Flux calibration of the BATC survey and its application for checking the consistency of the Oke-Gunn standards

Four Oke-Gunn (OG) standards, HD 19445, HD 84937, BD+26 2606 and BD+17 4708 are used as standard stars for flux calibration in the BATC project. They are also widely used in the visual wavelength region in many other photomet ric projects. Over the years we have observed on 58 good photometric nights , and the data obtained are used for flux calibration. Normally two or thre e OG standards are observed in every photometric night. The data are used f or getting the atmospheric extinction coefficients and instrumental magnitu de zero point. We also use these data to make inter-comparisons among the m agnitudes of these standard stars. As a result, we found the magnitudes of HD 19445, HD 84937 and BD+ 17 4708 to agree well with those estimated in pr evious work to within 0.03 magnitude. However, BD+26 2606 shows a larger de viation especially at short wavebands. Possible reasons are analyzed and th e revised magnitudes are obtained for these standards. It is shown that the quality of flux calibration of the BATC fields is significantly improved b y applying the new magnitudes.