| NGC 23 | |
| Epoch: | J 2000.0 |
| Z: | 0.015231 |
| Dist Ly: | 53.21Mpc |
| Type: | SBb |
| Appmag V: | 11.9 mag |
| Absmag V: | -21.85 |
| Size V: | 1.9′ × 1.4′ |
| Names: | LEDA 698, UGC 89, Mrk 545, PGC 698, GC 9. |
NGC 23 is a spiral galaxy located in the northern constellation of Pegasus, around 53.21Mpc distant from the Milky Way. It was discovered by William Herschel on 10 September 1784. In the Webb Society Deep-Sky Observer's Handbook, 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). It is a luminous infrared galaxy with star-forming clumps.
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 to the north and east of the galactic center. It was not present on a plate taken 60 days prior.