The Caldwell catalogue is an astronomical catalogue of 109 objects. It includes star clusters, nebulae, and galaxies for observation by amateur astronomers. The list was compiled by English astronomer Patrick Moore as a complement to the Messier catalogue.
The Messier catalogue is used by amateur astronomers as a list of deep-sky objects for observation. However, it was not compiled for that purpose. It does not include many of the sky's brightest deep-sky objects, such as the Hyades, the Double Cluster (NGC 869 and NGC 884), and the Sculptor Galaxy (NGC 253). The Messier catalogue was compiled as a list of known objects that might be confused with comets. As Messier got his list from observations in Paris, it did not include bright deep-sky objects visible in the Southern Hemisphere, such as Omega Centauri, Centaurus A, the Jewel Box, and 47 Tucanae.
- O'Mear, Stephen James 2002. (2002). The Caldwell Object. Cambridge University Press. ISBN 978-0-521-82796-6.
- "Caldwell Club Introduction". Retrieved 2006-09-08.
- Moore, Patrick 1995 (1995). "Beyond Messier: the Caldwell Catalog". Sky & Telescope. 90 (6): 38. Bibcode:1995S&T....90...38M. Archived from the original (subscription required) on 2009-01-16. Retrieved 2006-08-29.