A study of atmospheric seeing at two sites in Kunming and Lijiang

The seeing at Yunnan Observatory, Kunming and at its subsidiary observing station at Gaomeigu near Lijiang is investigated using the three subaperture DIMM of Yunnan Observatory. The FWHMs given by the 1m telescope and the seeing measured by DIMMs are compared. In terms of simultaneous observations in 7 days, the average FWHMs of the 1m telescope is 1.17", while the average seeing of the DIMM is 0.84". The authors tested the effect of time exposure on the measured seeing of the three sub-aperture DIMM and found that the seeing with 20 ms time exposure is 15% better than that of the 8 ms. The authors made comparison observations from May 1995 to December 1996 at the two sites and obtained data on 234 nights at Gaomeigu and on 256 nights at Kunming. The average seeing is 70" at Gaomeigu and 0.95" at Kunming. The variation of seeing with time at the two sites is also studied.