|Discovered by||C. Shoemaker
|Discovery site||Palomar Obs.|
|Discovery date||11 October 1985|
|MPC designation||5023 Agapenor|
|Jupiter trojan 
|Orbital characteristics |
|Epoch 31 July 2016 (JD 2457600.5)|
|Uncertainty parameter 0|
|Observation arc||30.58 yr (11,170 days)|
|11.78 yr (4,304 days)|
|0° 5m 0.96s / day|
|Jupiter MOID||0.0459 AU|
|Jupiter Tisserand parameter||2.96|
|Dimensions||±3.51 km 27.85
46.30 km (calculated)
|X  · C |
5023 Agapenor, provisional designation 1985 TG3, is an asteroid, classified as a Jupiter trojan from the Greek camp, between 25 and 50 kilometers in diameter. It was discovered by American astronomer couple Carolyn and Eugene Shoemaker at the U.S. Palomar Observatory, California, on 11 October 1985.
The asteroid is orbiting in the leading Greek camp at Jupiter's L4 Lagrangian point, 60° ahead of its orbit (see Trojans in astronomy). It orbits the Sun at a distance of 4.9–5.4 AU once every 11 years and 9 months (4,304 days). It has an eccentricity of 0.05 and an inclination of 12° with respect to the plane of the ecliptic. The first precovery was taken at the discovering observatory in September 1985, extending the asteroid's observation arc by 25 days prior to its discovery.
In September 2009, the body was observed by astronomer Stefano Mottola in a photometric survey of 80 Jupiter trojans, using the 1.2-meter reflector at Calar Alto Observatory in southeastern Spain. The obtained light-curve gave a rotation period of ±0.0017 hours with a brightness variation of 5.4020±0.01 in 0.12magnitude (U=2+).
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, the asteroid measures 27.9 kilometers in diameter and its surface has an albedo of 0.17. The body has a X-type spectrum based on a large-scale survey performed by Pan-STARRS, while the Collaborative Asteroid Lightcurve Link (CALL) classifies it as a C-type asteroid assuning a carbonaceous standard albedo of 0.057. As a consequence, CALL calculates a significantly larger diameter of 46.3 kilometers.
The minor planet was named from Greek mythology after Agapenor. He was the leader of the Greek contingent of Arcadians in the Trojan War. The minor planet 1020 Arcadia is named after this able group of warriors. Agapenor was the commander of 60 ships lend to him by Agamemnon, the king of Mycenae and leader of the Greeks in the Trojan War. 911 Agamemnon, one of the largest Jupiter trojans known to exist, is named after the commander of the Greek forces. Naming citation was published on 12 July 1995 (M.P.C. 25443).
- "JPL Small-Body Database Browser: 5023 Agapenor (1985 TG3)" (2016-04-16 last obs.). Jet Propulsion Laboratory. Retrieved May 2016.
- Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (5023) Agapenor. Springer Berlin Heidelberg. p. 432. ISBN 978-3-540-00238-3. Retrieved April 2016.
- "5023 Agapenor (1985 TG3)". Minor Planet Center. Retrieved April 2016.
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- Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved May 2016.
- Mottola, Stefano; Di Martino, Mario; Erikson, Anders; Gonano-Beurer, Maria; Carbognani, Albino; Carsenty, Uri; et al. (May 2011). "Rotational Properties of Jupiter Trojans. I. Light Curves of 80 Objects". The Astronomical Journal 141 (5): 32. Bibcode:2011AJ....141..170M. doi:10.1088/0004-6256/141/5/170. Retrieved May 2016.
- 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:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved May 2016.
- "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved May 2016.
- Asteroid Lightcurve Database (LCDB), query form (info)
- Dictionary of Minor Planet Names, Google books
- Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
- Discovery Circumstances: Numbered Minor Planets (5001)-(10000) – Minor Planet Center
- 5023 Agapenor at the JPL Small-Body Database