Energetic Electron Patterns in the New SLS5 Longitude System

Abstract

Energetic electron (110–300 keV) fluxes collected during the entire 13‐year Cassini mission are organized in the new Saturn longitude system (SLS5). This system is based on Saturn radio emissions, varies slowly in time and has a north and a south branch. When the fluxes are organized in SLS5 longitudes and magnetodisk coordinates, they display an m=1 wave pattern that is quasi‐linear in longitude‐range maps. These spiral patterns are easily recognized in energetic electrons and have positive slopes a few degrees of longitude per RS (1 RS =60,268 km), similar to that observed in both particles and magnetic fields earlier in the mission. The patterns are most prominent at elevations +2 RS (SLS5 north) or −2 RS (SLS5 south) relative to the magnetodisk center. The results indicate the persistence of this pattern for essentially half a Saturnian year, suggesting that this pattern is a quasi‐permanent feature of the magnetosphere, much the same as its plasma sheet or magnetopause.