Photometric catalog of nearby globular clusters^*

I. A large homogeneous color-magnitude diagram data-base

¹ Telescopio Nazionale Galileo, vicolo dell'Osservatorio 5, I–35122 Padova, Italy
² Dipartimento di Astronomia, Univ. di Padova, vicolo dell'Osservatorio 5, I–35122 Padova, Italy
³ Instituto de Astrofisica de Canarias, Via Lactea, E-38200 La Laguna, Tenerife, Spain

Send offprint request to: A. Rosenberg: alf@iac.es

Received: 29 July 1999
Accepted: 25 January 2000

Abstract


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 of the known Galactic globulars with  mag, cover most of the globular cluster metallicity range (), and span Galactocentric distances from to 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^nd 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  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.