Index Catalogue
The IC catalogue (Index Catalogue, 1895–1908) is an extension to the NGC, compiled by John Dreyer. It contains more than 5,000 additional nebulae, star clusters and galaxies that became detectable with improved photographic plates and telescopes at the turn of the 20th century. Like the NGC, the IC is not a curated list of notable objects, but a systematic inventory of all non‑stellar sources that could be reliably identified with the observational technology of that era.
