METAL-RICH GIANT BRANCHES OF BULGE CLUSTERS - APPLICATION TO COLOR-MAGNITUDE DIAGRAMS OF M31 AND M32

Color-magnitude diagrams for the metal-rich bulge clusters NGC 6528, NGC 6553, and Terzan 1 are calibrated in M(I0) versus (V-I)0, and compared to that of 47 Tuc. In such diagrams the blanketing effects for increasing metallicities are directly estimated. Such studies are important for the interpretation of CMDs of metal-rich populations in Local Group external galaxies. We compare our results to literature color-magnitude diagrams of M31 and M32 bulges. The available CMDs are not deep enough to reveal the metal-rich populations similar to that of NGC 6553, which indicates that the determinations of average metallicities from the giant branch width in the M31 and M32 fields are lower limits.