Mémoire

Abstract

The binary Trojan asteroid system (617) Patroclus–Menoetius is of particular scientific interest due to its role in constraining models of Solar System formation and its upcoming observation by NASA’s Lucy mission. In this work, a comprehensive observational and photometric study of this system is presented. Three types of observations were conducted from September to October 2024 on the TRAPPIST telescopes : mutual events photometry, long-duration photometry, and color indices retrieval from multi-filter photometry (BVRI). Six mutual events were successfully observed and analyzed. The resulting light curves were categorized into two main morphologies: narrow and symmetrical, and wide and asymmetrical. Links between the nature of the events, i.e., partial or central, occultations or eclipses, were made. Long-duration photometry of the system was further analyzed to extract the rotation period of Patroclus. Using the a Fourier-based fitting model and the Photometry Pipeline photomet- ric reduction, two strategies—one using H magnitudes and the other using detrended reduced magnitudes—were applied, confirming the 102-hour period previously reported in the literature. Additionally, color-based taxonomic analysis using B-V, V-R, and V-I indices assigned the system to the X-class, in agreement with earlier studies. Overall, this work not only provides refined photometric characterizations of the Patroclus–Menoetius system but also supports the Lucy mission’s scientific objectives. The results contribute to broader understanding of Trojan asteroid properties.