Light pollution near the astronomical observatories
Authors:
M. Kocifaj
Image & caption:
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Image caption::
The convergence rate for calculated diffuse irradiance ratio at a measuring point that is surrounded by Garstang-like (top panel) and cosine-like (bottom panel) light sources. The left-hand y-axis is for black curves, while the right-hand y-axis is for grey curves. The spectrum of the ground-based light source (NAV-4Y) is integrated over a 10-nm bandwidth centred on nominal wavelength 658 nm.
Description:
A growth of light pollution is continuously identified, especially in densely populated regions in the United States or Europe. As a consequence the observational conditions may dramatically degrade even if there is no one important light source near the astronomical observatory. This is because of quasi-uniform distribution of light sources across the large territory. We have analyzed the effect of two most typical light sources with distinct radiative patterns - Garstang‘s-like source with preferred emission to low elevation angles, and cosine-like source with directionally independent luminance. It has been shown that cosine-like sources contribute to the light pollution effects negligibly if their distances are not below 10 km. Contrary, the Garstang’s-like sources may be important even if situated more than 40 km from the measuring point. In addition, the sky radiances in nominal spectral lines of UBV (or UBVRI) system can markedly vary with microphysical characteristics of airborne aerosol particles.
SK
SAS
