Since 1996 I have published on the Web a catalog of data for all known globular clusters in the Milky Way. The latest edition of the catalog is December 2010. The datafile is found here:
and the bibliography (source reference file and complete explanation of the various parameters and their calibrations) is here:
This catalog gives a list of globular cluster populations in galaxies known as of January 2013. The datafile is found here:
The catalog is published in Harris, W.E., Harris, G.L.H., and Alessi, M. 2013, ApJ 772, 82. Please refer to this paper in any use you make of the catalog.
Use this link to access the reduced data for globular cluster populations around a set of Brightest Cluster Galaxies.
This how-to manual guides you through the use of all the standard subroutines in the IRAF/PyRAF implementation of Peter Stetson's DAOPHOT code for stellar photometry on CCD images.
Elizabeth Wehner has produced a catalog of magnitudes and colors in the Sloan Digital Sky Survey system (u'g'r'i'z') for the Landolt set of standard stars all around the sky. The UBVRI magnitudes from Landolt, A.U. 1992 (AJ 104, 340) have been transformed to the SDSS system with the equations given in Fukugita, M. et al. 1996 (AJ 111, 1748). The complete catalog is here.