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Discovery
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| Discovered by | A. Marth |
| Discovery date | March 1, 1854 |
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Designations
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| Named after | Amphitrite |
| Alternate name(s) | A899 NG |
| Minor planet category |
Main belt |
| Epoch June 14, 2006 (JD 2453900.5) | |
| Aphelion | 409.809 Gm (2.739 AU) |
| Perihelion | 354.398 Gm (2.369 AU) |
| Semi-major axis | 382.103 Gm (2.554 AU) |
| Eccentricity | 0.073 |
| Orbital period | 1491.013 d (4.08 a) |
| Average orbital speed | 18.61 km/s |
| Mean anomaly | 229.662° |
| Inclination | 6.096° |
| Longitude of ascending node | 356.501° |
| Argument of perihelion | 63.433° |
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Physical characteristics
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| Dimensions | 233×212×193 km[2] 212.2 km † |
| Mass | 1.18×1019 kg[2] |
| Mean density | 2.36 ± 0.26 g/cm³[2] |
| Equatorial surface gravity | 0.0593 m/s² |
| Escape velocity | 0.1122 km/s |
| Rotation period | 0.2246 d (5.390 h)[1][1] |
| Albedo | 0.1793 (geometric) [1][2] |
| Temperature | ~170 K |
| Spectral type | S[1] |
| Apparent magnitude | 8.65[3] to 11.46 |
| Absolute magnitude (H) | 5.85 |
| Angular diameter | 0.21" to 0.078" |
29 Amphitrite ( /ˌæmfɨˈtraɪtiː/ am-fi-try-tee; Greek: Αμφιτρίτη) is one of the largest S-type asteroids, probably third in diameter after Eunomia and Juno, although Iris and Herculina are similar in size.
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Amphitrite was discovered by Albert Marth on March 1, 1854, at the private South Villa Observatory, in Regent's Park, London. It was Marth's only asteroid discovery. Its name was chosen by George Bishop, the owner of the observatory, who named it after Amphitrite, a sea goddess in Greek mythology.[4]
Amphirite's orbit is less eccentric and inclined than those of its larger cousins; indeed, it is the most circular of any asteroid discovered up to that point. As a consequence, it never becomes as bright as Iris or Hebe, especially as it is much further from the Sun than those asteroids. It can reach magnitudes of around +8.6 at a favorable opposition, but usually is around the binocular limit of +9.5.
In 2007, James Baer and Steven R. Chesley estimated Amphitrite to have a mass of 1.9×1019 kg.[5] A more recent estimate by Baer suggests it has a mass of 1.18×1019 kg.[2]
A satellite of the asteroid is suspected to be based on lightcurve datacollected by Edward F. Tedesco.[6][7]
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