摘要
Cloud cover plays a pivotal role in assessing observational conditions for astronomical site-testing.Except for the fraction of observing time,its fragmentation also wields a significant influence on the quality of nighttime sky clarity.In this article,we introduce the functionΓ∈[0,1],designed to comprehensively capture both the fraction of available observing time and its continuity.Leveraging in situ measurement data gathered at the Muztagh-Ata site between 2017 and 2021,we showcase the effectiveness of our approach.The statistical result illustrates that the Muztagh-Ata site affords approximately 122 nights that were absolutely clear and 205 very good nights annually,corresponding toΓ≥0.9 andΓ≥0.36 respectively.
基金
supported by the Chinese Academy of Science(CAS)“Light of West China”Program(No.2022_XBQNXZ_014)
the Joint Research Fund in Astronomy under a cooperative agreement between the National Natural Science Foundation of China(NSFC),the Chinese Academy of Sciences(CAS)(grant No.U2031209)
the Xinjiang Natural Science Foundation(grant No.2022D01A357)
the National Natural Science Foundation of China(NSFC,grant No.11873081)。
