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Discovery
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| Discovered by | C. H. F. Peters |
| Discovery date | August 16, 1885 |
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Designations
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| Alternate name(s) | 1973 PB |
| Minor planet category |
Main belt |
| Epoch 30 January 2005 (JD 2453400.5) | |
| Aphelion | 432.742 Gm (2.893 AU) |
| Perihelion | 279.103 Gm (1.866 AU) |
| Semi-major axis | 355.922 Gm (2.379 AU) |
| Eccentricity | 0.216 |
| Orbital period | 1340.402 d (3.67 a) |
| Average orbital speed | 19.31 km/s |
| Mean anomaly | 175.357° |
| Inclination | 9.629° |
| Longitude of ascending node | 334.851° |
| Argument of perihelion | 41.91° |
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Physical characteristics
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| Dimensions | 35.0 km |
| Mass | unknown |
| Mean density | unknown |
| Equatorial surface gravity | unknown |
| Escape velocity | unknown |
| Rotation period | 85.24 h |
| Albedo | 0.043 |
| Temperature | unknown |
| Spectral type | unknown |
| Absolute magnitude (H) | 11.33 |
249 Ilse is a Main belt asteroid. It has an unusually slow rotation period, about 3.5 days.
It was discovered by C. H. F. Peters on August 16, 1885 in Clinton, New York and was named after Ilse, a legendary German princess.
Due to the long rotation period, a possible asteroidal satellite of Ilse was proposed by R. P. Binzel in 1987. No evidence of it has been provided, however.[1]
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