# 2148 Epeios

2148 Epeios /ɪˈpiːɒs/ 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 L$_4$ Lagrangian point, 60° ahead on its orbit (see Trojans in astronomy). 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.

### Epeios family

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.

## Naming

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 on 1 July 1979 (M.P.C. 4788).

## Physical characteristics
### Rotation period

As of 2018, no rotational lightcurve of Epeios has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.

### Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Epeios measures 37.98 kilometers in diameter and its surface has an albedo of 0.064.
Largest Jupiter Trojans by survey$^{(A)}$ (mean-diameter in kilometers; YoD: Year of Discovery) :
| Designation | H | WISE | IRAS | Akari | Ln | RP | V–I | YoD | Ref |
| 624 Hektor | 7.2 | 225 | 233 | 230.99 | L4 | 6.92 | 0.930 | 1907 | list |
| 617 Patroclus | 8.19 | 140.362 | 140.92 | 140.85 | L5 | 102.80 | 0.830 | 1906 | list |
| 911 Agamemnon | 7.89 | 131.038 | 166.66 | 185.30 | L4 | 6.59 | 0.980 | 1919 | list |
| 588 Achilles | 8.67 | 130.099 | 135.47 | 133.22 | L4 | 7.31 | 0.940 | 1906 | list |
| 3451 Mentor | 8.4 | 126.288 | 116.30 | 117.91 | L5 | 7.70 | 0.770 | 1984 | list |
| 3317 Paris | 8.3 | 118.790 | 116.26 | 120.45 | L5 | 7.09 | 0.950 | 1984 | list |
| 1867 Deiphobus | 8.3 | 118.220 | 122.67 | 131.31 | L5 | 58.66 | 0.930 | 1971 | list |
| 1172 Äneas | 8.33 | 118.020 | 142.82 | 148.66 | L5 | 8.71 | 0.950 | 1930 | list |
| 1437 Diomedes | 8.3 | 117.786 | 164.31 | 172.60 | L4 | 24.49 | 0.810 | 1937 | list |
| 1143 Odysseus | 7.93 | 114.624 | 125.64 | 130.81 | L4 | 10.11 | 0.860 | 1930 | list |
| 2241 Alcathous | 8.64 | 113.682 | 114.63 | 118.87 | L5 | 7.69 | 0.940 | 1979 | list |
| 659 Nestor | 8.99 | 112.320 | 108.87 | 107.06 | L4 | 15.98 | 0.790 | 1908 | list |
| 3793 Leonteus | 8.7 | 112.046 | 86.26 | 87.58 | L4 | 5.62 | 0.780 | 1985 | list |
| 3063 Makhaon | 8.4 | 111.655 | 116.14 | 114.34 | L4 | 8.64 | 0.830 | 1983 | list |
| 1583 Antilochus | 8.6 | 108.842 | 101.62 | 111.69 | L4 | 31.54 | 0.950 | 1950 | list |
| 884 Priamus | 8.81 | 101.093 | 96.29 | 119.99 | L5 | 6.86 | 0.900 | 1917 | list |
| 1208 Troilus | 8.99 | 100.477 | 103.34 | 111.36 | L5 | 56.17 | 0.740 | 1931 | list |
| 1173 Anchises | 8.89 | 99.549 | 126.27 | 120.49 | L5 | 11.60 | 0.780 | 1930 | list |
| 2207 Antenor | 8.89 | 97.658 | 85.11 | 91.32 | L5 | 7.97 | 0.950 | 1977 | list |
| 2363 Cebriones | 9.11 | 95.976 | 81.84 | 84.61 | L5 | 20.05 | 0.910 | 1977 | list |
| 4063 Euforbo | 8.7 | 95.619 | 102.46 | 106.38 | L4 | 8.85 | 0.950 | 1989 | list |
| 2357 Phereclos | 8.94 | 94.625 | 94.90 | 98.45 | L5 | 14.39 | 0.960 | 1981 | list |
| 4709 Ennomos | 8.5 | 91.433 | 80.85 | 80.03 | L5 | 12.28 | 0.690 | 1988 | list |
| 2797 Teucer | 8.7 | 89.430 | 111.14 | 113.99 | L4 | 10.15 | 0.920 | 1981 | list |
| 2920 Automedon | 8.8 | 88.574 | 111.01 | 113.11 | L4 | 10.21 | 0.950 | 1981 | list |
| 15436 Dexius | 9.1 | 87.646 | 85.71 | 78.63 | L4 | 8.97 | 0.870 | 1998 | list |
| 3596 Meriones | 9.2 | 87.380 | 75.09 | 73.28 | L4 | 12.96 | 0.830 | 1985 | list |
| 2893 Peiroos | 9.23 | 86.884 | 87.46 | 86.76 | L5 | 8.96 | 0.950 | 1975 | list |
| 4086 Podalirius | 9.1 | 85.495 | 86.89 | 85.98 | L4 | 10.43 | 0.870 | 1985 | list |
| 4060 Deipylos | 9.3 | 84.043 | 79.21 | 86.79 | L4 | 9.30 | 0.760 | 1987 | list |
| 1404 Ajax | 9.3 | 83.990 | 81.69 | 96.34 | L4 | 29.38 | 0.960 | 1936 | list |
| 4348 Poulydamas | 9.5 | 82.032 | 70.08 | 87.51 | L5 | 9.91 | 0.840 | 1988 | list |
| 5144 Achates | 9.0 | 80.958 | 91.91 | 89.85 | L5 | 5.96 | 0.920 | 1991 | list |
| 4833 Meges | 8.9 | 80.165 | 87.33 | 89.39 | L4 | 14.25 | 0.940 | 1989 | list |
| 2223 Sarpedon | 9.41 | 77.480 | 94.63 | 108.21 | L5 | 22.74 | 0.880 | 1977 | list |
| 4489 Dracius | 9.0 | 76.595 | 92.93 | 95.02 | L4 | 12.58 | 0.950 | 1988 | list |
| 2260 Neoptolemus | 9.31 | 76.435 | 71.65 | 81.28 | L4 | 8.18 | 0.950 | 1975 | list |
| 5254 Ulysses | 9.2 | 76.147 | 78.34 | 80.00 | L4 | 28.72 | 0.970 | 1986 | list |
| 3708 Socus | 9.3 | 75.661 | 79.59 | 76.75 | L5 | 6.55 | 0.980 | 1974 | list |
| 2674 Pandarus | 9.1 | 74.267 | 98.10 | 101.72 | L5 | 8.48 | 1.000 | 1982 | list |
| 3564 Talthybius | 9.4 | 73.730 | 68.92 | 74.11 | L4 | 40.59 | 0.900 | 1985 | list |
| 4834 Thoas | 9.1 | 72.331 | 86.82 | 96.21 | L4 | 18.19 | 0.950 | 1989 | list |
| 7641 Cteatus | 9.4 | 71.839 | 68.97 | 75.28 | L4 | 27.77 | 0.980 | 1986 | list |
| 3540 Protesilaos | 9.3 | 70.225 | 76.84 | 87.66 | L4 | 8.95 | 0.940 | 1973 | list |
| 11395 Iphinous | 9.8 | 68.977 | 64.71 | 67.78 | L4 | 17.38 | – | 1998 | list |
| 4035 Thestor | 9.6 | 68.733 | 68.23 | 66.99 | L4 | 13.47 | 0.970 | 1986 | list |
| 5264 Telephus | 9.4 | 68.472 | 73.26 | 81.38 | L4 | 9.53 | 0.970 | 1991 | list |
| 1868 Thersites | 9.5 | 68.163 | 70.08 | 78.89 | L4 | 10.48 | 0.960 | 1960 | list |
| 9799 Thronium | 9.6 | 68.033 | 64.87 | 72.42 | L4 | 21.52 | 0.910 | 1996 | list |
| 4068 Menestheus | 9.5 | 67.625 | 62.37 | 68.46 | L4 | 14.40 | 0.950 | 1973 | list |
| 23135 Pheidas | 9.9 | 66.230 | 58.29 | 68.50 | L4 | 8.69 | 0.860 | 2000 | list |
| 2456 Palamedes | 9.3 | 65.916 | 91.66 | 99.60 | L4 | 7.24 | 0.920 | 1966 | list |
| 3709 Polypoites | 9.1 | 65.297 | 99.09 | 85.23 | L4 | 10.04 | 1.000 | 1985 | list |
| 1749 Telamon | 9.5 | 64.898 | 81.06 | 69.14 | L4 | 16.98 | 0.970 | 1949 | list |
| 3548 Eurybates | 9.6 | 63.885 | 72.14 | 68.40 | L4 | 8.71 | 0.730 | 1973 | list |
| 4543 Phoinix | 9.7 | 63.836 | 62.79 | 69.54 | L4 | 38.87 | 1.200 | 1989 | list |
| 12444 Prothoon | 9.8 | 63.835 | 64.31 | 62.41 | L5 | 15.82 | – | 1996 | list |
| 4836 Medon | 9.5 | 63.277 | 67.73 | 78.70 | L4 | 9.82 | 0.920 | 1989 | list |
| 16070 Charops | 9.7 | 63.191 | 64.13 | 68.98 | L5 | 20.24 | 0.960 | 1999 | list |
| 15440 Eioneus | 9.6 | 62.519 | 66.48 | 71.88 | L4 | 21.43 | 0.970 | 1998 | list |
| 4715 Medesicaste | 9.7 | 62.097 | 63.91 | 65.93 | L5 | 8.81 | 0.850 | 1989 | list |
| 34746 Thoon | 9.8 | 61.684 | 60.51 | 63.63 | L5 | 19.63 | 0.950 | 2001 | list |
| 38050 Bias | 9.8 | 61.603 | 61.04 | 50.44 | L4 | 18.85 | 0.990 | 1998 | list |
| 5130 Ilioneus | 9.7 | 60.711 | 59.40 | 52.49 | L5 | 14.77 | 0.960 | 1989 | list |
| 5027 Androgeos | 9.6 | 59.786 | 57.86 | n.a. | L4 | 11.38 | 0.910 | 1988 | list |
| 6090 Aulis | 9.4 | 59.568 | 74.53 | 81.92 | L4 | 18.48 | 0.980 | 1989 | list |
| 5648 Axius | 9.7 | 59.295 | 63.91 | n.a. | L5 | 37.56 | 0.900 | 1990 | list |
| 7119 Hiera | 9.7 | 59.150 | 76.40 | 77.29 | L4 | 400 | 0.950 | 1989 | list |
| 4805 Asteropaios | 10.0 | 57.647 | 53.16 | 43.44 | L5 | 12.37 | – | 1990 | list |
| 16974 Iphthime | 9.8 | 57.341 | 55.43 | 57.15 | L4 | 78.9 | 0.960 | 1998 | list |
| 4867 Polites | 9.8 | 57.251 | 58.29 | 64.29 | L5 | 11.24 | 1.010 | 1989 | list |
| 2895 Memnon | 10.0 | 56.706 | 55.67 | n.a. | L5 | 7.50 | 0.710 | 1981 | list |
| 4708 Polydoros | 9.9 | 54.964 | 55.67 | n.a. | L5 | 7.52 | 0.960 | 1988 | list |
| (21601) 1998 XO89 | 10.0 | 54.909 | 55.67 | 56.08 | L4 | 12.65 | 0.970 | 1998 | list |
| 12929 Periboea | 9.9 | 54.077 | 61.04 | 55.34 | L5 | 9.27 | 0.880 | 1999 | list |
| 17492 Hippasos | 10.0 | 53.975 | 55.67 | n.a. | L5 | 17.75 | – | 1991 | list |
| 5652 Amphimachus | 10.1 | 53.921 | 53.16 | 52.48 | L4 | 8.37 | 1.050 | 1992 | list |
| 2759 Idomeneus | 9.9 | 53.676 | 61.01 | 52.55 | L4 | 32.38 | 0.910 | 1980 | list |
| 5258 Rhoeo | 10.2 | 53.275 | 50.77 | n.a. | L4 | 19.85 | 1.010 | 1989 | list |
| (12126) 1999 RM11 | 10.1 | 53.202 | n.a. | n.a. | L5 | n.a. | ? | 1999 | list |
| (15502) 1999 NV27 | 10.0 | 53.100 | 55.67 | 50.86 | L5 | 15.13 | 0.875 | 1999 | list |
| 4754 Panthoos | 10.0 | 53.025 | 53.15 | 56.96 | L5 | 27.68 | – | 1977 | list |
| 4832 Palinurus | 10.0 | 52.058 | 53.16 | n.a. | L5 | 5.32 | 1.000 | 1988 | list |
| 5126 Achaemenides | 10.5 | 51.922 | 44.22 | 48.57 | L4 | 53.02 | – | 1989 | list |
| 3240 Laocoon | 10.2 | 51.695 | 50.77 | n.a. | L5 | 11.31 | 0.880 | 1978 | list |
| 4902 Thessandrus | 9.8 | 51.263 | 61.04 | 71.79 | L4 | 738 | 0.960 | 1989 | list |
| 11552 Boucolion | 10.1 | 51.136 | 53.16 | 53.91 | L5 | 32.44 | – | 1993 | list |
| (20729) 1999 XS143 | 10.4 | 50.961 | 46.30 | n.a. | L4 | 5.72 | 1.000 | 1999 | list |
| 6545 Leitus | 10.1 | 50.951 | 53.16 | n.a. | L4 | 16.26 | 0.910 | 1986 | list |
| 4792 Lykaon | 10.1 | 50.870 | 53.16 | n.a. | L5 | 40.09 | 0.960 | 1988 | list |
| 21900 Orus | 10.0 | 50.810 | 55.67 | 53.87 | L4 | 13.45 | 0.950 | 1999 | list |
| 1873 Agenor | 10.1 | 50.799 | 53.76 | 54.38 | L5 | 20.60 | – | 1971 | list |
| 5028 Halaesus | 10.2 | 50.770 | 50.77 | n.a. | L4 | 24.94 | 0.900 | 1988 | list |
| 2146 Stentor | 9.9 | 50.755 | 58.29 | n.a. | L4 | 16.40 | – | 1976 | list |
| 4722 Agelaos | 10.0 | 50.378 | 53.16 | 59.47 | L5 | 18.44 | 0.910 | 1977 | list |
| 5284 Orsilocus | 10.1 | 50.159 | 53.16 | n.a. | L4 | 10.31 | 0.970 | 1989 | list |
| 11509 Thersilochos | 10.1 | 49.960 | 53.16 | 56.23 | L5 | 17.37 | – | 1990 | list |
| 5285 Krethon | 10.1 | 49.606 | 58.53 | 52.61 | L4 | 12.04 | 1.090 | 1989 | list |
| 4791 Iphidamas | 10.1 | 49.528 | 57.85 | 59.96 | L5 | 9.70 | 1.030 | 1988 | list |
| 9023 Mnesthus | 10.1 | 49.151 | 50.77 | 60.80 | L5 | 30.66 | – | 1988 | list |
| 5283 Pyrrhus | 9.7 | 48.356 | 64.58 | 69.93 | L4 | 7.32 | 0.950 | 1989 | list |
| 4946 Askalaphus | 10.2 | 48.209 | 52.71 | 66.10 | L4 | 22.73 | 0.940 | 1988 | list |
| (22149) 2000 WD49 | 10.2 | 48.190 | 50.77 | 50.37 | L4 | 7.84 | 1.090 | 2000 | list |
| (32496) 2000 WX182 | 10.2 | 48.017 | 50.77 | 51.63 | L5 | 23.34 | 0.950 | 2000 | list |
| 5120 Bitias | 10.2 | 47.987 | 50.77 | n.a. | L5 | 15.21 | 0.780 | 1988 | list |
| 12714 Alkimos | 10.1 | 47.819 | 61.04 | 54.62 | L4 | 28.48 | – | 1991 | list |
| 7352 Hypsenor | 9.9 | 47.731 | 55.67 | 47.07 | L5 | 648 | 0.850 | 1994 | list |
| 1870 Glaukos | 10.6 | 47.649 | 42.23 | n.a. | L5 | 5.99 | — | 1971 | list |
| 4138 Kalchas | 10.1 | 46.462 | 53.16 | 61.04 | L4 | 29.2 | 0.810 | 1973 | list |
| (23958) 1998 VD30 | 10.2 | 46.001 | 50.77 | 47.91 | L4 | 562 | 0.990 | 1998 | list |
| 4828 Misenus | 10.4 | 45.954 | 46.30 | 43.22 | L5 | 12.87 | 0.920 | 1988 | list |
| 4057 Demophon | 10.1 | 45.683 | 53.16 | n.a. | L4 | 29.82 | 1.060 | 1985 | list |
| 4501 Eurypylos | 10.4 | 45.524 | 46.30 | n.a. | L4 | 6.05 | – | 1989 | list |
| 4007 Euryalos | 10.3 | 45.515 | 48.48 | 53.89 | L4 | 6.39 | – | 1973 | list |
| 5259 Epeigeus | 10.3 | 44.741 | 42.59 | 44.42 | L4 | 18.42 | – | 1989 | list |
| 30705 Idaios | 10.4 | 44.546 | 46.30 | n.a. | L5 | 15.74 | – | 1977 | list |
| 16560 Daitor | 10.7 | 43.861 | 51.42 | 43.38 | L5 | – | – | 1991 | list |
| (15977) 1998 MA11 | 10.4 | 43.530 | 46.30 | 51.53 | L5 | 250 | 0.906 | 1998 | list |
| 7543 Prylis | 10.6 | 42.893 | 42.23 | n.a. | L4 | 17.80 | – | 1973 | list |
| 4827 Dares | 10.5 | 42.770 | 44.22 | n.a. | L5 | 19.00 | – | 1988 | list |
| 1647 Menelaus | 10.5 | 42.716 | 44.22 | n.a. | L4 | 17.74 | 0.866 | 1957 | list |
| $^{(A)}$ Used sources: WISE/NEOWISE catalog (NEOWISE_DIAM_V1 PDS, Grav, 2012); IRAS data (SIMPS v.6 catalog); and Akari catalog (Usui, 2011); RP: rotation period and V–I (color index) taken from the LCDB Note: missing data was completed with figures from the JPL SBDB (query) and from the LCDB (query form) for the WISE/NEOWISE and SIMPS catalogs, respectively. These figures are given in italics. Also, listing is incomplete above #100. ||||||||||