great World Wide Star Count in October, and How Many Stars during the rest of the year. Citizen-scientists - students, educators, amateur astronomers and the general public - measure the darkness of their local skies and contribute observations online to a world map. Anyone anywhere anytime can look within particular constellations for the faintest stars and match them to one of seven star maps. For more precise measurements, digital sky-brightness meters can be used. Measurements, along with the measurement location, time, and date, are submitted online, and within a few days to weeks a world map showing results is available. These measurements can be compared with data from previous years, as well as with satellite data, population densities, and electrical power-usage maps. Measurements are available online via Google Earth or other tools and as downloadable datasets. Data from multiple locations in one city or region are especially interesting, and can be used as the basis of a class project or science fair experiment, or even to inform the development of public policy. In the last few years these programs successfully conducted campaigns in which more than 35,000 observations were submitted from over 100 countries. The presentation will provide an update, describe how people can become involved and take a look ahead at the program's sustainability. For further information about these and other Dark Skies Awareness programs, please visit www.darkskiesawareness.org.

  16. Clear retainer

    Directory of Open Access Journals (Sweden)

    Priyakorn Chaimongkol

    2017-01-01

    Full Text Available A clear retainer is a removable retainer that is popular in the present day. Compared with conventional fixed and removable orthodontic retainers, it is a more esthetic, comfortable, and inexpensive appliance. Although several studies have been published about clear retainers, it could be difficult to interpret the results because of the variety of study designs, sample sizes, and research methods. This article is intended to compile the content from previous studies and discuss advantages, disadvantages, fabrication, insertion, and adjustment. Moreover, the effectiveness in maintaining dental position, occlusion, retention protocols, thickness, and survival rate of clear retainers is discussed.

  17. Flying in Clear Skies: Technical Arguments Influencing ANAC Regulations

    Directory of Open Access Journals (Sweden)

    Marcello Fragano Baird

    2014-08-01

    Full Text Available Regulatory agencies possess the particularity of being controlled by non-elected politicians whose power is derived from delegations made by incumbent powers. There exists, however, a concern with the creation of institutional mechanisms that permit public participation, thus guaranteeing greater democratization and social control of the regulatory process. One of these participatory mechanisms is the public hearing, which was not given much attention by Brazilian literature on lobbying and interest groups. This article seeks to contribute to fill this gap, focusing on the impact of interest groups acting upon the National Civil Aviation Agency, ANAC. Analyzing comments sent to the public hearings, we identified the commentators and the intensity of their participation, the impact of their efforts as measured by the rate of comment incorporation, and we explained why some comments are incorporated and others are not. We organized an original data base of the comments made at all ANAC public hearings between 2007 and May 2012. We analyzed 518 comments concerning 48 regulations. To test participant influence, we classified the comments by degree of technicality, economic or legal argument, authorship, and request for regulation. To understand the incorporation process, we used regression models through which we presented evidence that a comment's incorporation is directly related to its degree of technicality. Technical comments, which effectively subsidize the resolution, have a higher chance of being incorporated. Even more than corporate power or its force of participation, the technical quality proved to be the main factor for comment incorporation.

  18. Forecast for nuclear energy: Clear skies or stormy weather?

    Science.gov (United States)

    Ferguson, Charles D.

    2018-01-01

    During the last decade many people in the nuclear industry were forecasting a renaissance in construction of nuclear power plants, especially in light of the near-zero greenhouse gas emissions of nuclear power and the global need for such cleaner electricity sources. While the accident in March 2011 at the Fukushima Daiichi Nuclear Power Station in Japan resulted in dozens of reactor shutdowns in Japan and reconsideration of new nuclear power plants in several countries, other countries are continuing to build new plants but not at a fast enough rate yet to make a significant further reduction in greenhouse gas emissions. Even before this accident, the prospects for major growth in nuclear power were dim. To explicate the present situation and potential future scenarios for nuclear power, this paper examines the issue of who bears the financial risk especially during the construction phase, the roles of governments in financial interventions such as loan guarantees, tax credits, and prices on greenhouse gas emissions, the effects of regulated versus market-based utility systems, the competition with relatively cheap natural gas, the roles of various governments around the world in determining the use of nuclear power, the interdependent nature of the nuclear industry with companies both competing and cooperating with each other, and the issue of whether small modular reactors or advanced nuclear reactors could result in many more plants being constructed in the United States and worldwide.

  19. Clear sky pure water - PV water pumping and desalination

    International Nuclear Information System (INIS)

    Saleh Al-Zahrani; Yaseen Al-Harbi

    2000-01-01

    Providing adequate portable drinking water is becoming a serious problem in remote areas. Saudi Arabia is a very suitable place to use renewable energy such as photovoltaic (PV) energy. For this reason, a PV system was designed and installed along with water pumping and desalination systems in the village of Sadous, about 72 km from Riyadh. The total number of panels is 158, and they give 11.06 kW. The average pumped water from the well is about 18 m 3 /day with total dissolved solids (TDS) greater than 6000 PPM. The average product water is about 5 m 3 /day with TDS less than 300 PPM. (Author)

  20. Clearing the sky : understanding SLA elements in cloud computing

    NARCIS (Netherlands)

    Comuzzi, M.; Jacobs, G.A.H.; Grefen, P.W.P.J.

    2013-01-01

    Issues characterizing cloud computing such as security, interoperability, and vendor lock-in are likely to act as inhibitors of the widespread adoption of cloud computing in organizations. These issues call for relational and contractual mechanisms to articulate the desired outcomes of service

  1. 78 FR 59401 - Self-Regulatory Organizations; ICE Clear Europe Limited; Order Approving Proposed Rule Change...

    Science.gov (United States)

    2013-09-26

    ... program designed to improve the safety and soundness of the European derivatives markets, ICE Clear Europe..., the Decomp Model provides portfolio risk coverage against at least 5-day market realizations. ICE... clearance and settlement of securities transactions and, to the extent applicable, derivative agreements...

  2. A Trading Agent for a Multi-Issue Clearing House

    Science.gov (United States)

    Debenham, John

    The potential size of the electronic business market offers great incentives to trading agents that can bargain, bid in auctions and trade in exchanges. Much of business negotiation is multi-issue. A generic 'information-based' agent is proposed for multi-issue negotiation. Successful negotiation depends on shrewd strategies driven by the right information. This agent has machinery to value information and to manage its integrity. A multi-issue, many-to-many clearing house, and an agent to trade in it, are proposed.

  3. Toward long-term all-sky time domain surveys-SINDICS: a prospective concept for a Seismic INDICes Survey of half a million red giants

    Directory of Open Access Journals (Sweden)

    Michel Eric

    2015-01-01

    Full Text Available CoRoT and Kepler have brought a new and deep experience in long-term photometric surveys and how to use them. This is true for exoplanets characterizing, stellar seismology and beyond for studying several other phenomena, like granulation or activity. Based on this experience, it has been possible to propose new generation projects, like TESS and PLATO, with more specific scientific objectives and more ambitious observational programs in terms of sky coverage and/or duration of the observations. In this context and as a prospective exercise, we explore here the possibility to set up an all-sky survey optimized for seismic indices measurement, providing masses, radii and evolution stages for half a million solar-type pulsators (subgiants and red giants, in our galactic neighborhood and allowing unprecedented stellar population studies.

  4. Promoting Dark Skies Awareness Programs Beyond the International Year of Astronomy 2009

    Science.gov (United States)

    Walker, Constance E.; Dark Skies Working Group

    2010-01-01

    The preservation of dark skies is a growing global concern, yet it is one of the easiest environmental problems people can address on local levels. For this reason, the goal of the International Year of Astronomy 2009 (IYA2009) Dark Skies Awareness Cornerstone Project is to raise public awareness of the impact of artificial lighting on local environments by getting people worldwide involved in a variety of programs. These programs provide resources on light pollution for new technologies like a presence in Second Life and podcasts, for local thematic events at national parks and observatory open houses, for international thematic events like International Dark Skies Week and Earth Hour, for a program in the arts like an international photo contest, for global citizen-science programs that measure night sky brightness worldwide, and for educational materials like a kit with a light shielding demonstration. These programs have been successfully used around the world during IYA2009 to raise awareness of the effects of light pollution on public health, economic issues, ecological consequences, energy conservation, safety and security, and astronomy. The poster will provide an update, take a look ahead at the project's sustainability, and describe how people can be involved in the future. Information about the programs is at www.darkskiesawareness.org.

  5. Sky Compass Orientation in Desert Locusts-Evidence from Field and Laboratory Studies.

    Science.gov (United States)

    Homberg, Uwe

    2015-01-01

    Locusts are long-range migratory insects. At high population density, immature animals form marching hopper bands while adults take off and form huge swarms of millions of animals. At low population densities animals are solitarious, but likewise migrate, mostly during the night. Numerous studies aimed at predicting locust infestations showed that migrations both as hopper bands and as adults are largely downwind following seasonal shifts of the tropical convergence zone taking the animals to areas of rainfall. Only a few studies provided evidence for active orientation mechanisms, including the involvement of a sun compass. This scarcity of evidence stands in contrast to recent neurobiological data showing sophisticated neuronal adaptations suited for sky compass navigation. These include a special dorsal eye region with photoreceptors suited to analyze the polarization pattern of the sky and a system of topographically arranged sky compass neurons in the central complex of the brain. Laboratory experiments, moreover, demonstrated polarotaxis in tethered flying animals. The discrepancy of these findings call for more rigorous field studies on active orientation mechanisms in locusts. It remains to be shown how locusts use their internal sky compass during mass migrations and what role it plays to guide solitarious locusts in their natural habitat.

  6. Atmospheric extinction coefficients and night sky brightness at the Xuyi Observation Station

    International Nuclear Information System (INIS)

    Zhang Hui-Hua; Liu Xiao-Wei; Zhang Hua-Wei; Xiang Mao-Sheng; Yuan Hai-Bo; Zhao Hai-Bin; Yao Jin-Sheng

    2013-01-01

    We present measurements of the optical broadband atmospheric extinction coefficients and the night sky brightness at the Xuyi Observation Station of Purple Mountain Observatory. The measurements are based on CCD imaging data taken in the Sloan Digital Sky Survey's g, r and i bands with the Xuyi 1.04/1.20 m Schmidt Telescope for the Xuyi Schmidt Telescope Photometric Survey of the Galactic Anti-center (XSTPS-GAC), the photometric part of the Digital Sky Survey of the Galactic Anti-center (DSS-GAC). The data were collected during more than 140 winter nights from 2009 to 2011. We find that the atmospheric extinction coefficients for the g, r and i bands are 0.69, 0.55 and 0.38 mag/airmass, respectively, based on observations taken on several photometric nights. The night sky brightness determined from images with good quality has median values of 21.7, 20.8 and 20.0 mag arcsec −2 and reaches 22.1, 21.2 and 20.4 mag arcsec −2 under the best observing conditions for the g, r and i bands, respectively. The relatively large extinction coefficients compared with other good astronomical observing sites are mainly due to the relatively low elevation (i.e. 180 m) and high humidity at the station.

  7. Starry sky sign: A prevalent sonographic finding in mediastinal tuberculous lymph nodes.

    Science.gov (United States)

    Alici, Ibrahim Onur; Demirci, Nilg N Yilmaz; Yilmaz, Aydin; Karakaya, Jale; Erdogan, Yurdanur

    2015-01-01

    We report a prevalent finding in tuberculous lymphadenitis (TL): Starry sky sign, hyperechoic foci without acoustic shadows over a hypoechoic background. We retrospectively searched the database for a possible relationship of starry sky sign with a specific diagnosis and also the prevalence and accuracy of the finding. Starry sky sign was found in 16 of 31 tuberculous lymph nodes, while none of other lymph nodes (1,015 lymph nodes) exhibited this finding; giving a sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of 51.6%, 100%, 100%, 98.5%, and 98.5%, respectively. Bacteriologic and histologic findings are gold standard in the diagnosis of tuberculosis, but this finding may guide the bronchoscopist in choosing the more pathologic node within a station and increase the diagnostic yield as it may relate to actively dividing mycobacteria.

  8. Stellar activity for every TESS star in the Southern sky

    Science.gov (United States)

    Howard, Ward S.; Law, Nicholas; Fors, Octavi; Corbett, Henry T.; Ratzloff, Jeff; del Ser, Daniel

    2018-01-01

    Although TESS will search for Earths around more than 200,000 nearby stars, the life-impacting superflare occurrence of these stars remains poorly characterized. We monitor long-term stellar flare occurrence for every TESS star in the accessible sky at 2-minute cadence with the CTIO-based Evryscope, a combination of twenty-four telescopes, together giving instantaneous sky coverage of 8000 square degrees. In collaboration with Owens Valley Long Wavelength Array (LWA) all-sky monitoring, Evryscope also provides optical counterparts to radio flare, CME, and exoplanet-magnetosphere stellar activity searches. A Northern Evryscope will be installed at Mount Laguna Observatory, CA in collaboration with SDSU later this year, enabling stellar activity characterization for the full TESS target list and both continuous viewing zones, as well as providing 100% overlap with LWA radio activity. Targets of interest (e.g. Proxima Cen, TRAPPIST-1) are given special focus. We are currently sensitive to stellar activity down to 1% precision at g' ~ 10 and about 0.2 of a magnitude at g' ~ 15. With 2-minute cadence and a projected 5-year timeline, with 2+ years already recorded, we present preliminary results from an activity characterization of every Southern TESS target.

  9. 78 FR 36002 - Self-Regulatory Organizations; The Options Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2013-06-14

    ... believes these results are consistent with what would be expected given the strong negative correlation... prices used by STANS to value each portfolio indicative daily quotations obtained through a third- party... options may represent a larger portion of any clearing member's portfolio in the future, and OCC has...

  10. 76 FR 19512 - Self-Regulatory Organizations; The Options Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2011-04-07

    ... Expansion of OCC's Internal Cross-Margining Program to Include the Ability of a Pair of Affiliated Clearing...-margining to create rules similar to the rules of the long-standing cross-margining program for affiliated... 42586 (August 10, 1993). OCC would not implement the internal cross-margining program for affiliated...

  11. Petyarre and Moffat: 'Looking from the Sky'

    Directory of Open Access Journals (Sweden)

    Linnell Secomb

    2013-08-01

    Full Text Available Moffatt’s Up in the Sky series draws attention to the relation between sky and earth, through the content and camera angles of the images. Similarly, Kathleen Petyarre’s Central Desert acrylic dot painting evokes this relation representing country and Dreaming from a celestial perspective—as she says ‘looking from the sky’. Yet here any association between these artists seems to end with the urban artist refusing to engage Aboriginal tradition and the desert artist focused on Dreaming, country and heritage. However, a further connection between these disparate works may also be discerned as each, in differing ways, transforms our conventional perceptions of space and time. Reading these images in relation to Walter Benjamin’s concepts of the auratic and of messianic time, I suggest that each restructures dimension and duration putting in question the (postmodern calibrations of our space/time experience. This paper stages an engagement between these artists’ works and Benjamin’s concepts exploring the variations and modifications of the spatial and the temporal that hybrid cross-cultural exchanges require and facilitate.

  12. A stochastic framework for clearing of reactive power market

    International Nuclear Information System (INIS)

    Amjady, N.; Rabiee, A.; Shayanfar, H.A.

    2010-01-01

    This paper presents a new stochastic framework for clearing of day-ahead reactive power market. The uncertainty of generating units in the form of system contingencies are considered in the reactive power market-clearing procedure by the stochastic model in two steps. The Monte-Carlo Simulation (MCS) is first used to generate random scenarios. Then, in the second step, the stochastic market-clearing procedure is implemented as a series of deterministic optimization problems (scenarios) including non-contingent scenario and different post-contingency states. In each of these deterministic optimization problems, the objective function is total payment function (TPF) of generators which refers to the payment paid to the generators for their reactive power compensation. The effectiveness of the proposed model is examined based on the IEEE 24-bus Reliability Test System (IEEE 24-bus RTS). (author)

  13. 78 FR 68496 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2013-11-14

    ... securities it issues and to support its broader debt management objective. The Floating Rate Notes will be... purposes and for forward margin and clearing fund calculations. Modification of the security database in... Notes eligible for processing.\\5\\ \\5\\ GSD issued Important Notice GOV012.13 on February 23, 2013 and...

  14. 76 FR 6648 - Self-Regulatory Organizations; The Options Clearing Corporation; Notice of Filing of Proposed...

    Science.gov (United States)

    2011-02-07

    ...-settled, European-style options. In the event of a corporate event that eliminates one of the underlying... Performance Options are highly similar to other index options cleared by OCC except for the identity and... similar corporate event. If the value of an underlying Relative Performance Index ceases to be published...

  15. The generation of hourly diffuse irradiation: A model from the analysis of the fluctuation of global irradiance series

    International Nuclear Information System (INIS)

    Posadillo, R.; Lopez Luque, R.

    2010-01-01

    An analysis of models for the estimation of hourly diffuse irradiation based on the interrelations between the hourly diffuse fraction k d and the hourly clearness index k t , has concluded that k t is not a sufficient variable for parametrizing the effect of clouds on diffuse irradiation. A detailed study of the dispersion recorded by this diffuse component for a specific clearness index under partly cloudy sky conditions has led to analyzing how the variability in the instantaneous clearness index influences this dispersion. The data sets correspond to 10 years of hourly and instantaneous value records of global and diffuse radiation collected in Cordoba, Spain. In addition to the inclusion of the sine of solar elevation as a variable into the k d -k t correlations, this model propose the inclusion of others parameters related to the variability in the normalized clearness index within an hour and with the fluctuations presented by the time series of the instantaneous values of that index. Also presented is the implementation of an algorithm permitting both the determination of the hourly diffuse irradiation and the discrimination between the different sky conditions in those situations known by the designation partly cloudy sky.

  16. Effects of multiple scattering and atmospheric aerosol on the polarization of the twilight sky

    International Nuclear Information System (INIS)

    Ugolnikov, Oleg S.; Postylyakov, Oleg V.; Maslov, Igor A.

    2004-01-01

    The paper presents a review of a number of wide-angle polarization CCD-measurements of the twilight sky in V and R color bands with effective wavelengths 550 and 700nm. The basic factors affecting (usually decreasing) the polarization of the twilight sky are the atmospheric aerosol scattering and multiple scattering. These effects were distinguished from each other, and a method of multiple-scattering separation is discussed. The results are compared with the data of numerical simulation of radiative transfer in the atmosphere for different aerosol models. The whole twilight period is divided into different stages with different mechanisms forming the twilight-sky polarization properties

  17. Flying Drosophila orient to sky polarization.

    Science.gov (United States)

    Weir, Peter T; Dickinson, Michael H

    2012-01-10

    Insects maintain a constant bearing across a wide range of spatial scales. Monarch butterflies and locusts traverse continents [1, 2], and foraging bees and ants travel hundreds of meters to return to their nests [1, 3, 4], whereas many other insects fly straight for only a few centimeters before changing direction. Despite this variation in spatial scale, the brain region thought to underlie long-distance navigation is remarkably conserved [5, 6], suggesting that the use of a celestial compass is a general and perhaps ancient capability of insects. Laboratory studies of Drosophila have identified a local search mode in which short, straight segments are interspersed with rapid turns [7, 8]. However, this flight mode is inconsistent with measured gene flow between geographically separated populations [9-11], and individual Drosophila can travel 10 km across desert terrain in a single night [9, 12, 13]-a feat that would be impossible without prolonged periods of straight flight. To directly examine orientation behavior under outdoor conditions, we built a portable flight arena in which a fly viewed the natural sky through a liquid crystal device that could experimentally rotate the polarization angle. Our findings indicate that Drosophila actively orient using the sky's natural polarization pattern. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Correction for reflected sky radiance in low-altitude coastal hyperspectral images.

    Science.gov (United States)

    Kim, Minsu; Park, Joong Yong; Kopilevich, Yuri; Tuell, Grady; Philpot, William

    2013-11-10

    Low-altitude coastal hyperspectral imagery is sensitive to reflections of sky radiance at the water surface. Even in the absence of sun glint, and for a calm water surface, the wide range of viewing angles may result in pronounced, low-frequency variations of the reflected sky radiance across the scan line depending on the solar position. The variation in reflected sky radiance can be obscured by strong high-spatial-frequency sun glint and at high altitude by path radiance. However, at low altitudes, the low-spatial-frequency sky radiance effect is frequently significant and is not removed effectively by the typical corrections for sun glint. The reflected sky radiance from the water surface observed by a low-altitude sensor can be modeled in the first approximation as the sum of multiple-scattered Rayleigh path radiance and the single-scattered direct-solar-beam radiance by the aerosol in the lower atmosphere. The path radiance from zenith to the half field of view (FOV) of a typical airborne spectroradiometer has relatively minimal variation and its reflected radiance to detector array results in a flat base. Therefore the along-track variation is mostly contributed by the forward single-scattered solar-beam radiance. The scattered solar-beam radiances arrive at the water surface with different incident angles. Thus the reflected radiance received at the detector array corresponds to a certain scattering angle, and its variation is most effectively parameterized using the downward scattering angle (DSA) of the solar beam. Computation of the DSA must account for the roll, pitch, and heading of the platform and the viewing geometry of the sensor along with the solar ephemeris. Once the DSA image is calculated, the near-infrared (NIR) radiance from selected water scan lines are compared, and a relationship between DSA and NIR radiance is derived. We then apply the relationship to the entire DSA image to create an NIR reference image. Using the NIR reference image

  19. Why Is the Sky Dark at Night?

    Science.gov (United States)

    Stinner, Arthur

    2014-01-01

    The puzzle as to just why the sky is dark at night, given that there are so many stars, has been around at least since Newton. This article summarizes six cosmological models that have been used to attempt to give an account of this puzzle including the Copernican universe, the Newton-Halley universe, the nineteenth century "one galaxy"…

  20. Responding to climate change impacts in the Sky Island Region: From planning to action

    Science.gov (United States)

    Louise W. Misztal; Gregg Garfin; Lara Hansen

    2013-01-01

    Addressing the increasing effects of climate change on natural resources requires multiple organizations, agencies, and institutions working cooperatively to incorporate climate change into resource management. In the Sky Island region of the southwestern United States and northern Mexico, Sky Island Alliance, a non-governmental organization, has convened a series of...