3462 20180129162631.0 SEMIN-2018-0015 Katsiyannis, Thanassis The detection of ultra-relativistic electrons in low Earth orbit 2017 2017-02-24 The analysis of energetic particles, indirectly detected by LYRA will be presented. Combining EPT (Energetic Particle Telescope, on-board PROBA-V) observations with LYRA data for an overlapping period of time, we identified these particles as electrons with an energy range of 2 to 8 MeV. The observed events are strongly correlated to geomagnetic activity and appear even during modest disturbances. They are also well confined geographically within the L=6 McIlwain zone, which makes it possible to identify the source. Some enigmatic characteristics of these observations will also be presented and discussed. STCE Royal Observatory of Belgium thanassis.katsiyannis@observatoire.be SEMIN