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Site-testing at the Muztagh-ata Site V. Nighttime Cloud Amount during the Last Five Years

2023; IOP Publishing; Volume: 23; Issue: 4 Linguagem: Inglês

10.1088/1674-4527/acc29b

2397-6209

Jing Xu, Guojie Feng, Guang-Xin Pu, Letian Wang, Zihuang Cao, Liqing Ren, Xuan Zhang, Shuguo Ma, Chunhai Bai, Ali Esamdin, Jian Lì, Yuan Tian, Zheng Wang, Yongheng Zhao, Jianrong Shi,

Astronomical Observations and Instrumentation

The clarity of nights is the major factor that should be carefully considered for optical/infrared astronomical observatories in site-testing campaigns. Cloud coverage is directly related to the amount of time available for scientific observations at observatories. In this article, we report on the results of detailed night-time cloud statistics and continuous observing me derived from ground-based all-sky cameras at the Muztagh-ata site from 2017 to 2021. Results obtained from acquisition data show that the proportion of the annual observing me at the Muztagh-ata site is 65%, and the best period with the least cloud coverage and longer continuous observing time is from September to February. We made a comparison of the monthly mean observing nights obtained from our all-sky cameras and CLARA dataset, results show that the discrepancy between them may depend on the cloud top heights. On average, this site can provide 175 clear nights and 169 nights with at least 4 hours of continuous observing time per year.