A Spectroscopic Catalog of 10 Distant Rich Clusters of Galaxies

We present spectroscopic observations of galaxies in the fields of 10 distant clusters for which we have previously presented deep imaging with WFPC2 on board the HST. The clusters span the redshift range z=0.37-0.56 and are the subject of a detailed ground- and space-based study to investigate the evolution of galaxies as a function of environment and epoch. The data presented here include positions, photometry, redshifts, spectral line strengths and classifications for 657 galaxies in the fields of the 10 clusters. The catalog comprises 424 cluster members across the 10 clusters and 233 field galaxies, with detailed morphological information from our WFPC2 images for 204 of the cluster galaxies and 71 in the field. We illustrate some basic properties of the catalog, including correlations between the morphological and spectral properties of our large sample of cluster galaxies. A direct comparison of the spectral properties of the high redshift cluster and field populations suggest that the phenomenon of strong Balmer lines in otherwise passive galaxies (commonly called E+A, but renamed here as the k+a class) shows an order-of-magnitude increase in the rich cluster environment, compared to a more modest increase in the field population. This suggests that the process or processes involved in producing k+a galaxies are either substantially more effective in the cluster environment or that this environment prolongs the visibility of this phase. A more detailed analysis and modeling of these data will be presented in Poggianti et al. (1998).