M3 – Globular Cluster


Messier 3 is a globular cluster in the constellation Canes Venatici at a distance of 33,900 light-years away from Earth with a magnitude of 6.2. It is one of the largest and brightest globular clusters visible in the northern hemisphere, and consists of around 500,000 stars. Globular clusters are groups of old stars with this cluster being estimated at 8 billion years old. Within this cluster are a known 274 variable stars – the most found within any globular cluster.
‘X’ marks the location of M3.
I happened to be out viewing this cluster as the moon was already beyond 50% so it was washing out a lot of the stars, galaxies, and nebula in the sky. I decided on M3 as it is one of the brightest globulars, and it was one of the few that was above my tree line from the backyard. Considering the moon brightness paired with light pollution I was very impressed with the view of it through the telescope, and of course couldn’t resist getting a few images of it to stack and show off.
Given it’s location along the border of 3 constellations; Canes Venatici, Bootes, and Coma Berenices it wasn’t the easiest to find due to it’s location in the sky and it’s lack of many stars visible to guide from. This was the first time I actually used my RA and DEC dials on my EQ mount. Using the star Arcturus as my setting star I tried it a few times with success on each attempt making M3 land within the view each time.
M3 Globular Cluster in Canes Venatici. April 2, 2012. Also above the cluster is Galaxy NGC 5263 at magnitude 14.
This consists of 14 images at 30 seconds a piece, 10 dark frames and 20 bias frames taken on April 2, 2012. Since the temperature at night has been the same during the last few sessions I’m able to reuse the same darks, and bias frames each time. I planned on getting a few more dark frames while I was out, but I had some difficulties with my polar alignment and tracking that I was getting a lot of star trails. By the time I finally got everything the way I needed it to be I was almost out of battery on my camera.

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