BVRI CCD photometry in the field of M 31

The final photometric calibrations are tied via the NGC 206 region to photometry taken at the Michigan-Dartmouth-MIT (MDM) 1.3m in September and October 1993. These are tied to the Landolt (1992) system of standard stars, and are in the Johnson-Kron-Cousins system (BVRcIc). Caveats: There are several known problems with the catalog.

First, there are likely to be some repeated detections of certain sources (i.e., multiple entries for the same object). Second, the wings of bright sources in some cases may be included as distinct sources. Third, the completeness limits are a strong function of position, and a much lower near the core and the core of M32.

Fourth, variable stars, blended star, and stars with cosmic ray hits, cosmetic problems or other failures may have highly abnormal colors and magnitudes. In general, we expect these problems to be small, but the user is cautioned to watch for these possible problems.