Juno-UVS observations of Jupiter's aurora and airglow emissions

The Ultraviolet Spectrograph (UVS) on Juno observes Jupiter's northern and southern auroras for several hours each during every perijove pass. On each pass the 7°-long slit of UVS is used to observe the jovian aurora in a series of swaths, with one swath for each 30-s spin of the Juno spacecraft. During these perijove periods, the range of Juno to the aurora drops from ˜6 R_J to ˜0.3 R_J (or less) in the north - and then reverses this in the south - so that spatial resolution and coverage change dramatically. A scan mirror points the UVS boresight at up to 30° from the Juno spin plane to enable targeting of different features or to build up context images by rastering over the auroral region. 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 only 3500-8000 km above the cloud tops, UVS is able to study Jupiter's airglow from within Jupiter's upper atmosphere. A variety of auroral 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 a large expanse of 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, we will also report on UVS airglow observations to date, with special attention to the Lyα emissions of atomic hydrogen.