Jupiter moon Callicore’s orbit refined by occultation observations

On 15 December 2025 an occultation of a background star by Callicore, an irregular moon of Jupiter, was recorded by 13 telescopes worldwide. Three instruments from the Valle d'Aosta Observatory in Italy captured the event, reducing the uncertainty on Callicore’s position from more than 1 500 km to about 260 km.

The improved orbital data supports planning for a close fly‑by by ESA’s Jupiter Icy Moons Explorer (JUICE) mission, which could encounter Callicore around 2031. The campaign was coordinated by Juan Luis Rizos of the Institute of Astrophysics of Andalusia, with additional analysis from ESA scientists such as Pasquale Palumbo of INAF.

These results tighten the trajectory predictions needed for the JUICE spacecraft and enhance knowledge of the moon’s shape and dynamics.