IC catalog
The first major update to the NGC is the Index Catalogue of Nebulae and Clusters of Stars (abbreviated as IC), published in two parts by Dreyer. It serves as a supplement to the NGC, and contains an additional 5,386 objects, collectively known as the IC objects.
Like the NGC catalog, it has undergone various revisions.
SkEye uses data from the RNGC/IC catalog maintained by Wolfgang Steinicke.