Arecibo General Catalog

The Arecibo General Catalog (AGC) is a catalog of galaxies specifically formed to support studies carried out using Arecibo Observatory, such as ALFALFA. The catalog's galaxy id number is the Uppsala General Catalogue (UGC) id number if it exists, and is a number beyond the UGC number range for other galaxies. The prefix AGC with this id number is sometimes used for galaxy designators.

Be aware that the AGC prefix is also sometimes used to refer to the Abell Catalog of galaxy clusters and given these two usages of the prefix, it seems possible that the same designator has been used for both a galaxy and a (likely-unrelated) galaxy cluster.