云南天文台丽江高美古和昆明的大气视宁度研究

研究云南天文台昆明凤凰山和丽江高美古两地点的大气视宁度。利用云南天文台于1994年建立的3孔较差视宁度监视仪（3孔DIMM），对这两个地点的视宁度对比观测。还利用云南天文台的1米望远镜所得到的视宁度与3孔DIMM所测的视宁度进行对比。1米望远镜和3孔DIMM同时观测了7个晚上，各取得308组数据，它们的视宁度平均分别为0．90〃和0．84〃。还讨论了3孔DIMM采用不同曝光时间对视宁度测量值的影响，从实验得出3孔DIMM采用20ms曝光比采用8ms曝光所测视宁度的值要好15％左右。从1995年5月－1996年12月，对丽江高美古和昆明凤凰山二地进行了视宁度的对比观测。在高美古和昆明分别观测了234夜和256夜，观测结果是两个点的视宁度平均；丽江为0．70〃，昆明为0．95〃，同时也统计了两个点的月平均视宁度和最好夜的视宁度，并讨论了两地视宁度随时间的变化规律。

A STUDY OF THEASTRONOMICAL SEEINGS AT TWO SITES OF KUNMING AND LIJIANG

The seeings of two sites at Yunnan Observatory of Kunming and Gaomeigu Station of Lijiang are studied by using the three sub-aperture DIMM of Yunnan Observatory. The FWHMs given by 1 m telescope and the seeing measured by DIMMs are compared. In terms of the simultaneous data of seven days' observations, the average FWHMs of 1 m telescope is 1.17", while the average seeing of DIMM is 0.84". The authors tested the effect of time exposure on the measured seeing of three sub-aperture DIMM and found that the seeing of 20 ms time exposure is 15 % better than that of 8 ms time exposure. 　　From May 1995 to December 1996 the authors compared observations of two sites and obtained the data of 234 nights in Gaomeigu and of 256 nights in Yunnan observatory. The average seeings of two sites are, respectively, 0. 70" at Gaomeigu and 0.95" at Yunnan Observatory. The seeing variations with time of the two sites are also studied.