NGC 4993 (also catalogued as NGC 4994 in the New General Catalogue) is a lenticular galaxy located about 140 million light-years away in the constellation Hydra. It was discovered on 26 March 1789 by William Herschel and is a member of the NGC 4993 Group.NGC 4993 is the site of GW170817, the first astronomical event detected in both electromagnetic and gravitational radiation, the collision of two neutron stars, a discovery given the Breakthrough of the Year award for 2017 by the journal Science. Detecting a gravitational wave event associated with the gamma-ray burst provided direct confirmation that binary neutron star collisions produce short gamma-ray bursts.

400/500mm - 17.5" (4/13/96): fairly faint, fairly small, round, 1.0' diameter. Pretty symmetrical appearance increasing to a 30" brighter core and a 10" nucleus. Located 5.3' WNW of mag 8.5 SAO 181423 and 20' SE of mag 5 Psi Hydrae.