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NGC 2403

Proper NameNone
Caldwell NumberC7
NGC/IC NumberNGC 2403
Right Ascension7h 36m 51s
Declination+65° 36' 9"
Distancec.10,400,000 light years
c.3,200,000 parsecs
MagnitudeApparent: +8.25
Absolute: -19.28
DiameterApparent: 19.9'
Actual: 60,700 light years
Hubble TypeSABc intermediate spiral
Optimum VisibilityJanuary / February (Usually visible from northern latitudes)
NotesLike many galaxies, this intermediate spiral has smaller companion galaxies associated with it. In the case of C7, two such attendant galaxies are known, both dwarf spheroidal galaxies, individually designated DDO 44 and MADCASH-1. DDO 44 is in the process of interacting directly with its parent galaxy, and is being stretched and distorted by the gravitational influence of C7.

One of a pair of spiral galaxies in the Caldwell catalogue that fall within the large but sparse northern constellation of Camelopardalis (the other being C5, the Hidden Galaxy, far to the west). This is an area of the sky lacking bright stars, westward of the Plough and Ursa Major.

Imagery provided by Aladin sky atlas

C7 is seen from Earth at an oblique angle, making its multiple spiral arms clearly visible. This is a comparatively small spiral galaxy (with a diameter of some sixty thousand light years, it is only about half the size of the Milky Way). C7's arms are dotted with H II regions where star formation is taking place. One of these star-forming regions is truly immense: desginated NGC 2404, it connects to C7's northernmost spiral arm, and measures nearly a thousand light years from side to side. C7 is also notable as being the first galaxy outside the Milky Way in which Cepheid variables were positively identified.

On a galactic scale, C7 lies relatively close to the Milky Way, at a distance of just over ten million light years. It represents an outlying member of the M81 Group, a group of galaxies centred around Bode's Galaxy, M81, which lies within Ursa Major to the east.


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