Observations of Mercury's exosphere with the visible channels of PHEBUS during the first two Mercury flybys with the BepiColombo mission

BepiColombo has already performed two flybys of Mercury, the first one on October 1st 2021 and the second one on June 23rd 2022. During both flybys, the visible channels of PHEBUS (Probing of Hermean Exosphere By Ultraviolet Spectroscopy) were activated. The channel c404 is centered at the emission line of potassium at 404 nm while the other channel, c422, is centered at the emission line of calcium at 422 nm. During the first flyby, the visible channels were on for 1 hour, starting half an hour before the closest approach. During the second flyby, the visible channels were activated for 1h15, starting a quarter of an hour before the closest approach. The boresight of PHEBUS was in a fixed direction with respect to the stars during the whole sequence, pointing close to the north ecliptic pole and almost tangential to the limb at the equator. We observed Mercury’s extended exosphere of Ca beyond ~10,000 km. We have detected additional species with the channel c404 but comparison with previous studies is unconclusive and further analysis will be necessary to identify this species. These datasets contain the total count rate recorded by PHEBUS visible channels as well as the associated dark count rate and the uncertainty for the total count rate. Each dataset also contains information to reconstruct the geometry of observation (Mercury and BepiColombo positions, PHEBUS boresight and Sun direction). Each flyby has its own dataset.