4902 Thessandrus

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4902 Thessandrus
Discovery [1]
Discovered by C. Shoemaker
Discovery site Palomar Obs.
Discovery date 9 January 1989
MPC designation 4902 Thessandrus
Pronunciation the-san'-drəs
Named after
(Greek mythology)[2]
1989 AN2 · 1985 TK3
Jupiter trojan[3][4]
(Greek camp)[5]
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc 62.29 yr (22,753 days)
Aphelion 5.4235 AU
Perihelion 4.9863 AU
5.2049 AU
Eccentricity 0.0420
11.87 yr (4,337 days)
0° 4m 58.8s / day
Inclination 9.0727°
Jupiter MOID 0.2003 AU
Jupiter Tisserand parameter 2.9730
Physical characteristics
Dimensions 51.26±0.66 km[6]
61.04 km (calculated)[4]
738±20 h[7]
0.057 (assumed)[4]
D[8] · C[4]

4902 Thessandrus (the-san'-drəs), provisionally designated 1989 AN2, is a rare-type Jupiter trojan from the Greek camp and an exceptionally slow rotator, approximately 60 kilometers in diameter. It was discovered on 9 January 1989, by American astronomer Carolyn Shoemaker at the U.S. Palomar Observatory in California.[3]

The S-type asteroid is also classified as a rare D-type asteroid by Pan-STARRS large-scale survey.[8] It orbits the Sun at a distance of 5.0–5.4 AU once every 11 years and 10 months (4,337 days). Its orbit has an eccentricity of 0.04 and an inclination of 9° with respect to the ecliptic.[1] The first precovery was taken at the discovering observatory in 1954, extending the asteroid's observation arc by 35 years prior to its discovery.[3]

In February 2013, a rotational light-curve was obtained from photometric observations by American astronomer Robert D. Stevens at the Center for Solar System Studies in California. It gave an exceptionally long rotation period of 738±20 hours with a brightness variation of 0.60 in magnitude (U=2).[7]

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, the asteroid measures 51.3 kilometers in diameter and its surface has an albedo of 0.081,[6] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057 and calculates a somewhat larger diameter of 61.0 kilometers, as the lower the albedo (reflectivity), the larger the body's diameter, at a constant absolute magnitude (brightness).[4]

The Jovian asteroid is named after Thessander (Thessandrus) from Greek mythology and Homer's Iliad. Together with 30 other Greek soldiers he hid in the Trojan horse's belly.[2] Naming citation was published on 4 June 1993 (M.P.C. 22248).[9]


  1. ^ a b c d "JPL Small-Body Database Browser: 4902 Thessandrus (1989 AN2)" (2016-06-13 last obs.). Jet Propulsion Laboratory. Retrieved 30 June 2016. 
  2. ^ a b Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (4902) Thessandrus. Springer Berlin Heidelberg. p. 423. ISBN 978-3-540-00238-3. Retrieved 30 June 2016. 
  3. ^ a b c "4902 Thessandrus (1989 AN2)". Minor Planet Center. Retrieved 30 June 2016. 
  4. ^ a b c d e f "LCDB Data for (4902) Thessandrus". Asteroid Lightcurve Database (LCDB). Retrieved 30 June 2016. 
  5. ^ "List of Jupiter Trojans". Minor Planet Center. 20 June 2016. Retrieved 30 June 2016. 
  6. ^ a b c d Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results" (PDF). The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407free to read. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 30 June 2016. 
  7. ^ a b French, Linda M.; Stephens, Robert, D.; Coley, Daniel R.; Wasserman, Lawrence H.; Vilas, Faith; La Rocca, Daniel (October 2013). "A Troop of Trojans: Photometry of 24 Jovian Trojan Asteroids". The Minor Planet Bulletin. 40 (4): 198–203. Bibcode:2013MPBu...40..198F. ISSN 1052-8091. Retrieved 30 June 2016. 
  8. ^ a b c 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:1506.00762free to read. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 30 June 2016. 
  9. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 30 June 2016. 

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