NGC 6331

NGC 6331 is a type E elliptical galaxy located in the Ursa Minor constellation. It is located 737 million light-years from the Solar System and was discovered by German-British astronomer William Herschel on December 20, 1797, utilizing an 18.7-inch f/13 spectrum telescope but also observed by Guillaume Bigourdan.
With an approximate diameter of 345,000 light-years, NGC 6331 is well considered one of the largest galaxies. It is the brightest group member of Abell 2256 and first in 6' string to the east, making up of 6 galaxies. NGC 6331 also makes up a part of the galactic triplet CGCG 355-024 which comprises two other elliptical galaxies in the cluster, CGCG 355-024 NED03 and CGCG 355-024 NED01.