Effect of the total lunar eclipse of 28 July 2018 on the night sky brightness at the Observatorium Ilmu Falak Universitas Muhammadiyah Sumatera Utara

Abstract

The measurement of the Night Sky Brightness (NSB) has been done at the Observatorium Ilmu Falak Universitas Muhammadiyah Sumatera Utara (OIF UMSU) during the total lunar eclipse on 28 July 2018. NSB was measured using three Sky Quality Meters (SQMs). We were directing those SQMs to the eastern horizon, zenith, and the western horizon with a resolution of 2 seconds. The results showed that zenith direction SQM data had a change in NSB due to the lunar eclipse. Before the eclipse, the NSB was 14.78 mpsas, and the NSB during the total Moon phase was 18.03 mpsas. While the SQM data in the direction of the eastern and the western horizons are showing insignificant changes, those were 15.58 mpsas and 15.15 mpsas, respectively. These are because fog and light pollution originating from the city center of Medan are heavily influencing the area in the direction of the eastern and western horizons.