(9942) 1989 TM1

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(9942) 1989 TM1
Discovery [1]
Discovered by T. Hioki
N. Kawasato
Discovery site Okutama Obs.
Discovery date 8 October 1989
MPC designation (9942) 1989 TM1
1989 TM1
main-belt · (middle)[2]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 26.64 yr (9,732 days)
Aphelion 3.0287 AU
Perihelion 2.1619 AU
2.5953 AU
Eccentricity 0.1670
4.18 yr (1,527 days)
0° 14m 8.52s / day
Inclination 9.9393°
Physical characteristics
Dimensions 4.12±0.45 km[3]
4.73 km (calculated)[2]
3.0706±0.0004 h[4]
0.20 (assumed)[2]
13.40[3] · 13.541[4] · 13.6[1] · 13.72±0.39[5] · 13.99[2]

(9942) 1989 TM1 is a stony asteroid from the middle region of the asteroid belt, approximately 4.5 kilometers in diameter. It was discovered on 8 October 1989, by Japanese astronomers Nobuhiro Kawasato and Tsutomu Hioki at Okutama Observatory (877), Japan.[6]

Orbit and classification[edit]

Orbits of 1989 TM1 (blue) and the inner planets and Jupiter

The stony S-type asteroid orbits the Sun in the central main-belt at a distance of 2.2–3.0 AU once every 4 years and 2 months (1,527 days). Its orbit has an eccentricity of 0.17 and an inclination of 10° with respect to the ecliptic.[1]

A precovery was taken at the U.S. Palomar Observatory on 30 September 1989, extending the asteroid's observation arc by just 9 days prior to its official discovery observation.[6]

Physical characteristics[edit]

Diameter and albedo[edit]

The asteroid was predicted to cross the focal plane array of the Infrared 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 standard albedo for stony asteroids of 0.20, the Collaborative Asteroid Lightcurve Link calculated a much smaller diameter of 4.7 kilometers,[2] which agrees with a diameter of 4.1 kilometers, found by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission.[3]

Rotation period[edit]

In October 2010, a rotational light-curve for this asteroid was obtained from photometric observations at the U.S. Palomar Transient Factory, California. It rendered a tentative rotation period of 3.0706±0.0004 hours with a brightness variation of 0.08 in magnitude (U=1).[4]

Numbering and naming[edit]

This minor planet was numbered by the Minor Planet Center on 2 February 1999.[8] As of 2018, it has not been named.[6]


  1. ^ a b c d "JPL Small-Body Database Browser: 9942 (1989 TM1)" (2016-05-23 last obs.). Jet Propulsion Laboratory. Retrieved 26 May 2017. 
  2. ^ a b c d e f "LCDB Data for (9942)". Asteroid Lightcurve Database (LCDB). Retrieved 4 July 2016. 
  3. ^ a b c d Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794Freely accessible. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 4 July 2016. 
  4. ^ a b c Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal. 150 (3): 35. arXiv:1504.04041Freely accessible. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75. Retrieved 4 July 2016. 
  5. ^ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762Freely accessible. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 4 July 2016. 
  6. ^ a b c "9942 (1989 TM1)". Minor Planet Center. Retrieved 4 July 2016. 
  7. ^ Tedesco E.F.; Noah P.V.; Noah M.; Price S.D. "The supplemental IRAS minor planet survey (SIMPS) – Missed-Predictions". Retrieved 1 January 2016. 
  8. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 24 February 2018. 

External links[edit]