Zenithal Sky Brightness Measurement at Selangor Observatory

The first continuous assessment of night sky brightness (NSB) at Selangor Observatory are presented. The brightness at night sky was monitored over 6 months in 2018, using portable light sensor called the Sky Quality Meter-type USB-Data Logging with a fixed position - pointing towards zenith. From the 179 records of night, the study shows that the average NSB readings at Selangor Observatory is 20.04 ± 0.18 magnitude per square arc second (MPSAS), after excluding the moonlight factor. Meanwhile, during the stable night sky conditions, the most recorded NSB value is 21.1 MPSAS with 0.78 MPSAS range and 21.03 MPSAS in average. Therefore, Selangor Observatory is still a relevant location for the implementation of astronomical work since it has a night sky within Bortle scale Class 4 to 5.