Photometric catalog of nearby globular clusters ( I ) ? A large homogeneous ( V , I ) color - magnitude diagram data - base

We present the first part of the first large and homogeneous CCD color-magnitude diagram (CMD) data base, comprising 52 nearby Galactic globular clusters (GGC) imaged in the V and I bands using only two telescopes (one for each hemisphere). The observed clusters represent 75% of the known Galactic globulars with (m − M)V ≤ 16.15 mag, cover most of the globular cluster metallicity range (−2.2 ≤ [Fe/H] ≤ −0.4), and span Galactocentric distances from∼ 1.2 to ∼ 18.5 kpc. In this paper, the CMDs for the 39 GGCs observed in the southern hemisphere are presented. The remaining 13 northern hemisphere clusters of the catalog are presented in a companion paper. For four clusters (NGC 4833, NGC 5986, NGC 6543, and NGC 6638) we present for the first time a CMD from CCD data. The typical CMD span from the 22 V magnitude to the tip of the red giant branch. Based on a large number of standard stars, the absolute photometric calibration is reliable to the ∼ 0.02 mag level in both filters. This catalog, because of its homogeneity, is expected to represent a useful data base for the measurement of the main absolute and relative parameters characterizing the CMD of GGCs.