New analysis of the fraction of observable nights at astronomical sites based on FengYun-2 satellite data

TL;DR

This paper introduces a satellite-based method to estimate the fraction of observable nights at astronomical sites, validated across multiple locations, revealing regional differences in night observability.

Contribution

The paper presents a novel approach using FengYun-2 satellite data to accurately estimate observable nights, improving site selection for astronomy.

Findings

Good agreement with previous estimates of observable nights.

Higher fraction of observable nights near 40°N in China.

Method validated at 29 astronomical sites.

Abstract

The fraction of observable nights is an essential parameter for selecting astronomical sites. In recent years, meteorological satellite data have played an essential role in recognising and providing statistics of observable nights. We present a method to estimate the fraction of observable nights based on the FengYun-2 series of geostationary meteorological satellites and weather records of multiple astronomical sites. We have calculated the fraction of observable nights at 27 sites in Indonesia and two astronomical sites in China to validate the method. The results derived from our method show good agreement with previous works. Furthermore, we have derived the yearly distribution of the fraction of observable nights above China, which indicates the area near 40$^{\circ}$N has more observable nights than other areas in China.