A NEW REDUCTION OF THE BLANCO COSMOLOGY SURVEY: AN OPTICALLY SELECTED GALAXY CLUSTER CATALOG AND A PUBLIC RELEASE OF OPTICAL DATA PRODUCTS

The Blanco Cosmology Survey is a four-band (griz) optical-imaging survey of similar to 80 deg(2) of the southern sky. The survey consists of two fields centered approximately at (R.A., decl.) = (23(h), -55 degrees) and (5(h)30(m), -53 degrees) with imaging sufficient for the detection of L-star galaxies at redshift z <= 1. In this paper, we present our reduction of the survey data and describe a new technique for the separation of stars and galaxies. We search the calibrated source catalogs for galaxy clusters at z <= 0.75 by identifying spatial over-densities of red-sequence galaxies and report the coordinates, redshifts, and optical richnesses, lambda , for 764 galaxy clusters at z <= 0.75. This sample, >85% of which are new discoveries, has a median redshift of z = 0.52 and median richness lambda (0.4L L-star) = 16.4. Accompanying this paper we also release full survey data products including reduced images and calibrated source catalogs. These products are available at http://data.rcc.uchicago.edu/dataset/blanco-cosmology-survey.