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 { [ Fe / H ] } \leq - 0.4 ) , and span Galactocentric distances from \sim 1.2 to \sim 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 ^ { 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 \sim 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 .