Juno-UVS Observations of Jupiter's Aurora and Airglow Emissions

Juno’s Ultraviolet Spectrograph (UVS) observes Jovian auroras for about 10 hours centered on closest approach during each perijove pass. On each pass, we use the 7˚-long slit of UVS to observe Jupiter in a series of swaths, with one swath per ~30s spin of the Juno spacecraft. During these perijove periods, the range of Juno to the aurora drops from ~6 RJ  to ~0.3 RJ or less in the north (and then reverses this in the south), so that spatial resolution and coverage change dramatically. A scan mirror on UVS is used to target different features or raster across the auroral region to build up context images. A variety of forms and activity levels can be identified in the Juno-UVS data; some of these have been described before with HST observations, but others are new. One new result is that certain polar emissions may be excited by low-energy ionospheric electrons (and thus would be unrelated to precipitating particles). Recent results and comparisons with simultaneous Chandra observations at x-ray wavelengths will be presented here. In addition, during the time period between observations of the northern and southern auroral regions, low-latitude airglow observations are possible. Since Juno perijove altitudes are 3500-8000 km above the cloud tops, UVS is able to study Jupiter’s airglow from within Jupiter’s upper atmosphere. In this talk we will also report on UVS airglow observations to date, with special attention to the Lyα emissions of atomic hydrogen.