The Catalogue of Nebulae and Clusters of Stars (CN) is an astronomical catalogue of nebulae first published in 1786 by William Herschel, with the assistance of his sister Caroline Herschel. It was later expanded into the General Catalogue of Nebulae and Clusters of Stars (GC) by his son, John Herschel, in 1864. The CN and GC are the precursors to John Louis Emil Dreyer's New General Catalogue (NGC), compiled in 1888 and used by current astronomers. Source: Wikipedia (en)