Messier 103 (NGC 581) is Cassiopeia’s second Messier-designated open cluster, after Messier 52. As such it’s an impressive-looking object, although it’s often neglected in favour of the aforementioned M52 and the marvellous ET Cluster (NGC 457) and Caroline’s Rose (NGC 7789). Nonetheless, observers slewing its method might be delighted by what they see.
Messier 103 has an built-in magnitude of +7.4 and could be very simple to find by means of 10 x 50 binoculars mendacity only a diploma north-east of Ruchbah (beta [b] Cassiopeiae; magnitude +2.7), one of many stars in Cassiopeia’s acquainted ‘W’ asterism. As darkness falls in early October, Cassiopeia, which is circumpolar from UK shores, is over 50 levels excessive within the east. Messier 103 sits excessive overhead by midnight BST (01:00 UT) and might be noticed for the rest of the lengthy night time.
By way of a small telescope M103 reveals a particular fan form, oriented south-east to north-west throughout an obvious diameter of round 6’. A 150mm (six-inch) telescope can pick round 15 stars of its full complement of practically 200. Photos reveal a splash of color from the magnitude +8.5 crimson star close to the centre of M103.
Messier 103 lies 8,130 gentle years away and is a really younger, metal-rich cluster fashioned about 25 million years in the past. It was found by Pierre Méchain, in 1781.
