Deep Hubble Space Telescope Imaging of Globular Clusters toward the Galactic Bulge: Observations, Data Reduction, and Color–magnitude Diagrams*

Abstract

Abstract The Galactic globular clusters (GGCs) located toward the Galactic bulge have generally been excluded from large-scale photometric GGC surveys due to severe total and differential extinction. Here we present an overview of a Hubble Space Telescope (HST) program designed to obtain deep, high spatial resolution multiband imaging of 16 poorly studied GGCs located toward the inner Galactic bulge and disk. In this first paper of a series resulting from these observations, we give an overview of target cluster selection, observations, and data reduction procedures for optimizing the resulting photometric catalogs. Artificial star tests are used to compare the respective advantages of different data reduction strategies in terms of photometric and astrometric precision and photometric incompleteness. We present the resulting color–magnitude diagrams (CMDs) of all target clusters in several color–magnitude planes, along with CMDs of comparison fields from parallel observations. For each target cluster, we summarize existing studies and discuss their CMDs qualitatively in the context of these results.