We present the first complete multiband observations of a binary asteroid mutual event .
We obtained high-cadence , high-signal-to-noise photometry of the UT 2018 April 9 inferior shadowing event in the Jupiter Trojan binary system Patroclus-Menoetius in four Sloan bands — g ^ { \prime } , r ^ { \prime } , i ^ { \prime } , and z ^ { \prime } .
We use an eclipse lightcurve model to fit for a precise mid-eclipse time and estimate the minimum separation of the two eclipsing components during the event .
Our best-fit mid-eclipse time of 2458217.80943 ^ { +0.00057 } _ { -0.00050 } is 19 minutes later than the prediction of Grundy et al . ( 8 ) ; the minimum separation between the center of Menoetius ’ shadow and the center of Patroclus is 72.5 \pm 0.7 km — slightly larger than the predicted 69.5 km .
Using the derived lightcurves , we find no evidence for significant albedo variations or large-scale topographic features on the Earth-facing hemisphere and limb of Patroclus .
We also apply the technique of eclipse mapping to place an upper bound of \sim 0.15 mag on wide-scale surface color variability across Patroclus .