DEEP-SKY TOUR

Everybody knows the Plough, but can you find all six Messier objects in the surrounding field?

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1. M101

We start with M101, a mag. +7.9 face-on spiral galaxy also known as the Pinwheel. It's easy to find, marking the northeast point of an equilateral triangle with Mizar (Zeta () Ursae Majoris) and Alkaid (Eta (n) Ursae Majoris). M101 appears large, 20 x 15 arcminutes through a 150mm scope, which gives it a low surface brightness, but it remains relatively easy to see. A small scope shows a mottled object with uneven brightness, definitely oval with a small, central nucleus. Larger instruments give more definition to the spiral arms, revealing distinct star knots. □ SEEN IT

2. M51