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NGC 23

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NGC 23
NGC 23 imaged by the Hubble Space Telescope
Observation data (J2000 epoch)
ConstellationPegasus
Right ascension00h 09m 53.411s[1]
Declination+25° 55′ 25.46″[1]
Redshift0.015054[2]
Heliocentric radial velocity4,568 km/s[3]
Distance173.5 Mly (53.21 Mpc)[3]
Group or clusterNGC 23 Group (LGG 2)
Apparent magnitude (V)11.9 mag
Absolute magnitude (V)-21.85
Characteristics
TypeSBb[4]
Apparent size (V)2.1′ × 1.3′[2]
Other designations
LEDA 698, UGC 89, Mrk 545, PGC 698, GC 9.[2][5]

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.[6][7] In the Webb Society Deep-Sky Observer's Handbook,[8] the visual appearance of NGC 23 is described as follows:

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.[9]

NGC 23 group

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NGC 23 is part of the NGC 23 group (also known as LGG 2) that includes at least 6 other galaxies: NGC 1, NGC 26, UGC 69, UGC 79, UGC 110, and UGC 127.[10]

Supernova

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One supernova has been observed in NGC 23. SN 1955C (type unknown, mag. 16) was discovered by Allan Sandage in September 1958 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. The star was not visible on a photograph taken 60 days prior.[11][12]

References

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  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 c "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. ^ Seligman, Courtney. "New General Catalogue Objects: NGC 23". Celestial Atlas. Retrieved 11 June 2025.
  7. ^ 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 Series I. 76: 457. Bibcode:1786RSPT...76..457H.
  8. ^ Jones, K. G. (1981). Webb Society Deep-Sky Observer's Handbook. Enslow Publishers. ISBN 978-0894901348.
  9. ^ 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.
  10. ^ 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.
  11. ^ 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.
  12. ^ "SN 1955C". Transient Name Server. IAU. Retrieved 27 November 2024.
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