| NGC 491 | |
|---|---|
 NGC 491 imaged by the Hubble Space Telescope, showing its spiral arms | |
| Observation data (J2000 epoch) | |
| Constellation | Sculptor |
| Right ascension | 01h 21m 20.4504s |
| Declination | −34° 03′ 48.096″ |
| Redshift | 0.012902±0.0000330 |
| Heliocentric radial velocity | 3,868±10 km/s |
| Distance | 203.09 ± 7.02 Mly (62.267 ± 2.152 Mpc) |
| Apparent magnitude (V) | 13.21 |
| Characteristics | |
| Type | SB(rs)b |
| Size | ~91,900 ly (28.17 kpc) (estimated) |
| Apparent size (V) | 1.4′ × 1.0′ |
| Other designations | |
| ESO 352- G 053, GC 279, IRAS 01190-3419, MCG -06-04-011, PGC 4914 | |
NGC 491 is a barred spiral galaxy in the constellation Sculptor. Its velocity with respect to the cosmic microwave background is 3,635±19 km/s, which corresponds to a Hubble distance of 174.9 ± 12.3 Mly (53.62 ± 3.77 Mpc). However, nine non-redshift measurements give a farther mean distance of 203.09 ± 7.02 Mly (62.267 ± 2.152 Mpc). It was discovered by British astronomer John Herschel on 25 September 1834.
NGC 491 is a Seyfert II galaxy, i.e. it has a quasar-like nucleus with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, the host galaxy is clearly detectable.
