|Discovered by||R. M. West|
|Discovery site||La Silla Obs.|
|Discovery date||24 October 1976|
|MPC designation||(2148) Epeios|
|Pronunciation||// · ə-PEE-əs|
|Jupiter trojan |
Greek  · background 
|Orbital characteristics |
|Epoch 23 March 2018 (JD 2458200.5)|
|Uncertainty parameter 0|
|Observation arc||40.69 yr (14,862 d)|
|11.91 yr (4,350 d)|
|0° 4m 58.08s / day|
|Jupiter MOID||0.0308 AU|
2148 Epeios (// ə-PEE-əs), provisional designation 1976 UW, is a mid-sized Jupiter trojan from the Greek camp, approximately 38 kilometers (24 miles) in diameter. It was discovered on 24 October 1976, by Danish astronomer Richard Martin West at ESO's La Silla Observatory in northern Chile. The dark Jovian asteroid is the principal body of the proposed Epeios family and was named after Epeius from Greek mythology.
Orbit and classification
Epeios is a Jupiter trojan in a 1:1 orbital resonance with Jupiter. It is located in the leading Greek camp at the Gas Giant's L4 Lagrangian point, 60° ahead on its orbit . It orbits the Sun at a distance of 4.9–5.5 AU once every 11 years and 11 months (4,350 days; semi-major axis of 5.22 AU). Its orbit has an eccentricity of 0.06 and an inclination of 9° with respect to the ecliptic. The body's observation arc begins with its official discovery observation at La Silla in October 1976.
Fernando Roig and Ricardo Gil-Hutton identified Epeios as the principal body of a small Jovian asteroid family, using the hierarchical clustering method (HCM), which looks for groupings of neighboring asteroids based on the smallest distances between them in the proper orbital element space. According to the astronomers, the Epeios family belongs to the larger Menelaus clan, an aggregation of Jupiter trojans which is composed of several families, similar to the Flora family in the inner asteroid belt.:9,10
However this family is not included in David Nesvorný's HCM-analysis from 2014. Instead, Epeios is listed as a non-family asteroid of the Jovian background population on the Asteroids Dynamic Site (AstDyS) which based on another analysis by Milani and Knežević.
This minor planet was named from Greek mythology after the Greek warrior Epeius, leader of the contingent from Phocis during the Trojan War. Epeius also built the wooden Trojan Horse. He then chose the other 29 soldiers who would accompany him inside. The official naming citation was published by the Minor Planet Center before November 1977 (M.P.C. 4788).
Diameter and albedo
- "2148 Epeios (1976 UW)". Minor Planet Center. Retrieved 20 June 2018.
- "JPL Small-Body Database Browser: 2148 Epeios (1976 UW)" (2017-07-03 last obs.). Jet Propulsion Laboratory. Retrieved 20 June 2018.
- "List of Jupiter Trojans". Minor Planet Center. 1 June 2018. Retrieved 20 June 2018.
- "Asteroid (2148) Epeios – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 20 June 2018.
- Grav, T.; Mainzer, A. K.; Bauer, J. M.; Masiero, J. R.; Nugent, C. R. (November 2012). "WISE/NEOWISE Observations of the Jovian Trojan Population: Taxonomy". The Astrophysical Journal. 759 (1): 10. arXiv:1209.1549. Bibcode:2012ApJ...759...49G. doi:10.1088/0004-637X/759/1/49. Retrieved 20 June 2018. (online catalog)
- Roig, F.; Ribeiro, A. O.; Gil-Hutton, R. (June 2008). "Taxonomy of asteroid families among the Jupiter Trojans: comparison between spectroscopic data and the Sloan Digital Sky Survey colors" (PDF). Astronomy and Astrophysics. 483 (3): 911–931. arXiv:0712.0046. Bibcode:2008A&A...483..911R. doi:10.1051/0004-6361:20079177. Retrieved 29 June 2018.
- Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families" (PDF). Asteroids IV: 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. Retrieved 29 June 2017.
- "Asteroid 2148 Epeios". Small Bodies Data Ferret. Retrieved 20 June 2018.
- "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 20 June 2018.
- Dictionary of Minor Planet Names, Google books
- Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
- Asteroid 2148 Epeios at the Small Bodies Data Ferret
- 2148 Epeios at AstDyS-2, Asteroids—Dynamic Site
- 2148 Epeios at the JPL Small-Body Database