3410 20180116111955.0 POSTER-2018-0020 Katsiyannis, Athanassios LYRA/EPT Perturbations Project 2017 2017-11-28 To better understand the radiation environment in low Earth orbit (LEO), the analysis of in-situ observations of a variety of particles, at different atmospheric heights, and in a wide range of energies, is needed. We present an analysis of energetic particles, indirectly detected by the Large Yield RAdiometer (LYRA) instrument on board ESA's Project for On-board Autonomy 2 (PROBA2) satellite as background signal. Combining Energetic Particle Telescope (EPT) 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 geo-magnetic 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 their source. Although highly energetic particles are commonly disturbing data acquisition of space instruments, we show in this work that ultra-relativistic electrons with energies in the range of 2-8 MeV are detected only at high latitudes, while not present in the South Atlantic Anomaly region. 3PRODSIDCEXPLOIT/ 3PRODSIDCEXPLOIT/ 3PRODSIDCEXPLOIT STCE Dominique, Marie Pierrard, Viviane Lopez Rosson, Graciela De Keyser, Johan Berghmans, David Kruglanski, Michel Dammasch, Ingolf De Donder, Erwin 14th European Space Weather Week, Oostende thanassis.katsiyannis@observatoire.be CPOSTER