Abstract
Photoelectric measurements of the night sky brightness and the light pollution of Kottamia Observatory have been carried out and the deduced results are expressed in mag/sec2. The maximum brightness of the sky in the direction of Cairo city at zenith distance 45° and azimuth 70° when the sun is almost 60° below the horizon are 22.68; 21.54 and 19.82 mag/sec2 for blue, yellow and red colours respectively. The corresponding values of night sky background are 22.94; 21.85 and 20.14 mag/sec2 respectively.
The isophotes of the sky brightness at Kottamia Observatory have been drawn for blue, yellow and red colours. The variations of the night sky brightness and the (B-V) colour index with altitude of the observed point have been studied.
The light pollution and the night sky brightness at the site of Kottamia Observatory is compared with that deduced by different investigators at other sites. It has been shown that the sky brightness at zenith distance 45° at Kottamia Observatory site is similar to Kitt Peak and Palomar Observatory sites. Kottamia Observatory site is slightly brighter than Junipero Serra while it is darker than Mount Hamilton and San Jose sites. The comparative results have been carried out at blue and yellow colours. No comparison is obtained at red as there is no data published for the red colour.
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Nawar, S., Morcos, A.B. & Mikhail, J.S. Light pollution and night sky brightness at the site of Kottamia Observatory. Earth Moon Planet 70, 133–141 (1995). https://doi.org/10.1007/BF00619457
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DOI: https://doi.org/10.1007/BF00619457