Bright, extended ellipse; a bright nuclear structure is noticeably elongated; two weak spiral enhancements emerge from opposite sides of the nucleus, one curving towards a bright star attached on the south end. The galaxy is likely interacting withNGC 9.
Onesupernova has been observed in NGC 23. SN 1955C (type unknown, mag. 16) was discovered byAllan Sandage in September 1958 using theHale Telescope. On a photographic plate taken 23 October 1955 (three years prior), a bright star with a visual magnitude around 16 was located10″ to the north and10″ east of thegalactic center. The star was not visible on a photograph taken 60 days prior.[11][12]
^abSkrutskie, Michael F.; Cutri, Roc M.; Stiening, Rae; Weinberg, Martin D.; Schneider, Stephen E.; Carpenter, John M.; Beichman, Charles A.; Capps, Richard W.; Chester, Thomas; Elias, Jonathan H.; Huchra, John P.; Liebert, James W.; Lonsdale, Carol J.; Monet, David G.; Price, Stephan; Seitzer, Patrick; Jarrett, Thomas H.; Kirkpatrick, J. Davy; Gizis, John E.; Howard, Elizabeth V.; Evans, Tracey E.; Fowler, John W.; Fullmer, Linda; Hurt, Robert L.; Light, Robert M.; Kopan, Eugene L.; Marsh, Kenneth A.; McCallon, Howard L.; Tam, Robert; Van Dyk, Schuyler D.; Wheelock, Sherry L. (1 February 2006)."The Two Micron All Sky Survey (2MASS)".The Astronomical Journal.131 (2):1163–1183.Bibcode:2006AJ....131.1163S.doi:10.1086/498708.ISSN0004-6256.S2CID18913331.
^abGarcía-Lorenzo, B.; et al. (January 2015). "Ionized gas kinematics of galaxies in the CALIFA survey. I. Velocity fields, kinematic parameters of the dominant component, and presence of kinematically distinct gaseous systems".Astronomy & Astrophysics.573: 43.arXiv:1408.5765.Bibcode:2015A&A...573A..59G.doi:10.1051/0004-6361/201423485.S2CID55475658. A59.
^Herschel, William (1786). "Catalogue of One Thousand New Nebulae and Clusters of Stars. By William Herschel, LL.D. F. R. S.".Philosophical Transactions of the Royal Society of London.76: 457.Bibcode:1786RSPT...76..457H.
^Garcia, A. M. (1993). "General study of group membership. II. Determination of nearby groups".Astronomy and Astrophysics Supplement Series.100: 47.Bibcode:1993A&AS..100...47G.
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