A search for natural satellites of Mercury

We present the results of an imaging survey of Mercuryʹs Hill sphere in search for objects dynamically bound to the planet, motivated by the existence of hermeocentric orbits that have been shown to be stable over 5 Myr or more. A six-day survey of Mercuryʹs apparent vicinity from 6 to 140 Mercury radii, with full coverage between 19 and 73 Mercury radii, was performed with the Nordic Optical Telescope using ALFOSC in the R-band. The deepest limiting magnitude of 18.6 at a signal-to-noise-level of 3 corresponds to a hermeocentric object size of 0.5 km, while the brightest limiting magnitude corresponds to a size of 1.6 km. While two suspected sources were found, no hermeocentric objects could be confidently identified.