NGC 23 is a spiral galaxy located in the northern constellation of Pegasus, around 173.5 megalight-years distant from the Milky Way.[3] It was discovered by William Herschel on 10 September 1784. In the Webb Society Deep-Sky Observer's Handbook,[6] the visual appearance of NGC 23 is described as follows:

NGC 23
NGC 23
NGC 23 by HST
Observation data (J 2000.0 epoch)
Right ascension00h 09m 53.411s[1]
Declination+25° 55′ 25.46″[1]
Helio radial velocity4,568 km/s[3]
Distance173.5 Mly (53.21 Mpc)[3]
Apparent magnitude (V)11.9 mag
Absolute magnitude (V)-21.85
Apparent size (V)1.9′ × 1.4′
Other designations
LEDA 698, UGC 89, PGC 698, GC 9.[2][5]

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 with NGC 9.

The shape of this galaxy is described by its morphological classification of SBb, which indicates it is a barred spiral (SB) with spiral arms that are moderately tightly wound (b).[4] It is a luminous infrared galaxy with star-forming clumps.[7]

In 1958, supernova SN 1955C was discovered in NGC 23 using the Hale Telescope. On a photographic plate taken 23 October 1955 (three years prior), a bright star with a visual magnitude around 16 was located 10 to the north and 10″ east of the galactic center. It was not present on a plate taken 60 days prior.[8]


  1. ^ a b Skrutskie, 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. ISSN 0004-6256. S2CID 18913331.
  2. ^ a b "NASA/IPAC Extragalactic Database". Results for NGC 0023. Retrieved 4 May 2010.
  3. ^ a b c Tully, R. Brent; et al. (2016). "Cosmicflows-3". The Astronomical Journal. 152 (2): 50. arXiv:1605.01765. Bibcode:2016AJ....152...50T. doi:10.3847/0004-6256/152/2/50. S2CID 250737862.
  4. ^ a b García-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. S2CID 55475658. A59.
  5. ^ "NGC 23". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 19 March 2020.
  6. ^ Jones, K. G. (1981). Webb Society Deep-Sky Observer's Handbook. Enslow Publishers. ISBN 978-0894901348.
  7. ^ Larson, K. L.; et al. (January 2020). "Star-forming Clumps in Local Luminous Infrared Galaxies". The Astrophysical Journal. 888 (2): 92. arXiv:1911.09367. Bibcode:2020ApJ...888...92L. doi:10.3847/1538-4357/ab5dc3. S2CID 208202084. 92.
  8. ^ Sandage, Allan (April 1959). "A Supernova in NGC 23". Publications of the Astronomical Society of the Pacific. 71 (419): 162. Bibcode:1959PASP...71..162S. doi:10.1086/127353.

External linksEdit