ULYSSES COSPIN/KET OBSERVATIONS OF JOVIAN ELECTRONS DURING THE DISTANT ULYSSES JUPITER FLYBY

摘要

Since launch in Oct. 1990 Ulysses sampled the He-liosphere between Earth and Jupiter in three dimensions continuously. With varying heliomagnetic distance to Jupiter and changing solar activity the Jovian electron population varied considerably during this time. In 1992 and 2004 Ulysses had two encounters with Jupiter allowing to study the propagation of Jovian electrons originating from an off-centre point source in the heliosphere. (These observations are crucial for evaluating and testing propagation models.) The closest approach to Jupiter was 0.003 AU in 1992 and 0.803 AU in 2004 (6 RJ and 1682 RJ respectively). In addition Jovian electron jets were observed in during both encounters in the 3-10 MeV range as events with sharp increase and decrease, strong anisotropy, and durations of up to a few hours. While the global observations have been discussed in Heber et al. (2005), the Jovian jet measurements made by the COSPIN KET as far out as 2.2 AU from the planet after the distant encounter in 2004 will be presented in this paper. A report of COSPIN HET measurements of jets has been given by McKibben et al. (2005).