Observation of Relativistic Electron Precipitation Events with CALET on the International Space Station

The CALorimetric Electron Telescope (CALET) is a high-energy astroparticle physics experiment conceived for studying the origin of galactic cosmic rays. Installed on the International Space Station and taking data since October 2015, CALET is also able to provide a continuous monitoring of the near-Earth radiation environment, including solar energetic particle and relativistic electron precipitation (REP) events. In this work we present preliminary results of the REP measurements made over a ~4.5-year acquisition time (October 2015 May 2020), investigating their occurrence in relation to the solar wind and geomagnetic drivers. We also take advantage of a multi-spacecraft study using the twin Van Allen Probe to identify the plasma wave populations generated near the magnetic equator which are potentially responsible for the precipitation observed by CALET in low-Earth orbit.