M13 - Hercules Globular Cluster

by Chuck September 18, 2009

Tonight was a beautiful clear night, so I set the telescope up to try to get a look at M13 through our little 3-inch reflector. Two weeks ago at the Everett Astronomical Society's open scope night we'd seen M13 through a 16-inch Dobsonian telescope, a view that made the cluster look like the picture from the Hubble Space Telescope (here on Wikipedia). That night I'd went outside with binoculars and took a look, through the 7x50's M13 was little more than a smudge on the lens, but I could see it.

I was certain it wouldn't look anything like the 16-inch Dob in our scope, but the telescope would make it appear better than the binoculars, I was sure.

M13 is in Hercules, about 2/3rds of the way between the bottom two stars of the trapezoid (40ZetaHer and  44EtaHer according to Pocket Stars). I star-hopped from the tree line near Arcturus up to Hercules -- finding M13 was pretty easy since there was a straight line of bright stars from the tree line to the trapezoid. Once I'd found the trapezoid, finding M13 was easy.

Through the 16-inch reflector M13 appeared as a bright cluster of stars, the central cluster showing individual stars and thinning out toward the edges. Through the 7x50 binoculars the cluster appears as a bright smudge against the black sky, but with little detail. Through the 3-inch reflector I still can’t make out any individual stars in the cluster, but I can begin to see that it is round, bright in the middle and thinning toward the outside.

According to Wikipedia M13 is just visible to the naked eye on a clear night. I haven’t been able to pick it out yet, but since this is an easy to find Messier object, I’ll keep trying.

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Backyard Astronomy

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