New General Catalogue
The NGC contained multiple errors, but attempts to eliminate them were made by the "Revised New General Catalogue" (RNGC) by Jack W. Sulentic and William G. Tifft in 1973, "NGC2000.0" by Roger W. Sinnott in 1988, and the "NGC/IC Project" in 1993. A "Revised New General Catalogue and Index Catalogue" (abbreviated as RNGC/IC) was compiled in 2009 by Wolfgang Steinicke and updated in 2019 with 13957 objects.