Caltech Faint Galaxy Redshift Survey. VIII. Analysis of the Field J0053+1234

The results of a spectroscopic investigation of a complete sample of objectswith $K_s<20$ mag in a 2 by 7.3 arcmin field at J005325+1234 are reported.Redshifts were successfully obtained for 163 of the 195 objects in the sample;these redshifts lie in the range [0.173, 1.44] and have a median of 0.58(excluding 24 Galactic stars). The redshift identifications are believed to bealmost complete for $z < 0.8$. Approximately half of the galaxies lie in fivenarrow redshift features with local velocity dispersions of $ \sim 300 km/s$.These narrow redshift ``peaks'' are primarily populated both byabsorption--line galaxies and the most luminous galaxies in the sample,although the incidence of emission lines in the luminous galaxies increaseswith redshift. The estimated dynamical masses of these redshift peaks, and thesky distribution of the galaxies within them, appear similar to groups or poorclusters of galaxies in the local universe at various stages of virialization.Some groups of galaxies therefore form at epochs $z > 1.5$, and the galaxies insuch groups appear to be coeval and to show little sign of ongoing starformation. The galaxies outside the redshift peaks are also clustered, albeitmore weakly, are less luminous and more frequently exhibit strong emissionlines. These ``isolated'' galaxies therefore appear, on average, to form starsat later epochs than the strongly clustered galaxies. The galaxy SEDs derivedfrom our $UBVRIK$ photometry are also very closely correlated with the galaxyspectral types and luminosities. These results have strong implications for theanalysis of redshift surveys at intermediate redshift.Comment: 42 pages, Latex, 11 figures, accepted for publication in the Astrophysical Journal (abstract exceeds allocated space and was truncated