S/2018 J 2

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° 26^m 5.896^s / 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 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 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]

References

1. "MPEC 2022-Y68 : S/2018 J 2". Minor Planet Electronic Circulars. Minor Planet Center. 20 December 2022. Retrieved 20 December 2022.
2. "Planetary Satellite Discovery Circumstances". JPL Solar System Dynamics. NASA. Retrieved 20 December 2022.
3. Sheppard, Scott S. "Moons of Jupiter". Earth & Planets Laboratory. Carnegie Institution for Science. Retrieved 20 December 2022.