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NGC 4993 (also catalogued as NGC 4994) is an elliptical galaxy in the constellation Hydra, discovered in 1789 by Wilhelm Herschel. In August 2017, astronomers reported that the short gamma-ray burst GRB 170817A, of the sort conjectured to be emitted in the collision of two neutron stars, was detected in this galaxy.
On 16 October 2017, the team officially announced the detection of a gravitational wave, named GW170817, associated with the merger of two neutron stars. A gravitational wave event associated with this burst provided direct confirmation that binary neutron star collisions produce short gamma-ray bursts.