List of Abell clusters

The Abell catalogue is an almost complete catalogue of approximately 4,000 galaxy clusters with at least 30 members to a redshift of z = 0.2. It was originally compiled by American astronomer George O. Abell in 1958 using the plates of POSS, and extended to the southern hemisphere by Abell, Corwin and Olowin in 1987. The name 'Abell' also commonly is used as a designation for objects he compiled in a catalog of 86 planetary nebulae in 1966. The proper designation for the galaxy clusters is 'ACO' e.g. 'ACO 13'; while the planetary nebulae designation is the single letter 'A' e.g. 'A 39'.