Solar Origin of Anisotropic Electron Events observed by ULYSSES and ACE

Abstract

We investigate the solar origin of energetic collimated electron events observed in situ by the EPAM and/or HISCALE particle experiments aboard the ACE and ULYSSES spacecraft, respectively. This study has been performed for two months, September and October 1999 when Ulysses was magnetically connected to the solar disk at heliolongitudes visible at the Earth. The two spacecraft were separated by about 35° in latitude and up to 60° in longitude. In this paper, results are described for one period only, October 24 November 1, 1999. It is found that not all the anisotropic events are observed by both spacecrafts; there exists a strong dependence on the spacecraft's magnetic connection back to the Sun.