M-4 (NGC-6121) is one of the nearest globular star clusters in our galaxy, lying only 6200 light years from Earth. Because of this, it has a large apparent size and is easily resolved into its individual stars. It is rather loose in structure and is distinguished by having a prominent "bar" of 11th magnitude stars which bisects its center. M-4 was discovered by de Cheseaux in 1745 and cataloged by Charles Messier in 1764 as number 4. It is 70,000 light years in diameter and contains 100,000 stars.
This image, acquired on July 31, 2014, is a 35 minute integration of 3 minute 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 below ambient temperature and binned 1 X 1. Guided, captured and combined using Maxim DL5 Pro. Post processed using PhotoShop CS2, Gradient XTerminator, StarShrink, Carboni's Astro Tools and NoiseWare.