BLUE HORIZONTAL-BRANCH STARS IN NGC-6522 AND BAADES WINDOW

We present color-magnitude diagrams in BVI (Cousins) of the globular cluster NGC 6522 in Baade's Window. Our photometry, which extends to V- 19, shows that NGC 6522 has an extended blue horizontal branch (BHB), typical of clusters of moderate metallicity close to the galactic center. We derive [Fe/H] =-1.6+/-0.2, E(B-V)0 = 0.52+/-0.05 for the cluster from comparison to the giant branches of other globulars and from the level of the cluster's horizontal branch. We identify a region in the color-magnitude diagrams which is populated mainly by BHB stars, and show that most of these are spatially concentrated around the cluster and so are not members of the bulge; the spatial density of bulge BHB stars is 0.4 arcmin-2. If the bulge has the same (1750 angstrom-V) color as the bulge of M31, then about 20% the light at 1750 angstrom is from BHB stars.