Redshifts and Velocity Dispersions of Galaxy Clusters in the Horologium-Reticulum Supercluster

We present 118 new optical redshifts for galaxies in 12 clusters in theHorologium-Reticulum supercluster (HRS) of galaxies. For 76 galaxies, the datawere obtained with the Dual Beam Spectrograph on the 2.3m telescope of theAustralian National University at Siding Spring Observatory. After combining 42previously unpublished redshifts with our new sample, we determine meanredshifts and velocity dispersions for 13 clusters, in which previousobservational data were sparse. In six of the 13 clusters, the newly determinedmean redshifts differ by more than 750 km/s from the published values. In thecase of three clusters, A3047, A3109, and A3120, the redshift data indicate thepresence of multiple components along the line of sight. The new clusterredshifts, when combined with other reliable mean redshifts for clusters in theHRS, are found to be distinctly bi-modal. Furthermore, the two redshiftcomponents are consistent with the bi-modal redshift distribution found for theinter-cluster galaxies in the HRS by Fleenor et al. (2005).Comment: 13 pages, 3 figures, Accepted to A