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Author Bará, S.; Aubé, M.; Barentine, J.; Zamorano, J.
Title Magnitude to luminance conversions and visual brightness of the night sky Type Journal Article
Year 2020 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal MNRAS
Volume 493 Issue 2 Pages 2429–2437
Keywords Skyglow; light pollution; atmospheric effects; techniques: photometric; methods: numerical; luminance
Abstract The visual brightness of the night sky is not a single-valued function of its brightness in other photometric bands, because the transformations between photometric systems depend on the spectral power distribution of the skyglow. We analyze the transformation between the night sky brightness in the Johnson-Cousins V band (mV, measured in magnitudes per square arcsecond, mpsas) and its visual luminance (L, in SI units cd m−2) for observers with photopic and scotopic adaptation, in terms of the spectral power distribution of the incident light. We calculate the zero-point luminances for a set of skyglow spectra recorded at different places in the world, including strongly light-polluted locations and sites with nearly pristine natural dark skies. The photopic skyglow luminance corresponding to mV = 0.00 mpsas is found to vary between 1.11–1.34 × 105 cd m−2 if mV is reported in the absolute (AB) magnitude scale, and between 1.18–1.43 × 105 cd m−2 if a Vega scale for mV is used instead. The photopic luminance for mV = 22.0 mpsas is correspondingly comprised between 176 and 213 μcd m−2 (AB), or 187 and 227 μcd m−2 (Vega). These constants tend to decrease for increasing correlated color temperatures (CCT). The photopic zero-point luminances are generally higher than the ones expected for blackbody radiation of comparable CCT. The scotopic-to-photopic luminance ratio (S/P) for our spectral dataset varies from 0.8 to 2.5. Under scotopic adaptation the dependence of the zero-point luminances with the CCT, and their values relative to blackbody radiation, are reversed with respect to photopic ones.
Address Departamento de Física Aplicada, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia; salva.bara(at)usc.gal
Corporate Author Thesis
Publisher Oxford Academic Place of Publication Editor
Language English Summary Language English Original Title
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Notes Approved no
Call Number IDA @ john @ Serial 2825
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Author Linares, H.; Masana, E.; Ribas, S.J.; Aubé, M.; Simoneau, A.; Bará, S.
Title Night sky brightness simulation over Montsec protected area Type Journal Article
Year 2020 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer
Volume 249 Issue Pages 106990
Keywords Skyglow
Abstract Night sky brightness over Montsec Observatory (north-east of Spain) has been computed and checked against measurements using Illumina numerical model [2]. In a previous publication [20] the methodology was validated and light pollution received in the observatory coming from a unique city was computed. Here we present a simulation that includes all the sources that has a significant impact over the quality of the night sky in this area. The decision of which sources should be included in the simulations was taken following the methodology explained by [6]: using a point spread function (PSF) as a simple approach to estimate which sources are brightening the sky dome over the observer. An ad hoc PSF derived with Illumina was used with the purpose of avoiding to have to rely on already existing empirical PSF. The resulting PSF can be used in any location with similar atmospheric conditions. Differences in the spectrum of the lamps can be accounted easily by adjusting a spectrum scale factor. Illumina simulates the artificial sky brightness received (W/sr/m2) by an observer from any direction. Adding the natural sky brightness allows to compare the simulations to measurements taken with different instrumentation. In our case simulations were checked against ASTMON, SQC and SQM measurements. They show a good agreement both in absolute values and in geographical patterns for the three filters studied, B, V and R. The methodology presented opens many possibilities, such as increasing the reliability of the maps that point out the light pollution main contributors for any location, and reducing the amount of time needed to perform an accurate simulation of the night sky brightness.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4073 ISBN (up) Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 2923
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Author Ribas, S. J.; Aubé, M.; Bará, S.; Bouroussis, C.; Canal-Domingo, R.; Espey, B.; Hänel, A.; Jechow, A.; Kolláth, Z.; Marti, G.; Massana, P.; Schmidt, W.; Spoelstra, H.; Wuchterl, G.; Zamorano, J.; Kyba, C.
Title Report of the 2016 STARS4ALL/LoNNe Intercomparison Campaign Type Report
Year 2017 Publication Abbreviated Journal
Volume Issue Pages
Keywords Skyglow; Instrumentation
Abstract The 2016 LoNNe (Loss of the Night Network) intercomparison campaign is the fourth of four campaigns planned during EU COST Action ES1204. The first campaign took place in 2013 in Lastovo, Croatia, the second in Madrid, Spain (Bará et al 2015), the third in Torniella and Florence, Italy (Kyba et al 2015a). The 2016 campaign took place at the Parc Astronòmic Montsec (PAM). The campaign continued the strategy of taking measurements at multiple sites, this year with a main fixed site and then excursions to other sites. The goals of the campaigns included:

● Understanding the difference between extinction measurements made by DSLR photometry and classical astronomical (telescope) photometry, and also understanding the relation between extinction and sky brightness at these two sites.

● Examining the difference in radiance measured with the mosaic technique of the US National Parks Service camera compared to all-sky fisheye imagery

● Examining the relationships between all-sky and zenith radiance reported by different instruments

● Quantifying the sky brightnes at the sites, including full zenith spectral radiance at selected locations

● Measuring the systematic uncertainty on handheld SQM observations due to unit-to-unit differences
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Corporate Author Thesis
Publisher GFZ Data Services Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN (up) Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 3057
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