Streaming motions of galaxy clusters within 12 000 km s-1 -- I. New spectroscopic data

Abstract

We present new spectroscopic data for 532 early-type galaxies, predominantly Abell cluster members with cz < 12 000 km s−1. We tabulate 919 individual measurements, from six observing runs, for recession velocity, cz, central velocity dispersion, σ, and magnesium line-strength indices, Mg2 and Mgb. The median estimated error, per measurement, in σ is 5 per cent. The Mg2 line-strength data have median errors of 0.009 mag. The observed scatter between repeat measurements is largely accounted for by photon-counting errors. These data will be employed in forthcoming papers, where they will form part of a merged and standardized catalogue of Fundamental Plane data for use in cluster distance estimates and peculiar velocity analyses.