M13 (NGC 6205), the Great Hercules Cluster, is a globular cluster of approximately 300,000 stars that lies around 25,000 light-years away in the constellation Hercules and has an apparent magnitude of 7. This cluster is about 145 light-years in diameter. Edmond Halley discovered M13 in 1714 but it was not catalogued by Charles Messier until June 1, 1764. The galaxy that lies to the upper right of the cluster in this image is a 12th magnitude edge-on galaxy, designated NGC 6207, and halfway between NGC 6207 and M13 is the small galaxy IC4617.
Telescope: Stellarvue Raptor SVR105 @ f/7
Accessories: Stellarvue SFF7-21 flattener; Dew control by Dew Buster; Alnitak Flat-Man
Mount: Takahashi EM-200 Temma2
Camera: QSI583wsg CCD @ -10.0C
Guiding: Starlight Xpress Lodestar via PHD
Filters: Astrodon Tru-balance E-Series Generation II LRGB
Exposure: 33 x 6min.(L); 12 x 6min.(R); 15 x 6min.(G); 16 x 6min.(B); all binned 1x1
Acquisition: ImagesPlus Camera Control v4.3
Processing: Calibration, DDP in Images Plus v4.5; Registration in Registar & ImagesPlus
Post-processing: ImagesPlus 4.5; Adobe Photoshop CS5
Date(s): May 24, 25, 26, 2012
SQM reading (begin - end): N1:18.42 - 18.46; N2:18.76 - 19.23; N3:18.87 - 19.28
Temperature (begin - end): N1:78.6ºF - 70.7ºF; N2:78.8ºF - 69.4ºF; N3:79.3ºF - 72.7ºF
Location: Hendersonville, TN, USA