S/2021 J 4

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.

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 e6km, orbital eccentricities between 0.2 and 0.3, and inclinations between 163 and 166°. It has a diameter of about 1 km for an absolute magnitude of 17.4, making it one of Jupiter's smallest known moons.