| NGC 3198 | |
|---|---|
 NGC 3198 imaged by theNicholas U. Mayall Telescope | |
| Observation data (J2000epoch) | |
| Constellation | Ursa Major |
| Right ascension | 10h 19m 55.0022s[1] |
| Declination | +45° 32′ 59.337″[1] |
| Redshift | 0.00227[2] |
| Distance | 47Mly[3] |
| Apparent magnitude (V) | 10.3[4] |
| Characteristics | |
| Type | SB(rs)c[4] |
| Size | ~121,800 ly (37.33 kpc) (estimated)[1] |
| Apparent size (V) | 8.5′ × 3.3′[4] |
| Other designations | |
| IRAS 10168+4548,UGC 5572,MCG +08-19-020,PGC 30197,CGCG 240-030[2] | |
NGC 3198, also known asHerschel 146[5] is abarred spiral galaxy in theconstellationUrsa Major. It was discovered byWilliam Herschel on 15 January 1788.[6][3] NGC 3198 is located in theLeo Spur,[3] which is part of theVirgo Supercluster,[7] and is approximately 47 million light years away.[3]
NGC 3198 was one of 18 galaxies targeted by theHubble Space Telescope (HST) Key Project on the Extragalactic Distance Scale, which aimed to calibrate various secondary distance indicators and determine theHubble constant to an accuracy of 10%. The type and orientation of NGC 3198 made it suitable for these measurements.[8] TheWide Field and Planetary Camera 2 (WFPC2) of the HST was used to measure themagnitudes of 52Cepheid variables, and the resultingdistance modulus corresponded to a distance of 14.5Mpc (47 millionlight years).[8]
Observations made with theWesterbork Synthesis Radio Telescope detected for the first time the presence ofextraplanar gas.[9] The extraplanar gas makes up approximately 15% of the totalatomic hydrogen (HI) mass of the galaxy.[9]
Twosupernovae have been observed in NGC 3198:
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Media related toNGC 3198 at Wikimedia Commons
