| Discovery | |
|---|---|
| Discovered by | Mt. Lemmon Survey |
| Discovery date | 10 March 2018 |
| Designations | |
| 2018 EC4 | |
Martian L5 | |
| Orbital characteristics[1] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 3131 days (8.57 yr) |
| Aphelion | 1.61579336 AU (241.719246 Gm) |
| Perihelion | 1.43135923 AU (214.128293 Gm) |
| 1.52357630 AU (227.923770 Gm) | |
| Eccentricity | 0.06052671 |
| 1.88yr (686.90193d) | |
| 203.4934° | |
| 0° 31m 26.732s /day | |
| Inclination | 21.835796° |
| 47.371564° | |
| 344.1754° | |
| Earth MOID | 0.443437 AU (66.3372 Gm) |
| Jupiter MOID | 3.54199 AU (529.874 Gm) |
| Physical characteristics | |
| Dimensions | 300 m |
| 0.5-0.05 (assumed) | |
| 20.1 | |
2018 EC4 is a smallasteroid andMars trojan orbiting near theL5 point ofMars (60 degrees behind Mars on its orbit).[2]
2018 EC4 was first observed on 10 March 2018 by theMt. Lemmon Survey, but it had already been imaged (but not identified as an asteroid) by thePan-STARRS 1 telescope system atHaleakala on 29 October 2011.[3] Its orbit is characterized by low eccentricity (0.061), moderate inclination (21.8°) and a semi-major axis of 1.52 AU.[3] Upon discovery, it was classified asMars-crosser by theMinor Planet Center. Its orbit is well determined as it is currently (January 2021) based on 70 observations with a data-arc span of 3,131 days.[1]2018 EC4 has an absolute magnitude of 20.1 which gives a characteristic diameter of 300 m.[1]
Recent calculations indicate that it is a stableL5Mars trojan with a libration period of 1250 yr and an amplitude of 17°.[2] These values are similar to those of5261 Eureka and related objects and it may be a member of the so-called Eureka family.[citation needed]
L4 (leading):
L5 (trailing):
