Directivity of Saturn electrostatic discharges and ionospheric implications

From a detailed analysis of the intensity distribution of Saturn electrostatic discharges (SED) as a function of time during the Voyager 1 encounter with Saturn, the total beaming pattern of the SED source, which is found to be isotropic, is determined. This result allows for the derivation of the diurnal variations of the peak electron density over the dayside equatorial ionosphere of Saturn, and thus explains the puzzling features observed during the Voyager 1 encounter with Saturn - the longer extent of the SED visibility afer closest approach and the existence of double-humped SED episodes before the encounter - by ionospheric absorption of the SED radio emission. 18 references