| NGC 2403 | |
|---|---|
 A Hubble Space Telescope (HST), and Subaru image of NGC 2403. NGC 2404 is visible | |
| Observation data (J2000 epoch) | |
| Constellation | Camelopardalis |
| Right ascension | 07h 36m 51.4s[1] |
| Declination | +65° 36′ 09″[1] |
| Redshift | 131 ± 3 km/s[1] |
| Distance | 9.65 Mly (2.96 Mpc)[2] |
| Apparent magnitude (V) | 8.9[1] |
| Characteristics | |
| Type | SAB(s)cd[1] |
| Apparent size (V) | 21.9′ × 12.3′[1] |
| Other designations | |
| UGC 3918,[1] PGC 21396,[1] Caldwell 7 | |
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NGC 2403 (also known as Caldwell 7) is an intermediate spiral galaxy in the constellation Camelopardalis. It is an outlying member of the M81 Group,[3] and is approximately 8 million light-years distant. It bears a similarity to M33, being about 50,000 light years in diameter and containing numerous star-forming H II regions.[4] The northern spiral arm connects it to the star forming region NGC 2404.[3] NGC 2403 can be observed using 10×50 binoculars.[3] NGC 2404 is 940 light-years in diameter, making it one of the largest known H II regions. This H II region represents striking similarity with NGC 604 in M33, both in size and location in galaxy.
- ^ a b c d e f g h "NASA/IPAC Extragalactic Database". Results for NGC 2403. Retrieved 2006-11-21.
- ^ Carlin, Jeffrey L.; Garling, Christopher T.; Peter, Annika H. G.; Crnojević, Denija; Forbes, Duncan A.; Hargis, Jonathan R.; Mutlu-Pakdil, Burçin; Pucha, Ragadeepika; Romanowsky, Aaron J.; Sand, David J.; Spekkens, Kristine; Strader, Jay; Willman, Beth (2019). "Tidal Destruction in a Low-mass Galaxy Environment: The Discovery of Tidal Tails around DDO 44". The Astrophysical Journal. 886 (2): 109. arXiv:1906.08260. Bibcode:2019ApJ...886..109C. doi:10.3847/1538-4357/ab4c32. S2CID 195218404.
- ^ a b c Kepple, George Robert; Glen W. Sanner (1998). The Night Sky Observer's Guide. Vol. 1. Willmann-Bell, Inc. p. 73. ISBN 978-0-943396-58-3.
- ^ Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W. (October 1997). "A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies". Astrophysical Journal Supplement. 112 (2): 315–390. arXiv:astro-ph/9704107. Bibcode:1997ApJS..112..315H. doi:10.1086/313041. S2CID 17086638.