Jupiter Trojan (617) Patroclus / Menoetius occults an 11.9 Vmag star across Europe on 2026 Jan 4^st

Several fortunate coincidences are coming together on 2026 January 4. First, a relative bright star will be occulted by both components of the Trojan (617) Patroclus / Menoetius across Europe. Second, both occultations last quite a long time. This is because, on this day, the binary Trojan will be almost at its stationary point after its retrograde motion and will therefore “creep” across the celestial plane. Patroclus has a diameter of approximately 131 kilometres, while Menoetius is slightly smaller at 116 kilometres. Both objects are less than 700 kilometres apart and orbit a common centre of gravity.

A Target for Lucy

NASA's Lucy spacecraft is on its way to the Jupiter Trojans at Lagrange point L4 since October 2021. Once the probe has explored four Trojans there, it will return to Earth for a swing-by maneuver and then set off for Lagrange point L5 to explore (617) Patroclus and Menoetius in 2033.

The following path predictions were made by Josselin Desmars (IPSA, LTE (IMCCE), Observatoire de Paris) on 2025 Dec 15 according to an orbital solution computed by Ziyu Liu (Observatoire de Paris). The following maps are screenshots from the predictions of the Lucky Star project.

Menoetius

The double occultation event starts with Menoetius. Menoetius will occult UCAC4 541-004490 in the constellation Aries for a maximum of 29 seconds in Algeria. Then shadow reaches continental Europe in the south of France and Italy at ~22:42 UT. The shadow path continues to Switzerland and Austria, crosses Germany from the south to the east with Berlin close to the centre line. Talhttps://lesia.obspm.fr/lucky-star/occ.php?p=173020lin in Estonia and Helsinki in Finland are inside the predicted path.
Details:  https://lesia.obspm.fr/lucky-star/occ.php?p=173020

Patroclus


The shadow of (617) Patroclus lies east of Menoetius’ path. It will pass eastern Sicilia at ~ 22:41 UT. The shadow reaches continental Europe in the south of Italy near Catanzaro. It will cross Montenegro, Croatia, Bosnia-Herzegovina and Serbia with Belgrade inside the path.While the eastern part of the path covers Romania, the western part of the path will cross Hungary, Slovakia and the southeast of Poland before reaching Ukraine. During this occultation, observers will be rewarded with an even longer maximum duration of 34 seconds.
Details:  https://lesia.obspm.fr/lucky-star/occ.php?p=173019