Comprehensive auroral imaging of Saturn during the International Heliophysical Year

As part of the International Heliophysical Year in 2007, a large-scale campaign is planned to observe the UV auroras of Jupiter and Saturn with the Hubble Space Telescope (HST). In this talk we will provide an overview of the Saturn campaign. Previous HST observations of Saturn's auroras have greatly extended our knowledge of the processes that occur in the planet's magnetosphere. In particular, Saturn's main oval auroras vary much more than Jupiter's in terms of latitudinal position and extent, and have been shown to be correlated with the conditions in the solar wind. However, these campaigns have generally been limited by their short-term nature, and in order to establish exactly how the auroras depend on the solar wind we must make observations continually over at least one complete solar rotation. This is the goal of the 2007 campaign, in which Saturn will be observed for a period of 30 days in January and February. The timing is fortuitous since not only will the planet be in opposition, allowing near-Earth measurements of the interplanetary medium to be extrapolated to Saturn's orbit, the Cassini spacecraft will be in a position to obtain in-situ plasma and magnetic field measurements from the magnetosphere and solar wind. Cassini will also make observations of Saturn's UV and SKR emissions throughout the campaign, and the planet will be observed by ground-based IR and radio telescopes. Here we provide a brief review of our current understanding of Saturn's auroras, along with an overview of the coordinated observations planned at Saturn and the key science goals we aim to address.