Atmospheric extinction coefficients and night sky brightness at Bosscha Observatory

Abstract

We conducted a continuous sky brightness monitoring project in 2023 using the 14-inch (f/7.2) Bosscha Robotic Telescope (BRT) with Bessel filters at Bosscha Observatory. We present the initial measurement result of the extinction coefficient and sky brightness of three photometric nights from July to September 2023 using absolute photometry methods on photometric standard stars. The measurement results indicate the values of the first-order extinction coefficients span from k b ′ = 0.1344 to 0.1596, k v ′ = 0.0931 to 0.1901, k r ′ = 0.1208 to 0.1592, and k i ′ = 0.0836 to 0.0967 with a typical error of 0.001 for two similar night. On September 12, our measurement results were k b ′ = 0.6186 ± 0.0081, k v ′ = 0.5404 ± 0.0104, k r ′ = 0.3684 ± 0.0122, k i ′ = 0.2483 ± 0.0191. Applying these values to the sky field reveals the average brightness in the V-band-pass, respectively 18.807 ± 0.061, 18.999 ± 0.052, and 18.867 ± 0.039, with a color index B − V of 0.421 ± 0.111, 0.236 ± 0.094 and 0.426 ± 0.064. The results are consistent with measurements from the transformed Sky Quality Meter (SQM) corresponding to the suitable filters.