PHEBUS observations of the He 58.4 nm emission during Bepi Colombo's first Mercury Flyby
Abstract
We present observations of the He 58.4 nm emission performed with the EUV channel of the PHEBUS spectrometer on board ESA’s Mercury Planetary Orbiter during Bepi Colombo’s first Mercury Flyby in October 2021. We describe the data analysis and PHEBUS EUV calibration based on interplanetary He 58.4 nm data from observations during the cruise. We discuss the results in comparison with Mariner 10 measurements at 58.4 nm and models of Mercury’s exosphere.