2018 FC4 was first observed on 21 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 the previous night.[3] Its orbit is characterized by very low eccentricity (0.017), moderate inclination (22.1°) 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 reasonably well determined as it is currently (January 2021) based on 35 observations with a data-arc span of 790 days.[1]2018 FC4 has an absolute magnitude of 21.3 which gives a characteristic diameter of 200 m.[1]
Mars trojan and orbital evolution
Recent calculations indicate that it is a stable L5Mars trojan with a libration period of 1300 yr and an amplitude of 20°.[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.
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.
