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Author  |
Bará, S.; Rodríguez-Arós, Á.; Pérez, M.; Tosar, B.; Lima, R.; Sánchez de Miguel, A.; Zamorano, J. |
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Title |
Estimating the relative contribution of streetlights, vehicles, and residential lighting to the urban night sky brightness |
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Journal Article |
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Year |
2018 |
Publication |
Lighting Research & Technology |
Abbreviated Journal |
Lighting Res & Tech |
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Issue |
October 2018 |
Pages |
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Keywords |
Remote Sensing; traffic; Roadway lighting |
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Abstract |
Under stable atmospheric conditions the brightness of the urban sky varies throughout the night following the time course of the anthropogenic emissions of light. Different types of artificial light sources (e.g. streetlights, residential, and vehicle lights) have specific time signatures, and this feature makes it possible to estimate the amount of brightness contributed by each of them. Our approach is based on transforming the time representation of the zenithal night sky brightness into a modal expansion in terms of the time signatures of the different sources of light. The modal coefficients, and hence the absolute and relative contributions of each type of source, can be estimated by means of a linear least squares fit. A practical method for determining the time signatures of different contributing sources is also described, based on wide-field time-lapse photometry of the urban nightscape. Our preliminary results suggest that, besides the dominant streetlight contribution, artificial light leaking out of the windows of residential buildings may account for a significant share of the time-varying part of the zenithal night sky brightness at the measurement locations, whilst the contribution of the vehicle lights seems to be significantly smaller. |
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Address |
Área de Óptica, Dept. Física Aplicada, Facultade de Óptica e Optometría, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Galicia, Spain. salva.bara(at)usc.es |
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SAGE |
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English |
Summary Language |
English |
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ISSN |
1477-1535 |
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Call Number |
GFZ @ kyba @ |
Serial |
2052 |
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Author |
Bará, S.; Tapia, C.; Zamorano, J. |
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Title |
Absolute Radiometric Calibration of TESS-W and SQM Night Sky Brightness Sensors |
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Journal Article |
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Year |
2019 |
Publication |
Sensors |
Abbreviated Journal |
Sensors |
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Volume |
19 |
Issue |
6 |
Pages |
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Keywords |
Instrumentation; calibration; SQM; TESS; photometer; sky brightness |
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Abstract |
We develop a general optical model and describe the absolute radiometric calibration of the readings provided by two widely-used night sky brightness sensors based on irradiance-to-frequency conversion. The calibration involves the precise determination of the overall spectral sensitivity of the devices and also the constant G relating the output frequency of the light-to-frequency converter chip to the actual band-weighted and field-of-view averaged spectral radiance incident on the detector (brightness). From these parameters, we show how to define a rigorous astronomical absolute photometric system in which the sensor measurements can be reported in units of magnitudes per square arcsecond with precise physical meaning. |
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Address |
Departmento Física Aplicada, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain; salva.bara(at)usc.es |
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MDPI |
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English |
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English |
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1424-8220 |
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Call Number |
IDA @ john @ |
Serial |
2263 |
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Author |
Bará, S.; Tilve, V.; Nievas, M.; Sanchez de Miguel, A.; Zamorano, J. |
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Title |
Zernike power spectra of clear and cloudy light-polluted urban night skies |
Type |
Journal Article |
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Year |
2015 |
Publication |
Applied Optics |
Abbreviated Journal |
Appl. Opt. |
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Volume |
54 |
Issue |
13 |
Pages |
4120-4129 |
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Keywords |
Skyglow; artificial ligh at night; light pollution; Zernike; power spectrum; atmospheric optics; imaging systems; image analysis |
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Abstract |
The Zernike power spectra of the all-sky night brightness distributions of clear and cloudy nights are computed using a modal projection approach. The results obtained in the B, V and R Johnson-Cousins' photometric bands during a one-year campaign of observations at a light-polluted urban site show that these spectra can be described by simple power laws with exponents close to -3 for clear nights and -2 for cloudy ones. The second-moment matrices of the Zernike coefficients show relevant correlations between modes. The multiplicative role of the cloud cover, that contributes to a significant increase of the brightness of the urban night sky in comparison with the values obtained in clear nights, is described in the Zernike space. |
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Address |
Area de Optica, Dept. Fisica Aplicada. Facultade de Fisica / Facultade de Optica e OptometrÃa Universidade de Santiago de Compostela Campus Sur, E-15782 Santiago de Compostela, Galicia, Spain; salva.bara@usc.es |
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Optical Society of America |
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English |
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English |
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Call Number |
IDA @ john @ |
Serial |
1156 |
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Author |
Barducci, A.; Marcoionni, P.; Pippi, I.; Poggesi, M. |
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Title |
Effects of light pollution revealed during a nocturnal aerial survey by two hyperspectral imagers |
Type |
Journal Article |
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Year |
2003 |
Publication |
Applied Optics |
Abbreviated Journal |
Appl. Opt. |
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Volume |
42 |
Issue |
21 |
Pages |
4349 |
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Keywords |
Remote Sensing |
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Abstract |
A remote-sensing campaign was performed in September 2001 at nighttime under clear-sky conditions before moonrise to assess the level of light pollution of urban and industrial origin. Two hyperspectral sensors, namely, the Multispectral Infrared and Visible Imaging Spectrometer and the Visible Infrared Scanner-200, which provide spectral coverage from the visible to the thermal infrared, were flown over the Tuscany coast (Italy) on board a Casa 212 airplane. The acquired images were processed to produce radiometrically calibrated data, which were then analyzed and compared with ground-based spectral measurements. Calibrated data acquired at high spectral resolution (∼2.5 nm) showed a maximum scene brightness almost of the same order of magnitude as that observed during similar daytime measurements, whereas their average luminosity was 3 orders of magnitude lower. The measurement analysis confirmed that artificial illumination hinders astronomical observations and produces noticeable effects even at great distances from the sources of the illumination. |
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0003-6935 |
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Call Number |
GFZ @ kyba @ |
Serial |
2438 |
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Author |
Barentine, J.C. |
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Title |
Methods for Assessment and Monitoring of Light Pollution around Ecologically Sensitive Sites |
Type |
Journal Article |
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Year |
2019 |
Publication |
Journal of Imaging |
Abbreviated Journal |
J. Imaging |
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Volume |
5 |
Issue |
5 |
Pages |
54 |
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Keywords |
Instrumentation; Skyglow; Remote Sensing; Review |
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Abstract |
Since the introduction of electric lighting over a century ago, and particularly in the decades following the Second World War, indications of artificial light on the nighttime Earth as seen from Earth orbit have increased at a rate exceeding that of world population growth during the same period. Modification of the natural photic environment at night is a clear and imminent consequence of the proliferation of anthropogenic light at night into outdoor spaces, and with this unprecedented change comes a host of known and suspected ecological consequences. In the past two decades, the conservation community has gradually come to view light pollution as a threat requiring the development of best management practices. Establishing those practices demands a means of quantifying the problem, identifying polluting sources, and monitoring the evolution of their impacts through time. The proliferation of solid-state lighting and the changes to source spectral power distribution it has brought relative to legacy lighting technologies add the complication of color to the overall situation. In this paper, I describe the challenge of quantifying light pollution threats to ecologically-sensitive sites in the context of efforts to conserve natural nighttime darkness, assess the current state of the art in detection and imaging technology as applied to this realm, review some recent innovations, and consider future prospects for imaging approaches to provide substantial support for darkness conservation initiatives around the world. |
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2313-433X |
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GFZ @ kyba @ |
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2498 |
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