| NGC 691 | |
|---|---|
 NGC 691 by the Liverpool Telescope | |
| Observation data (J2000epoch) | |
| Constellation | Aries |
| Right ascension | 01h 50m 41.7s[1] |
| Declination | +21° 45′ 36″[1] |
| Redshift | 0.008889 ± 0.000013[1] |
| Heliocentric radial velocity | 2,665 ± 5km/s[1] |
| Distance | 119 ± 14Mly (36.5 ± 4.3Mpc)[1] |
| Apparent magnitude (V) | 11.5[2] |
| Characteristics | |
| Type | SA(rs)bc[1] |
| Apparent size (V) | 3.5′ × 2.6′[1] |
| Other designations | |
| UGC 1305, CGCG 482-023,MCG +04-05-019,PGC 6793[1] | |
NGC 691 is anunbarred spiral galaxy located in the constellationAries. It is located at a distance of circa 120 millionlight years from Earth, which, given its apparent dimensions, means that NGC 691 is about 130,000 light years across. It was discovered byWilliam Herschel on November 13, 1786.[3]
NGC 691 features a multiple ring structure, with three rings recognised in theinfrared, with diameters of 1.03, 1.67, and 2.79 arcminutes.[4] When imaged inH-alpha, the galaxy appears patchy. The totalstar formation rate of the galaxy is estimated to be about 0.6M☉ per year.[5] Onesupernova has been observed in NGC 691, SN 2005W. It was discovered by Yoji Hirose in unfilteredCCD frames taken on Feb. 1.442 UT with a 0.35-m f/6.8Schmidt-Cassegrain reflector. The supernova was located 56" east and 1" south of the center of NGC 691 and at the time of the discovery had anapparent magnitude of 15.2.[6] Spectrographic observations indicated it was atype Ia supernova about a week before maximum.[7] The peak magnitude of the supernova was 14.3, on February 10.759.[8]
NGC 691 is the foremost member of agalaxy group known as the NGC 691 group. Other members of the group includeIC 163,NGC 678,NGC 680,NGC 694,IC 167, andNGC 697.[9]
Media related toNGC 691 at Wikimedia Commons