M103 (NGC 1912)

M103 (NGC 1912)

M103. Image credit: NOAO/AURA/NSF.

M103 (NGC 1912) is a young, bright, remote open cluster in the constellation Cassiopeiae. It was discovered by Pierre Méchain in 1781. M103 has an estimated age of 20 million years. Most of its stars are hot and blue. However, close to the center of the cluster is a bright star (type M6 III, mag 10.8) that has evolved to the red giant stage. In binoculars, M103 is easy to find and appears as a nebulous fan-shaped patch.


visual magnitude 7.4
angular size 6.0'
linear diameter 14 light-years
distance 8,000 light-years (2,400 pc)
position R.A. 01h 33.4m,
Dec. +60° 39'
C 0129+604, OCISM 75,
OCl 326