Searching the Caldwell Galaxies

Abstract

Not everyone likes the term Caldwell catalogue. It was a catalogue devised in 1995 by the British amateur astronomer, prolific author, and TV personality Sir Patrick Moore in an attempt to list all of the “easy” deep sky objects not catalogued by Charles Messier in his 18th century catalogue. Although the Messier catalogue objects are some of the easiest for Northern Hemisphere astronomers to hunt down, the catalogue is not exhaustive and there are quite a few objects that Messier appears to have overlooked. In addition, there are quite a few that would have been difficult, or impossible, to observe from his Paris site. Thus, Patrick decided to emulate Messier’s original 109-object catalogue and list his own favorite 109 objects that were not included in Messier’s list. The name Caldwell was used because “Moore” would mean an “M” designation and Messier had already used “M.” Patrick’s surname is actually double-barrelled (i.e., Caldwell-Moore), so he used the Caldwell part and his objects have a “C” designation. There was never any claim that Patrick had discovered these objects, which seems to be the unfair comment that a few people have made regarding the name. They already have mainly NGC (New General Catalogue) designations. Patrick was just extending the list of easy-to-see deep sky objects beyond Messier, and the Caldwell catalogue has actually proved to be highly popular; even telescope hand controllers now feature keypads with Caldwell designations. Caldwell objects are listed in order of decreasing declination, which is far more useful than the Messier designations.