High‐Z energetic particles at geosynchronous orbit during the Great Solar Proton Event Series of October 1989

Comparatively high levels of 2‐ to 50‐MeV ions of carbon, nitrogen, oxygen, neon, magnesium, silicon, sulphur, and iron have been identified at geosynchronous orbit by the synchronous orbit particle analyzer, the “SOPA” detector, on board the satellite 1989‐046, which became operational in September 1989. This detector is described, and time histories of some of the above mentioned ions are given for the solar energetic particle event series of late October 1989.