Sky and Telescope – Tonight’s sky at a glance.

Indexes to celestial objects.

• NGC Catalog query (SEDS) Use this to query NGC, Messier, and IC objects.

The New General Catalog was created as an update of the General Catalog by Sir John Herschel. The NGC was compiled in the end of the 19th Century and indexed objects that were found on photographic plates of the time. This catalog now contains over 13,000 objects. The link provided here is an interactive NGC database.

• Messier Catalog

The Messier catalog was compiled by the French astronomer Charles Messier (1758-1782) to distinguish celestial objects from comets. Comet discovery was a means of fame at that time. The original list contained about 100 objects that one could reference to ensure whether or not it was a comet. Today, it is used extensively by astronomers everywhere (especially amateurs). Often, Messier marathons are undertaken in which the goal is to find as many Messier objects as one can in one nightly observing session.

• Caldwell Catalog

The Caldwell Catalogue is an astronomical catalog of 109 star clusters, nebulae, and galaxies for observation by amateur astronomers. The list was compiled by Sir Patrick Caldwell-Moore, better known as Patrick Moore, as a complement to the Messier Catalogue.^[1] The Messier Catalogue is used by amateur astronomers as a list of deep-sky objects for observations, but Moore noted that the list did not include many of the sky’s brightest deep-sky objects,^[1] including the Hyades, the Double Cluster (NGC 869 and NGC 884), and NGC 253. (WikiPedia, 2013).

• Arp catalog (Atlas of Paculiar Galaxies):

This catalogs galaxies of peculiar structures. Compiled by Halton Arp, it has 338 galaxies listed.