NGC 2403

NGC 2403
A Hubble Space Telescope (HST) image of NGC 2403 Credit: HST/NASA/ESA.
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	8 Mly (2.5 Mpc)[2]
Type	SAB(s)cd[1]
Apparent dimensions (V)	21′.9 × 12′.3[1]
Apparent magnitude (V)	8.9[1]
Other designations
HV.44,[citation needed] UGC 3918,[1] PGC 21396,[1] Caldwell 7
See also: Galaxy, List of galaxies

Coordinates: 07^h 36^m 51.4^s, +65° 36′ 09″

NGC 2403 (also Caldwell 7) is an intermediate spiral galaxy in the constellation Camelopardalis. NGC 2403 is an outlying member of the M81 Group,^[2] and is approximately 8 million light-years distant. It bears a striking similarity to M33, being about 50,000 light years in diameter and containing numerous star-forming H II regions.^[3] The northern spiral arm connects it to nearby galaxy NGC 2404.^[2] NGC 2403 can be observed using 10×50 binoculars.^[2]

Supernovae

As of late 2004, there had been two reported supernovae in the galaxy: SN 1954J, which attained a magnitude of 16 at its brightest, and SN 2004dj.

History

NGC 2403 was discovered by William Herschel in 1788. Allan Sandage detected Cepheid variables in NGC 2403 using the Hale telescope, giving it the distinction of being the first galaxy beyond our local group within which a Cepheid was discovered.^[2] He derived a distance of a mere 8 thousand light years.^[2] Today, it is thought to be a thousand times further away at about 8 million light years (3.6 Mpc).

See also

• SN 2004DJ

References

1. ^ ^{a b c d e f g h} "NASA/IPAC Extragalactic Database". Results for NGC 2403. http://nedwww.ipac.caltech.edu/. Retrieved 2006-11-21. 
2. ^ ^{a b c d e f} Kepple, George Robert; Glen W. Sanner (1998). The Night Sky Observer's Guide, Volume 1. Willmann-Bell, Inc.. p. 73. ISBN 0-943396-58-1. 
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: pp. 315–390. doi:10.1086/313041. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1997ApJS..112..315H 

External links

• Spiral Galaxy NGC 2403 at the astro-photography site of Mr. Takayuki Yoshida
• NGC 2403 at ESA/Hubble
• NGC 2403 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images