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Messier 3, also known as M3 or NGC 5272, is a globular cluster of stars in the northern constellation of Canes Venatici. It was discovered by Charles Messier on May 3, 1764.
M3 has an apparent magnitude of 6.2, making it a difficult naked eye target even with dark conditions. The cluster has a bright core with a diameter of about 6 arcminutes and spans a total of 12 arcminutes. This cluster is one of the largest and brightest, and is made up of around 500,000 stars. It is estimated to be 8 billion years old. Read more on Wiki

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Image details:
Telescope: TS 90/600 triplet with 2.5" TS flattener
Mount: Skywatcher HEQ5-Synscan
Camera: Atik one 6.0
Exposure: 70 * 300sec L
Software: PixInsight
Calibrationfiles: Dark:No, Bias:Yes (masterbias), Flat:Yes
 

 
(c) All photos by Ruud de Vries