Alternative names NGC | Survey type astronomical catalog | |
Observations William Herschel, John Frederick William Herschel, James Dunlop Website vizier.u-strasbg.fr/viz-bin/VizieR?-source=VII%2F1B | ||
The New General Catalogue of Nebulae and Clusters of Stars (abbreviated as NGC) is a catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888 as a new version of John Herschel's General Catalogue of Nebulae and Clusters of Stars. The NGC contains 7,840 objects, known as the NGC objects. It is one of the largest comprehensive catalogues, as it includes all types of deep space objects and is not confined to, for example, galaxies. Dreyer also published two supplements to the NGC in 1895 and 1908, known as the Index Catalogues, describing a further 5,386 astronomical objects.
Contents
- New general catalogue meaning
- Original catalogue
- Index Catalogue
- Revised New General Catalogue
- NGC 20000
- NGCIC Project
- Revised New General Catalogue and Index Catalogue
- References
Objects in the sky of the southern hemisphere are catalogued somewhat less thoroughly, but many were observed by John Herschel or James Dunlop. The NGC had many errors, but a serious if not complete attempt to eliminate them was initiated by the NGC/IC Project in 1993, after partial attempts with the Revised New General Catalogue (RNGC) by Jack W. Sulentic and William G. Tifft in 1973, and NGC2000.0 by Roger W. Sinnott in 1988. The Revised New General Catalogue and Index Catalogue was compiled in 2009 by Wolfgang Steinicke.
New general catalogue meaning
Original catalogue
The original New General Catalogue was compiled during the 1880s by John Louis Emil Dreyer using observations from William Herschel and his son John, among others. Dreyer had already published a supplement to Herschel's General Catalogue of Nebulae and Clusters (GC), containing about 1,000 new objects. In 1886, he suggested building a second supplement to the General Catalogue, but the Royal Astronomical Society asked Dreyer to compile a new version instead. This led to the publication of the New General Catalogue in the Memoirs of the Royal Astronomical Society in 1888.
Assembling the NGC was a challenge, as Dreyer had to deal with many contradicting and unclear reports, made with a variety of telescopes with apertures ranging from 2 to 72 inches. While he did check some himself, the sheer number of objects meant Dreyer had to accept them as published by others for the purpose of his compilation. Dreyer was a careful transcriber and made few errors himself, but the catalogue nonetheless contained several errors (mostly relating to position and descriptions). He was very thorough in his referencing, which allowed future astronomers to review the original references and publish corrections to the original NGC.
Index Catalogue
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 in 1895 (IC I, containing 1,520 objects) and 1908 (IC II, containing 3,866 objects). It serves as a supplement to the NGC, and contains an additional 5,386 objects, collectively known as the IC objects. It summarizes the discoveries of galaxies, clusters and nebulae between 1888 and 1907, most of them made possible by photography. A list of corrections to the IC was published in 1912.
Revised New General Catalogue
The Revised New Catalogue of Nonstellar Astronomical Objects (abbreviated as RNGC) was compiled by Jack W. Sulentic and William G. Tifft in the early 1970s, and was published in 1973, as an update to the NGC. However, because the update had to be completed in just three summers, it failed to incorporate several previously-published corrections to the NGC data (including corrections published by Dreyer himself), and even introduced new errors.
NGC 2000.0
NGC 2000.0 (also known as the Complete New General Catalog and Index Catalog of Nebulae and Star Clusters) is a 1988 compilation of the NGC and IC made by Roger W. Sinnott, using the J2000.0 coordinates. It incorporates several corrections and errata made by astronomers over the years. However, it too ignored the original publications and favoured modern (but erroneous) corrections.
NGC/IC Project
The NGC/IC Project is a collaboration formed in 1993. It aims to identify all NGC and IC objects, and collect images and basic astronomical data on them.
Revised New General Catalogue and Index Catalogue
The Revised New General Catalogue and Index Catalogue (abbreviated as RNGC/IC) is a compilation made by Wolfgang Steinicke in 2009. It is considered one of the most comprehensive and authoritative treatments of the NGC and IC catalogues.