3577 20180920143419.0 POSTER-2018-0046 Katsiyannis, Athanassios C. The in-situ detection of ultra-relativistic electrons by LYRA, an UV radiometer on board PROBA2 2018 2018-11-09 The Large Yield RAdiometer (LYRA) instrument on board ESA's Project for On-board Autonomy 2 (PROBA2) satellite is a UV light radiometer designed to observe the Sun in four pass bands. Nevertheless, although the instrument had not been designed for in-situ detection, Katsiyannis et al (2018) reported detections of relativistic electrons from two of the four LYRA optical channels. This presentation will discuss the potential, the opportunities but also the challenges that arise form the use of EUV radiometers as in-situ electron detectors. 2STCE_PHYSSOL/ 2STCE_PHYSSOL/ 2STCE_PHYSSOL STCE Dominique, Marie European Space Weather Week, Leuven thanassis.katsiyannis@observatoire.be http://www.stce.be/esww15/ CPOSTER