How to find the M103 Open Cluster in Cassiopeia (An Easy to Find Cluster)

M103 is an easy to find open cluster in the Cassiopeia constellation, which as it is a circumpolar constellation is visible all year around to observers in the northern hemisphere.

In fact, M103, was one of the last additions to the world famous Messier Catalogue, but unusually not to catalogued by Messier himself. Instead it was listed by French astronomer Pierre Méchain in March or April 1781.

Click to enlarge the M103 star chart

The open cluster M103 is so easy to find because it is right next to a bright star in the very recognizable constellation Cassiopeia which looks like a giant 'W'. Once you locate Cassiopeia, M103 can be located one degree east of the star Ruchbah the bottom-left star the 'W' you are shown in this star map.

M103 is visible in binoculars where it will look light a faint fuzzy patch, with a telescope of four inches or more and the four brightest stars of the cluster will be visible. While larger telescopes resolve even more stars across this cluster. However, as the cluster is quite loose and as it is one of the smaller open clusters with only a hundred seventy-two confirmed stars, and there are many background stars in this part of the night sky, a large telescope may make M103 more difficult to make out.

If you are interested in observing other clusters there are some great clusters to observe in the summer triangle. To see what the M103 cluster looks like through an eyepiece please watch the episode below.

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