Multi-spacecraft observations of solar energetic electron events during the rising phase of solar cycle 24

Abstract

We analyze impulsive electron events in the energy range of a few tens to a few hundred keV which were observed during the rising phase of solar cycle 24 onboard the two STEREO spacecraft as well as on spacecraft located near the Earth. A sequence of events in May 2007 when all spacecraft were still close together is used for an intercalibration of electron fluxes measured by the STEREO Solar Electron and Proton Telescope (SEPT) with instruments covering similar energy ranges on Wind/ACE/SOHO. We also present a method which allows, under some restrictions, to reconstruct the angular distributions of electrons from the four viewing directions provided by the SEPT instrument. For a number of electron events observed from May 2009 to 2011 during which the longitudinal separation of the two STEREO spacecraft increased from 120 to 180 degrees time profiles, onset times, anisotropies and spectra observed by the different spacecraft are compared, and their dependencies with the angular separation (in both, longitude and latitude) of the spacecraft footpoints with respect to the source active region are discussed. Evidence for lateral transport in the solar corona or in the interplanetary magnetic field is investigated.

Publication
Proceedings of the 32nd International Cosmic Ray Conference, ICRC 2011