THE PALOMAR DISTANT CLUSTER SURVEY .1. THE CLUSTER CATALOG

We present an optical/near-IR selected catalog of 79 clusters distribu ted over an area of 5.1 degrees sq. The catalog was constructed from i mages obtained with the 4-Shooter CCD mosaic camera on the Hale 5 m te lescope operating in ''scan'' mode. The survey, hereafter known as the Palomar distant cluster survey (PDCS), was conducted in two broadband filters that closely resemble V and I. The 4 sigma limiting magnitude s for our 300 s exposures are similar to 23.8 (V) and 22.5 (I). A matc hed filter algorithm was developed and employed to identify the cluste r candidates by using positional and photometric data simultaneously. The clusters cover the range 0.2 less than or equal to z less than or equal to 1.2, based on the redshift estimates derived in the cluster d etection procedure. An accurate selection function is generated from e xtensive simulations. We find that the cumulative surface density of c lusters with richness class R greater than or equal to 1 is about a fa ctor of 5 higher than the extrapolated density of R greater than or eq ual to 1 Abell clusters. The PDCS results are consistent with a consta nt comoving density of clusters to z less than or equal to 0.6, albeit at the above high density level. Constraints on cluster abundances at z>0.6 will be possible with the acquisition of spectroscopic redshift s for a large subset of these cluster candidates. We also present a su pplemental catalog of 28 clusters that do not satisfy all our selectio n criteria but which include some of the most distant systems detected in the survey. Finding charts for all 107 cluster candidates are prov ided. (C) 1996 American Astronomical Society.