Focus on Messier 106  


Messier 106 is a superb spiral galaxy in Canes Venatici. Image: David Wills.

Sniff out the Hunting Dogs (Canes Venatici), the home of the magnificent Whirlpool Galaxy (M51) in the far northern sky, and you’ll find more galaxies than you can shake a stick at. Prominent Messier 106 (NGC 4258) is a superb spiral galaxy that holds its own in the company of the likes of the Sunflower Galaxy (M63) and M94. It’s bright enough to be found through a pair of binoculars and it looks like a galaxy through even a small telescope.   

M106 lies in the north-western corner of Canes Venatici, 7.5° south-east of Phecda (gamma Ursae Majoris), the star at the south-eastern corner of the Plough’s ‘bowl’. AN graphic by Greg Smye-Rumsby.

Where to look

Messier 106 is located in the north-western corner of Canes Venatici; sweep with a pair of 10 x 50 binoculars 1.7° south of the star 3 Canum Venaticorum (magnitude +5.2) and on a fine night you should spot a faint smudge of light. M106 is circumpolar (never setting) from UK shores, culminating late-month almost at the zenith at about midnight GMT.

An 80mm telescope (three-inch) can show its elongated disc, orientated south-east to north-west, while upgrading to a 150mm (six-inch) reveals a slightly mottled, oval-shaped core extending to perhaps 10’ x 7’, with a well-defined nucleus surrounded by a faint outer halo of nebulosity.

The Hubble Space Telescope’s magnificent take on M106. Image: NASA, ESA, the Hubble Heritage Team (STScI/AURA) and Robert Gendler.

A big galaxy

Messier 106 is a large galaxy comparable in size with the Andromeda Galaxy (M31), and has somewhat of a resemblance to it. Its physical diameter of 135,000 light years at its neighbouring distance of 24 million light years give it a large apparent diameter on the sky of 18’ x 7.9’. M106 is a strong source of radio waves from its an active core, giving it a Seyfert II classification.

Amateurs now routinely capture superb images of M106 and widefield data can show a number of much smaller galaxies, including NGC 4217, an attractive edge-on spiral with a notable dust line that’s visible through a 200mm (eight-inch) telescope, and, closer in to M106, NGC 4248, a smaller still irregular that can be picked up through a 300mm (12-inch) ‘scope.