New General Catalogue

The New General Catalogue of Nebulae and Stars is a large catalogue of deep sky astronomical objects based on the General Catalogue of Nebulae and Stars created by William Herschel.[1] Produced by John Louis Emil Dreyer in 1888, the New General Catalogue is an extension of the catalogue made by Herschel containing several thousand objects, including galaxies, nebulae and open clusters among others. Later, Dreyer published two supplementary catalogues, the Index Catalogues. There are some mistakes in the New General Catalogue, mainly position and description errors and others have tried to correct them. The most recent was the Revised New General Catalogue and Index Catalogue performed by Wolfgang Steinicke in 1996.[1]

The NGC catalogue is still widely used by astronomers today. Objects in the New General Catalogue are identified by the letters "NGC" followed by a number.

## History[edit]

The NGC catalogue was first published in 1888 and contains some 7,840 objects.[1][2] This was an attempt by Dreyer to collate all the known objects, such as nebulae and globular clusters, into a single catalogue. Previously, there had been many catalogues, including some famous ones such as the Messier catalogue, but these were becoming outdated as more powerful telescopes allowed for the observation of fainter deep sky objects. As an example, Messier's catalogue from 1771 contains around 100 objects whilst John Herschel's General Catalogue created in 1864 contains some 5,079 objects.[1][3] Later catalogues did not also include all previously known objects. Herschel specifically tried to avoid including entries in the Messier Catalogue in his.[4] Dreyer used any source of data he could find. As this meant data was collected by numerous people, using numerous different instruments, various observation conditions, this led to various errors in the NGC catalogue. Some entries are repeated and others point to blank patches of sky.

After publishing the New General catalogue, Dreyer published the Index catalogues, the first in 1895 and the second in 1908. Denoted as IC I and IC II, these added a further 1,520 and 3,866 objects.[1]

## References[edit]

1. ↑ 1.0 1.1 1.2 1.3 1.4 NGC/IC Catalogues from freestarcharts.com
2. ↑ NGC/IC Mission from ngcicproject.org
3. ↑ Charles Messier's Catalog of Nebulae and Star Clusters from messier.seds.org
4. ↑ William Herschel's catalog of Deep Sky objects from messier.seds.org

## See also[edit]

* Messier catalogue
* Interactive NGC Catalogue Online