NGC 4993
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 | |
|---|---|
NGC 4993 and GRB 170817A afterglow as taken by Hubble Space Telescope | |
| Observation data (J2000 epoch) | |
| Constellation | Hydra |
| Right ascension | 13h 09m 47.7s |
| Declination | −23° 23′ 02″ |
| Redshift | 0.009727 |
| Heliocentric radial velocity | 2916 km/s |
| Distance | 44.1 Mpc (144 Mly) |
| Group or cluster | NGC 4993 Group |
| Apparent magnitude (V) | 13.32 |
| Characteristics | |
| Type | (R')SAB0^-(rs) |
| Size | ~55,000 ly (17 kpc) (estimated) |
| Apparent size (V) | 1.3 x 1.1 |
| Notable features | Host of neutron star merger detected as gravitational wave GW170817 and gamma-ray burst GRB 170817A |
| Other designations | |
| NGC 4994, ESO 508-18, AM 1307-230, MCG -4-31-39, PGC 45657, WH III 766 | |
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.
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