On Sky Brightness Variantion Caused by Annular Solar Eclipse Observed with CCD Cameras

Annular solar eclipse took place at Jan 15, 2010, and Qingdao was one of best good places to observe it. In this paper, the authors used two CCD cameras to take photos of zenith sky on Dongmen Mt. of Qingdao at Jan 15, 2010, and Jan 16, 2010, to study the effect of annular solar eclipse on the sky brightness at the dusk. The principle component analysis method was used to analyze the variations of sky brightness caused by the annular eclipse comparing with the normal condition at Jan 16, 2010. The annular solar eclipse affected seriously the normal variations of red, green and blue components, among which components of red and green were more affected than that of blue. Meantime, the red component was most sensitive to the annular solar eclipse. The annular solar eclipse affected the mean gray each epoch with a certain time lag by comparing gray curves in Jan 15, 2010, and Jan 16, 2010.