Short-Term Variability of Extinction by Broadband Stellar Photometry.

Musat, I. C. ; Ellingson, R. G.

Technical Information Center Oak Ridge Tennessee

关键词: Sky;    Photometry;    Stars;    Aerosols;    Calibration;   

RP-ID  :  DE2005841538

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

Aerosol optical depth variation over short-term time intervals is determined from broadband observations of stars with a whole sky imager. The main difficulty in such measurements consists of accurately separating the star flux value from the non-stellar diffuse skylight. Using correction method to overcome this difficulty, the monochromatic extinction at the ground due to aerosols is extracted from heterochromatic measurements. A form of closure is achieved by comparison with simultaneous or temporally close measurements with other instruments, and the total error of the method, as a combination of random error of measurements and systematic error of calibration and model, is assessed as being between 2.6 and 3% rms.