M-71 (NGC-6838)

M-71 (NGC-6838)

M-71 (NGC-6838) A globular star cluster located in the constellation of Sagitta, The Arrow, midway between the stars Delta and Gamma Sagittae. M-17 is 12,000 light years from Earth and is 27 light years in diameter.
It was long thought to be an extremely dense open cluster, but modern photometric research has detected a short "horizontal branch" in the Hertzsprung-Russel diagram of the stars found in M-71, lending credibility to the fact that is IS, in fact, a loosely structured globular cluster. M-71 was discovered by Philippe de Cheseaux in 1745, and included by Charles Messier in his catalog in 1780 as number 71.
This image, acquired on August 11, 2013, is a 15 minute integration of 60 second exposures through the Celestron C-11 at f/2, using the HyperStar III imaging system and the Starlight Express SXVR-H694C color CCD camera, operating at -10 degrees below ambient temperature and binned 1 X 1. Guided, captured and combined using Maxim DL5 Pro. Post processed using PhotoShop CS, Gradient XTerminator, StarShrink, Carboni's Astro Tools and NoiseWare.