Astron. Astrophys. Suppl. Ser. 144, 5-38

Photometric catalog of nearby globular clusters

I. A large homogeneous (V,I) color-magnitude diagram data-base

A. Rosenberg ¹ - G. Piotto ² - I. Saviane ² - A. Aparicio ³

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

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

Received July 29, 1999; accepted January 25, 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 $75\%$ of the known Galactic globulars with $(m-M)_V\leq 16.15$ mag, cover most of the globular cluster metallicity range ( $-2.2 \leq {\rm [Fe/H]}\leq -0.4$), and span Galactocentric distances from $\sim1.2$ to $\sim18.5$ 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 $22^{\rm nd}$ 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 $\sim0.02$ 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.

Key words: astronomical data base: miscellaneous -- catalogs -- stars: Hertzsprung-Russel (HR) -- stars: population II -- globular clusters: general