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Discovery
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| Discovered by | Guillaume Bigourdan |
| Discovery date | March 24, 1894 |
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Designations
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| Named after | Alma River |
| Alternate name(s) | 1894 BC; 1930 QW; 1950 BV; 1950 CH; 1953 YB; 1963 DF |
| Minor planet category |
Main belt (Eunomia family) |
| Epoch 30 January 2005 (JD 2453400.5) | |
| Aphelion | 448.268 Gm (2.996 AU) |
| Perihelion | 345.512 Gm (2.31 AU) |
| Semi-major axis | 396.89 Gm (2.653 AU) |
| Eccentricity | 0.129 |
| Orbital period | 1578.364 d (4.32 a) |
| Average orbital speed | 18.21 km/s |
| Mean anomaly | 258.381° |
| Inclination | 12.144° |
| Longitude of ascending node | 305.342° |
| Argument of perihelion | 190.074° |
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Physical characteristics
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| Dimensions | 24 km[1] |
| Mass | ~2×1016 kg (estimate) |
| Mean density | ~2.7 g/cm³ (estimate)[3] |
| Equatorial surface gravity | ~0.009 m/s² (estimate) |
| Escape velocity | ~0.015 km/s (estimate) |
| Rotation period | 0.156 d [2] |
| Albedo | 0.219 |
| Temperature | ~165 K max: 250 K (-23 °C) |
| Spectral type | S-type asteroid |
| Absolute magnitude (H) | 10.39 |
390 Alma is a typical medium-sized Eunomian asteroid. It was Guillaume Bigourdan's only asteroid discovery. He discovered it on March 24, 1894 in Paris.
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