Abstract

Deep BR photometry for a large field surrounding the recently-discovered Pyxis globular cluster is presented. Our data extend 1-2 magnitudes fainter than previous studies and allow a better determination of its basic parameters, especially age. We develop a method analogous to that of Sarajedini (1994) that allows the simultaneous solution for both metallicity and reddening given BR photometry of the horizontal and giant branches. We also derive a method of metallicity determination based on the mean color of the HE (corrected for age effects). We find E(B-V)=0.21+/-0.03, [Fe/H]=-1.20+/-0.15, and an age difference of 1 Gyr relative to NGC 362. The Galactocentric distance of 41 kpc places Pyxis in the ''gap'' that Zinn's (1985) analysis indicated exists in the globular cluster system between 20 and 60 kpc. An updated analysis shows that such a gap is now much less significant. (C) 1996 American Astronomical Society.