S/2018 J 2

S/2018 J 2 is a small outer natural satellite of Jupiter discovered by Scott S. Sheppard on 12 May 2018, using the 4.0-meter Víctor M. Blanco Telescope at Cerro Tololo Observatory, Chile. It was announced by the Minor Planet Center four years later on 20 December 2022, after observations were collected over a long enough time span to confirm the satellite's orbit. The satellite has been found in precovery observations as early as 27 March 2003.^[1]

S/2018 J 2

Discovery[1]
Discovered by	Scott S. Sheppard
Discovery site	Cerro Tololo Obs.
Discovery date	12 May 2018
Orbital characteristics[1][2]
Epoch 9 August 2022 (JD 2459800.5)
Observation arc	19.48 yr (7,115 d)
Earliest precovery date	27 March 2003
Semi-major axis	0.0766555 AU (11,467,500 km)
Eccentricity	0.1184102
Orbital period (sidereal)	+250.88 days
Mean anomaly	99.239°
Mean motion	1° 26m 5.896s / day
Inclination	29.40421° (to ecliptic)
Longitude of ascending node	66.06734°
Argument of perihelion	342.09685°
Satellite of	Jupiter
Group	Himalia group
Physical characteristics
Mean diameter	≈3 km[3]
Albedo	0.04 (assumed)[3]
Apparent magnitude	23.3[3]
Absolute magnitude (H)	16.5[1]

S/2018 J 2 is part of the Himalia group, a tight cluster of prograde irregular moons of Jupiter that follow similar orbits to Himalia at semi-major axes between 11–12 million km (6.8–7.5 million mi) and inclinations between 26–31°.^[3] With an estimated diameter of 3 km (1.9 mi) for an absolute magnitude of 16.5, it is among the smallest known members of the Himalia group.^[3]