The durations of good imaging within a fixed year are preliminarily obtained by statistical analysis of imaging quality obtained from spectral observations in 1982 with the horizontal spectrograph installed at the yunnan observatory . the results show that in the autumn , september and august , a good image is usually available . for a daytime , there are two time intervals during which the solar image is relatively better than other time , one is in the morning 2 3 hours after the sunrise ; another in the afternoon 3 4 hours before the sunset , and it lasts about 0 . 5 1 . 0 hours for each 通過對云臺水平式太陽光譜儀1982年太陽光譜觀測中的成像質(zhì)量情況統(tǒng)計分析,初步得到光譜儀一年中成像質(zhì)量優(yōu)良的時間在秋夏9月和8月份;一天內(nèi)有兩次像質(zhì)優(yōu)良的時間,上、下午各有一次,分別在日出后2 3小時和日落前3 4小時各有半小時到1小時左右的時間。