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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 |
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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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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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1424-8220 |
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PMID:24030682; PMCID:PMC3821345 |
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IDA @ john @ |
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194 |
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Author |
Bará, S. |
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Title |
Variations on a classical theme: On the formal relationship between magnitudes per square arcsecond and luminance |
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Journal Article |
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Year |
2017 |
Publication |
International Journal of Sustainable Lighting |
Abbreviated Journal |
Intl J of Sustainable Lighting |
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Volume |
19 |
Issue |
2 |
Pages |
77 |
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Keywords |
Instrumentation; skyglow; luminance; magnitude; sky brigthness; photometry |
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Abstract |
The formal link between magnitudes per square arcsecond and luminance is discussed in this paper. Directly related to the human visual system, luminance is defined in terms of the spectral radiance of the source, weighted by the CIE V(l) luminous efficiency function, and scaled by the 683 lm/W luminous efficacy constant. In consequence, any exact and spectrum-independent relationship between luminance and magnitudes per square arcsecond requires that the last ones be measured precisely in the CIE V(l) band. The luminance value corresponding to mVC=0 (zero-point of the CIE V(l) magnitude scale) depends on the reference source chosen for the definition of the magnitude system. Using absolute AB magnitudes, the zero point luminance of the CIE V(l) photometric band is 10.96 x 104 cd·m-2. |
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Departamento de Física Aplicada, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain; salva.bara(at)usc.es |
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English |
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English |
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2586-1247 |
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IDA @ john @ |
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2162 |
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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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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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GFZ German Research Centre for Geosciences, Remote Sensing, Telegrafenberg, 14473, Potsdam, Germany |
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2045-2322 |
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PMID:30718668; PMCID:PMC6361923 |
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no |
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Call Number |
IDA @ john @ |
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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 |
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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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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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Department of Physics and Astronomy, University of British Columbia, Vancouver BC V6T 1Z1, Canada; email: lorne.whitehead@ubc.ca |
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2374-4642 |
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Notes |
PMID:31226013 |
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no |
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Call Number |
GFZ @ kyba @ |
Serial |
2576 |
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Author |
Bará, S.; Escofet, J. |
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Title |
On lamps, walls, and eyes: The spectral radiance field and the evaluation of light pollution indoors |
Type |
Journal Article |
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Year |
2018 |
Publication |
Journal of Quantitative Spectroscopy and Radiative Transfer |
Abbreviated Journal |
J of Quant Spect and Rad Trans |
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Volume |
205 |
Issue |
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Pages |
267-277 |
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Keywords |
Instrumentation; Light pollution; Artificial light at night; Light field; Radiance field; Radiometry; Photometry |
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Abstract |
Light plays a key role in the regulation of different physiological processes, through several visual and non-visual retinal phototransduction channels whose basic features are being unveiled by recent research. The growing body of evidence on the significance of these effects has sparked a renewed interest in the determination of the light field at the entrance pupil of the eye in indoor spaces. Since photic interactions are strongly wavelength-dependent, a significant effort is being devoted to assess the relative merits of the spectra of the different types of light sources available for use at home and in the workplace. The spectral content of the light reaching the observer eyes in indoor spaces, however, does not depend exclusively on the sources: it is partially modulated by the spectral reflectance of the walls and surrounding surfaces, through the multiple reflections of the light beams along all possible paths from the source to the observer. This modulation can modify significantly the non-visual photic inputs that would be produced by the lamps alone, and opens the way for controlling—to a certain extent—the subject's exposure to different regions of the optical spectrum. In this work we evaluate the expected magnitude of this effect and we show that, for factorizable sources, the spectral modulation can be conveniently described in terms of a set of effective filter-like functions that provide useful insights for lighting design and light pollution assessment. The radiance field also provides a suitable bridge between indoor and outdoor light pollution studies. |
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Address |
Área de Óptica, Departamento de Física Aplicada, Universidade de Santiago de Compostela, 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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IDA @ john @ |
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2163 |
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