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Author |
Bará, S.; Falchi, F.; Furgoni, R.; Lima, R.C. |
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Title |
Fast Fourier-transform calculation of artificial night sky brightness maps |
Type |
Journal Article |
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Year |
2020 |
Publication |
Journal of Quantitative Spectroscopy and Radiative Transfer |
Abbreviated Journal |
Journal of Quantitative Spectroscopy and Radiative Transfer |
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Volume |
240 |
Issue |
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Pages  |
106658 |
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Keywords |
Skyglow; Light pollution; Atmospheric optics; Photometry; Radiometry; Fourier transforms |
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Abstract |
Light pollution poses a growing threat to optical astronomy, in addition to its detrimental impacts on the natural environment, the intangible heritage of humankind related to the contemplation of the starry sky and, potentially, on human health. The computation of maps showing the spatial distribution of several light pollution related functions (e.g. the anthropogenic zenithal night sky brightness, or the average brightness of the celestial hemisphere) is a key tool for light pollution monitoring and control, providing the scientific rationale for the adoption of informed decisions on public lighting and astronomical site preservation. The calculation of such maps from satellite radiance data for wide regions of the planet with sub-kilometric spatial resolution often implies a huge amount of basic pixel operations, requiring in many cases extremely large computation times. In this paper we show that, using adequate geographical projections, a wide set of light pollution map calculations can be reframed in terms of two-dimensional convolutions that can be easily evaluated using conventional fast Fourier-transform (FFT) algorithms, with typical computation times smaller than 10^-6 s per output pixel. |
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Address |
Departamento de Física Aplicada, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain; salva.bara(at)usc.es |
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Elsevier |
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English |
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English |
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0022-4073 |
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no |
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Call Number |
IDA @ john @ |
Serial |
2782 |
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Author |
Schnitt, S.; Ruhtz, T.; Fischer, J.; Hölker, F.; Kyba, C.C.M. |
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Title |
Temperature stability of the sky quality meter |
Type |
Journal Article |
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Year |
2013 |
Publication |
Sensors (Basel, Switzerland) |
Abbreviated Journal |
Sensors (Basel) |
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Volume |
13 |
Issue |
9 |
Pages |
12166-12174 |
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Keywords |
*Artifacts; Atmosphere/*analysis; Environmental Monitoring/*instrumentation; Equipment Design; Equipment Failure Analysis; Photometry/*instrumentation; Reproducibility of Results; Sensitivity and Specificity; Temperature; *Transducers; Sky Quality Meter; SQM |
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Abstract |
The stability of radiance measurements taken by the Sky Quality Meter (SQM)was tested under rapidly changing temperature conditions during exposure to a stable light field in the laboratory. The reported radiance was found to be negatively correlated with temperature, but remained within 7% of the initial reported radiance over a temperature range of -15 degrees C to 35 degrees C, and during temperature changes of -33 degrees C/h and +70 degrees C/h.This is smaller than the manufacturer's quoted unit-to-unit systematic uncertainty of 10%,indicating that the temperature compensation of the SQM is adequate under expected outdoor operating conditions. |
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Address |
Institute for Space Sciences, Freie Universitat Berlin, Carl-Heinrich-Becker-Weg 6-10, Berlin 12165, Germany. christopher.kyba@wew.fu-berlin.de |
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English |
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1424-8220 |
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PMID:24030682; PMCID:PMC3821345 |
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no |
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Call Number |
IDA @ john @ |
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194 |
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Author |
Bará, S. |
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Title |
Characterizing the zenithal night sky brightness in large territories: how many samples per square kilometre are needed? |
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Journal Article |
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Year |
2017 |
Publication |
Monthly Notices of the Royal Astronomical Society |
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Volume |
473 |
Issue |
3 |
Pages |
4164-4173 |
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Keywords |
Instrumentation; atmospheric effects; light pollution; numerical methods; photometry |
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Abstract |
A recurring question arises when trying to characterize, by means of measurements or theoretical calculations, the zenithal night sky brightness throughout a large territory: how many samples per square kilometre are needed? The optimum sampling distance should allow reconstructing, with sufficient accuracy, the continuous zenithal brightness map across the whole region, whilst at the same time avoiding unnecessary and redundant oversampling. This paper attempts to provide some tentative answers to this issue, using two complementary tools: the luminance structure function and the Nyquist–Shannon spatial sampling theorem. The analysis of several regions of the world, based on the data from the New world atlas of artificial night sky brightness, suggests that, as a rule of thumb, about one measurement per square kilometre could be sufficient for determining the zenithal night sky brightness of artificial origin at any point in a region to within ±0.1 magV arcsec–2 (in the root-mean-square sense) of its true value in the Johnson–Cousins V band. The exact reconstruction of the zenithal night sky brightness maps from samples taken at the Nyquist rate seems to be considerably more demanding. |
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Address |
1Departamento de Física Aplicada, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Galicia, Spain; salva.bara(at)usc.es |
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Oxford Academic |
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English |
Summary Language |
English |
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ISSN |
0035-8711 |
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no |
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Call Number |
IDA @ john @ |
Serial |
2164 |
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Author |
Jechow, A.; Holker, F.; Kyba, C.C.M. |
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Title |
Using all-sky differential photometry to investigate how nocturnal clouds darken the night sky in rural areas |
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Journal Article |
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Year |
2019 |
Publication |
Scientific Reports |
Abbreviated Journal |
Sci Rep |
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Volume |
9 |
Issue |
1 |
Pages |
1391 |
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Keywords |
Skyglow; differential photometry; clouds; sky brightness |
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Abstract |
Artificial light at night has affected most of the natural nocturnal landscapes worldwide and the subsequent light pollution has diverse effects on flora, fauna and human well-being. To evaluate the environmental impacts of light pollution, it is crucial to understand both the natural and artificial components of light at night under all weather conditions. The night sky brightness for clear skies is relatively well understood and a reference point for a lower limit is defined. However, no such reference point exists for cloudy skies. While some studies have examined the brightening of the night sky by clouds in urban areas, the published data on the (natural) darkening by clouds is very sparse. Knowledge of reference points for the illumination of natural nocturnal environments however, is essential for experimental design and ecological modeling to assess the impacts of light pollution. Here we use differential all-sky photometry with a commercial digital camera to investigate how clouds darken sky brightness at two rural sites. The spatially resolved data enables us to identify and study the nearly unpolluted parts of the sky and to set an upper limit on ground illumination for overcast nights at sites without light pollution. |
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Address |
GFZ German Research Centre for Geosciences, Remote Sensing, Telegrafenberg, 14473, Potsdam, Germany |
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English |
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Edition |
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ISSN |
2045-2322 |
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Notes |
PMID:30718668; PMCID:PMC6361923 |
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no |
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Call Number |
IDA @ john @ |
Serial |
2188 |
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Author |
David, A.; Smet, K.A.G.; Whitehead, L. |
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Title |
Methods for Assessing Quantity and Quality of Illumination |
Type |
Journal Article |
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Year |
2019 |
Publication |
Annual Review of Vision Science |
Abbreviated Journal |
Annu Rev Vis Sci |
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Volume |
5 |
Issue |
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Pages |
479-502 |
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Keywords |
Vision; Review; Photometry; Colorimetry |
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Abstract |
Human vision provides useful information about the shape and color of the objects around us. It works well in many, but not all, lighting conditions. Since the advent of human-made light sources, it has been important to understand how illumination affects vision quality, but this has been surprisingly difficult. The widespread introduction of solid-state light emitters has increased the urgency of this problem. Experts still debate how lighting can best enable high-quality vision-a key issue since about one-fifth of global electrical power production is used to make light. Photometry, the measurement of the visual quantity of light, is well established, yet significant uncertainties remain. Colorimetry, the measurement of color, has achieved good reproducibility, but researchers still struggle to understand how illumination can best enable high-quality color vision. Fortunately, in recent years, considerable progress has been made. Here, we summarize the current understanding and discuss key areas for future study. |
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Address |
Department of Physics and Astronomy, University of British Columbia, Vancouver BC V6T 1Z1, Canada; email: lorne.whitehead@ubc.ca |
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English |
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2374-4642 |
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Notes |
PMID:31226013 |
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Call Number |
GFZ @ kyba @ |
Serial |
2576 |
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