Atmospheric Transparency And Sky Background Brightness at Yunnan Observatory And The Reduction Coefficients of Photometric System to 35cm Telescope

The extinction coefficients in the UBV wave bands, the reduction coefficients of the photometric system to the 35 cm telescope and the sky background brightness at Yunnan Observatory have been determined by means of electro-photometer during Jan.-Dec. 1983, and the results are introducted in this paper.