Telescope Reviews: Finding M101 - the Pinwheel Galaxy

M101 is another good, but often challenging, binocular target in Ursa Major. It's a relatively large (46'), diffuse object that will sink into the background unless you have reasonably dark skies. Again, it helps a lot to know precisely where this object is located to confirm its capture.

As a rough guide, you can form a triangle that is a bit flatter than an equilateral triangle with Alkaid and Mizar, but I've often found myself scanning the region in vain to find M101 when the skies are lighter than normal (for this viewing location), so a more accurate star hop is helpful.

Start at Mizar and a line through Mizar and Alcor points to the first of four stars in an irregular line, each about a degree apart. After you hit the first star, angle back a bit, more towards Alkaid, and count 1,2,3,4 - they're pretty bright stars and quite obvious.

At the fourth star, take a right-angle turn away from Alkaid and start counting 1..2 with a pair of close stars that form the upper corner of what looks like a miniature Hercules Keystone. Counting in the same direction 3..4..5, M101 is just to the right of stars 4 & 5, about 15' away.

I have no trouble seeing M101 with my 10x42mm binoculars under dark skies (5.5-6 mag), but if the background gets much brighter than that, it rapidly disappears and requires larger binoculars to find it.

A good source of background information on M101 can be found at this web page.

Again, good luck hunting for m101!

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