S/2021 J 4

S/2021 J 4
Discovery[1]
Discovered byScott S. Sheppard
Discovery siteLas Campanas Obs.
Discovery date14 August 2021
Orbital characteristics[1][2]
Epoch 25 February 2023 (JD 2460000.5)
Observation arc1.17 yr (427 d)
0.1533891 AU (22,946,680 km)
Eccentricity0.1585459
–1.94 yr (–710.13 days)
102.76481°
0° 30m 25.027s / day
Inclination164.54657° (to ecliptic)
218.88401°
217.30730°
Satellite ofJupiter
GroupCarme group
Physical characteristics
≈1 km[3]
24.0[3]
17.4[1]

S/2021 J 4 is a small outer natural satellite of Jupiter discovered by Scott S. Sheppard on 14 August 2021, using the 6.5-meter Magellan-Baade Telescope at Las Campanas Observatory, Chile. It was announced by the Minor Planet Center on 19 January 2023, after observations were collected over a long enough time span to confirm the satellite's orbit.[1]

S/2021 J 4 is part of the Carme group, a tight cluster of retrograde irregular moons of Jupiter that follow similar orbits to Carme at semi-major axes between 22–24 million km (14–15 million mi), orbital eccentricities between 0.2 and 0.3, and inclinations between 163 and 166°.[3] It has a diameter of about 1 km (0.62 mi) for an absolute magnitude of 17.4, making it one of Jupiter's smallest known moons.[3]

  1. ^ a b c d Cite error: The named reference MPEC-2023-B40 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference jplsats-disc was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference SheppardMoons was invoked but never defined (see the help page).