We encourage interested observers to plan observations of mutual events of the Trojan binary system (617) Patroclus-Menoetius in semester 2018A. Contact times for the events and their photometric depth are the measurement objectives.

The Patroclus-Menoetius binary system undergoes a series of mutual events approximately every six years with the next season occurring from October 2017 – June 2019. Individual events have a duration of up to 8 hours, but the initial events will be short. Events occur with a cadence of half the binary orbital period of 4.28 days. Multiple events will be observable over the course of the 2018 apparition.

Patroclus-Menoetius is at opposition on 7 March 2018 with an apparent magnitude of 15.9.

A detailed set of predictions is available upon request from Will Grundy ([email protected]).

Patroclus and Menoetius are targets of the Lucy Discovery mission, planned for launch in October 2021. Observations of the mutual events will help refine the binary mutual orbit, which is critical for planning the encounter. We encourage any interested observers to communicate their plans to the Lucy Earth-based Observing Working group lead, Richard Binzel ([email protected]).