| Discovery[1] | |
|---|---|
| Discovered by | T. Hioki N. Kawasato |
| Discovery site | Okutama Obs. |
| Discovery date | 8 October 1989 |
| Designations | |
| (9942)1989 TM1 | |
| 1989 TM1 | |
| main-belt[1][2] · (middle)[3] background | |
| Orbital characteristics[2] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 26.64 yr (9,732 days) |
| Aphelion | 3.0287AU |
| Perihelion | 2.1619 AU |
| 2.5953 AU | |
| Eccentricity | 0.1670 |
| 4.18yr (1,527 days) | |
| 217.94° | |
| 0° 14m 8.52s / day | |
| Inclination | 9.9393° |
| 21.747° | |
| 38.492° | |
| Physical characteristics | |
| 4.12±0.45 km[4] 4.73 km(calculated)[3] | |
| 3.0706±0.0004 h[5] | |
| 0.20(assumed)[3] 0.454±0.106[4] | |
| S(assumed)[3] | |
| 13.40[4] · 13.541[5] 13.6[2] · 13.99[3] | |
(9942) 1989 TM1 (provisional designation1989 TM1) is a backgroundasteroid from the central region of theasteroid belt, approximately 4.5 kilometers (2.8 miles) in diameter. It was discovered on 8 October 1989, by Japanese astronomersNobuhiro Kawasato andTsutomu Hioki at the Okutama Observatory (877) in Japan.[1] The asteroid has a tentativerotation period of 3.1 hours.[3]
The assumed stonyS-type is a non-family asteroid from the main belt'sbackground population. It orbits the Sun in thecentral main-belt at a distance of 2.2–3.0 AU once every 4 years and 2 months (1,527 days;semi-major axis of 2.6 AU). Its orbit has aneccentricity of 0.17 and aninclination of 10° with respect to theecliptic.[2]
Its first observation was aprecovery taken at thePalomar Observatory on 30 September 1989, extending the asteroid'sobservation arc by just 9 days prior to its official discovery observation.[1]
Thisminor planet wasnumbered by theMinor Planet Center on 2 February 1999.[6] As of 2018, it has not beennamed.[1]
The asteroid was predicted to cross the focal plane array of theInfrared Astronomical Satellite (IRAS). However, it was missed on each of its seven planned observation and was never detected. According to the "missed predictions file" of the supplemental IRAS minor planet survey (SIMPS), the body was expected to have a diameter of 13.5 kilometers and an absolute magnitude of 13.20.[7]
Based on an absolute magnitude of 13.99, and an assumed standardalbedo for stony asteroids of 0.20, theCollaborative Asteroid Lightcurve Link calculated a much smaller diameter of 4.7 kilometers,[3] which agrees with a diameter of 4.1 kilometers, found by NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission.[4]
In October 2010, a rotationallightcurve for this asteroid was obtained fromphotometric observations at thePalomar Transient Factory in California. It rendered a tentativerotation period of3.0706±0.0004 hours with a brightness variation of 0.08 inmagnitude (U=1).[5]
