M103 (NGC 581) is a open cluster located within the constellation Cassiopeia, in the Perseus Arm of the Milky Way Galaxy. in the Local Group of galaxies.
M103 is best viewed during winter, is magnitude 7.0*, and can be viewed with binoculars. It is 6' in size. For reference, the full moon is 30' (arc minutes) in size.
* The naked eye can see up to magnitude 8 objects under ideal dark sky conditions.
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