A Spectroscopic Catalog of 10 Distant Rich Clusters of Galaxies

We present spectroscopic observations of galaxies in the fields of 10 distantclusters for which we have previously presented deep imaging with WFPC2 onboard the HST. The clusters span the redshift range z=0.37-0.56 and are thesubject of a detailed ground- and space-based study to investigate theevolution of galaxies as a function of environment and epoch. The datapresented here include positions, photometry, redshifts, spectral linestrengths and classifications for 657 galaxies in the fields of the 10clusters. The catalog comprises 424 cluster members across the 10 clusters and233 field galaxies, with detailed morphological information from our WFPC2images for 204 of the cluster galaxies and 71 in the field. We illustrate somebasic properties of the catalog, including correlations between themorphological and spectral properties of our large sample of cluster galaxies.A direct comparison of the spectral properties of the high redshift cluster andfield populations suggest that the phenomenon of strong Balmer lines inotherwise passive galaxies (commonly called E+A, but renamed here as the k+aclass) shows an order-of-magnitude increase in the rich cluster environment,compared to a more modest increase in the field population. This suggests thatthe process or processes involved in producing k+a galaxies are eithersubstantially more effective in the cluster environment or that thisenvironment prolongs the visibility of this phase. A more detailed analysis andmodeling of these data will be presented in Poggianti et al. (1998).