Discussion on the Optimal Duration of Solar Spectral Observation at the Phoenix Mountain of Yunnan Observatory

We take the duration as the optimal period during which the more and better observational data are available within one year. After statistical analyzing the related spectral data obtained with the spectrograph from 1976 to 1987, an annual distribution of optimal duration of solar spectral observation at the Phoenix Mountain of Yunnan Observatory is preliminary obtained, the result shows that the optimal durations in a year are September, then, from March to April.