Alt. Designations: NGC 581
Object Type: Open Cluster
Constellation: Cassiopeia
Distance: 8.5 kly
Right Ascension: 01h 33m 23.0s
Declination: +60° 39´ 00"
Visual Magnitude: 7.4
Apparent Dimension: 6.0´ Dia.
Best Month To View: Oct

M103 is one of the latest additions to the Messier catalog. It was discovered by Pierre Mechain and included in the catalog before Messier had a chance to observe it directly. It was also the last object to be included in the first publication of Messier's catalog. This is an open cluster of stars situated in the constellation of Cassiopeia. It consists of about 40 stars located some 8,000 light-years from Earth. Visually, M103 is said to form an arrowhead shape. This bright cluster is an easy target for a pair of binoculars. A small telescope will be able to resolve the cluster's fainter stars.