PLASMA ELECTRON SIGNATURES OF MAGNETIC CONNECTION TO THE JOVIAN BOW SHOCK - ULYSSES OBSERVATIONS

Ulysses plasma electron observations of bidirectional and enhanced unidirectional electron heat fluxes within 4500 R(J) (0.8 a.u. or 3 months on either side of closest approach) of Jupiter are presented as evidence for the magnetic connection of the spacecraft to the Jovian bow shock. These bursts of suprathermal electrons (>30 eV) are observed when the interplanetary magnetic field points roughly parallel or anti-parallel to the Jupiter-spacecraft line. Ninety-eight possible connection events were found over the 6 month period centered on the closest approach to Jupiter. The frequency of occurrence peaked with proximity to the bow shock, with most events occurring post-encounter. These are the first observations of backstreaming suprathermal electrons made in the vicinity of the Jovian bow shock.