2018 EC4

2018 EC₄ is a small asteroid and Mars trojan orbiting near the L₅ point of Mars (60 degrees behind Mars on its orbit).^[2]

2018 EC₄ was first observed on 10 March 2018 by the Mt. Lemmon Survey, but it had already been imaged (but not identified as an asteroid) by the Pan-STARRS 1 telescope system at Haleakala 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 as Mars-crosser by the Minor 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 stable L₅ Mars trojan with a libration period of 1250 yr and an amplitude of 17°.^[2] These values are similar to those of 5261 Eureka and related objects and it may be a member of the so-called Eureka family.^{[citation needed]}

L₄ (leading):

• (121514) 1999 UJ7 †

L₅ (trailing):

• 5261 Eureka (1990 MB) †
• (101429) 1998 VF31 †
• (311999) 2007 NS2 †
• (385250) 2001 DH47
• 2009 SE
• 2011 SC191
• 2011 SL25
• 2011 SP189
• 2011 UB256
• 2011 UN63
• 2016 CP31
• 2018 EC4
• 2018 FC4

• 2020 VT1

• Three new stable L5 Mars Trojans de la Fuente Marcos, C., de la Fuente Marcos, R. 2013, Monthly Notices of the Royal Astronomical Society: Letters, Vol. 432, Issue 1, pp. 31–35.
• Orbital clustering of Martian Trojans: An asteroid family in the inner solar system? Christou, A. A. 2013, Icarus, Vol. 224, Issue 1, pp. 144–153.

• 2018 EC₄ data at MPC.
• 2018 EC4 at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 2018 EC4 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters