ABELL IDENTIFICATIONS OF APM CLUSTERS OF GALAXIES

We present identifications of Abell/ACO clusters of galaxies with APM clusters using the metric separation between the APM clusters' coordinates and the nominal Abell cluster positions at both the APM and the (measured or estimated) Abell cluster redshift. Wherever available, we also take into account the positions of the APM galaxies which have redshift measurements. Finally, chance alignments of physically unrelated APM and ACO clusters at discordant redshifts are removed after inspection of the corresponding optical UK Schmidt plates. Our compilation contains only truly physical identifications, and so supersedes the identifications listed by Dalton et al. and also their subsequent erratum, which both contain a significant fraction of chance coincidences between clusters at different distances that appear close together in projection on the sky.