The Measurement of Instrument Efficiency for the BATC Photometric System

Four Oke-Gunn(OG) standards, HD19445, HD84937, BD+17°4708 and BD+26°2606 are used as standard stars for flux calibration in the BATC project. We use the BATC 14-color filters among the BATC 15 intermediate-band filters (except b band) for photometry of the sky regions of the two standard stars: HD19445 and HD84937. We also use two automatic data reduction programs Pipeline I and Pipeline ??? to process observational data and calibrate the BATC magnitudes of the other stars in the observed sky regions with the known BATC standard star. In this paper, we have evaluated the sky brightness, found the relationship among the signal-to-noise ratio, the BATC magnitudes and the exposure time, and got the experiential formula among the three quantities.