S/2021 J 4 is a small outer natural satelliteofJupiter discovered by Scott S. Sheppard on 14 August 2021, using the 6.5-meter Magellan-Baade TelescopeatLas 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]
| Discovery[1] | |
|---|---|
| Discovered by | Scott S. Sheppard |
| Discovery site | Las Campanas Obs. |
| Discovery date | 14 August 2021 |
| Orbital characteristics[1][2] | |
| Epoch 25 February 2023 (JD 2460000.5) | |
| Observation arc | 1.17 yr (427 d) |
| 0.1533891 AU (22,946,680 km) | |
| Eccentricity | 0.1585459 |
| –1.94 yr (–710.13 days) | |
| 102.76481° | |
| 0° 30m 25.027s / day | |
| Inclination | 164.54657° (toecliptic) |
| 218.88401° | |
| 217.30730° | |
| Satellite of | Jupiter |
| Group | Carme group |
| Physical characteristics | |
Mean diameter | ≈1 km[3] |
| 24.0[3] | |
| 17.4[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 Carmeatsemi-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]
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