M 103

M103 is one of the "latest additions" (together with M101 and 102) which Messier included from Mechain's report, but had not the time to observe before publication.

This cluster of at least 40 proven members is one of the more remote open clusters in Messier's catalog, at about 8,000 light years. Its appearance is dominated by the non-member binary Sigma 131 (components A, 7.3 mag, and B, 10.5 mag, seperated 13.8" in PA 142, at 1956). The 2 brightest cluster members are a B5 Ib supergiant and a B2 III giant, while the lot of main sequence stars indicate an age of about 9 million years, according to Cecilia Payne-Gaposhkin's "Stars and Clusters".

Right ascension	01 : 29.9 (hours : minutes)
Declination	+60 : 27 (degrees : minutes)
Distance	8.0 (light-years*10^3)
Visual magnitude	7.4