Continuous Monitoring of Jupiter's Aurora and Io Plasma Torus with the Hisaki Satellite during Joint Observing Campaign with Juno

The Hisaki satellite is the first space telescope that is dedicated to observations of our solar system bodies. Hisaki has been continuously monitoring the atmosphere and magnetosphere of the solar system bodies with the extreme ultraviolet (EUV) spectroscope EXCEED since the launch in September 2013. Dynamics on timescales from 10s minutes to a few years were discovered in the atmosphere and magnetosphere by the continuous monitoring. Large joint observing campaigns for Jupiter by the Juno spacecraft in coordination with Hisaki, the Hubble Space Telescope (HST), and other facilities started in mid-2016. Before Jupiter Orbit Insertion, Juno made the in-situ solar wind measurements while Hisaki was simultaneously monitoring Jupiter's aurora and Io plasma torus. On Day of Year 142, Hisaki discovered that the EUV auroral emission power rapidly increased by a factor of ~3 but returned to a nominal level within one planetary rotation. The transient aurora was followed by brightening of the torus sulfur and oxygen ions that is proxy of the hot electron populations in the torus. At the same time, the relatively weak solar wind shock signatures were found in the JUNO/JEDI energetic particle data (Clark et al.). The transient variability is compared to the morphology observed by HST (Nichols et al.). Hisaki is going to monitor Jupiter in collaboration with the large observing program of HST (Grodent et al.) that will make ~150 exposures from this November.