NGC 6522 : an intermediate metallicity globular cluster projected on the baade window

Abstract

We studied NGC 6522 colour magnitude diagrams using CCD photometry with BV filters. We have carefully estimated the reddening, which is criticai for Baade Window studies, obtaining E(B-V) = 0.55. We derive for this intermediate metallicity cluster, a distance of 6.2 kpc, slightly foreground to the bulk of the metal-rich bulge population. The CMD properties of the cluster core show an enhanced and extended blue horizontal branch, a characteristic in common with many other core collapsed globular clusters.