Summary
This paper establishes conversion factors between night sky brightness measured in astronomical magnitudes and visual luminance in SI units (cd/m²), showing that these conversions depend significantly on the spectral composition of skyglow. The scotopic-to-photopic luminance ratio varies widely (0.8–2.5) depending on light source spectrum, which has implications for understanding how different light sources affect dark-adapted vision.
Key Findings
- Photopic luminance for mV=22.0 mpsas (typical dark sky) ranges from 176–213 μcd/m² (AB scale) or 187–227 μcd/m² (Vega scale), depending on skyglow spectrum.
- Photopic zero-point luminances for mV=0.00 mpsas range from 1.11–1.34 × 10⁵ cd/m² (AB) and 1.18–1.43 × 10⁵ cd/m² (Vega), varying with spectral power distribution.
- Scotopic-to-photopic (S/P) luminance ratio varies from 0.8 to 2.5 across measured skyglow spectra, reflecting the strong influence of light source CCT and spectrum on mesopic/scotopic visual response.
- Zero-point luminances decrease with increasing correlated colour temperature (CCT) under photopic adaptation, but this relationship reverses under scotopic adaptation.
Categories
The Science of Light: Analyzes photometric transformations between magnitude scales and luminance (cd/m²) for different spectral power distributions, directly relevant to lighting measurement standards and photopic/scotopic adaptation.
Author(s)
S Bará, M Aubé, J Barentine
Publication Year
2020
Number of Citations
23
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