We present the analysis of a large solar near-relativistic (NR; > 50 keV) electron event observed by the Electron, Proton and Alpha Monitor (EPAM) on board the ACE spacecraft on 1998 April 20. The particle event showed a rapid rise phase with onset at about 10:30 UT. It was preceded by a prominence eruption which was observed at the southwest limb of the Sun, where an M1.4 X-ray flare was also reported at 10:00 UT. A fast (1863 km/s) CME was first seen above 3 solar radii at 10:07 UT. Distinct radio emission episodes were observed. Those included a moving type IV burst between 9:40 and 10:00 UT, followed by a series of DH type III bursts observed below 2 MHz and a type II burst at 5-10 MHz. Several hours after these emissions a series of bursts was observed above the western limb at 164 MHz.
We use a particle transport model to infer the propagation conditions in the interplanetary medium and the injection history of the NR electrons observed in-situ. The simulation results reveal an extended and sparse release of particles. The first release occurs at 10:20 UT, during the brightest group of type III bursts. Other later sporadic release episodes are obtained. A later release episode appears after 13:00 UT, at about the time when bursty emission above the west solar limb becomes visible at 164 MHz.
This work is carried out within the SEPServer project (funded by the European Union through its FP7), which aims at facilitating the joint study of in situ measurements of energetic particles and the related electromagnetic signatures in the corona.