The Principal Galaxies Catalog (PGC)
is a 1989 catalog of seventy thousand galaxies.
Each cataloged galaxy has a PGC identifier/number,
e.g., PGC 2557 for Andromeda.
The PGC is an enhancement to the 1983 Lyon-Meudon Extragalactic Database (LEDA),
produced at Lyon Observatory, and uses the same numbering.
The catalog, which is now an online database of over a million
galaxies, is now called HyperLEDA.
The designators, PGC and LEDA are used to specify
a galaxy by this numbering, but the maintainers of the catalog
suggest using J designators.