Melin, H. and Stallard, T. and Miller, S. and Gustin, J. and Galand, M. and Badman, S. V. and Pryor, W. R. and O'donoghue, J. and Brown, R. H. and Baines, K. H. (2011) Simultaneous Cassini VIMS and UVIS observations of Saturn's southern aurora : comparing emissions from H, H2 and H3+ at a high spatial resolution. Geophysical Research Letters, 38 (15): L15203. ISSN 0094-8276
Abstract
Here, for the first time, temporally coincident and spatially overlapping Cassini VIMS and UVIS observations of Saturn's southern aurora are presented. Ultraviolet auroral H and H2 emissions from UVIS are compared to infrared H3+ emission from VIMS. The auroral emission is structured into three arcs – H, H2 and H3+ are morphologically identical in the bright main auroral oval (∼73°S), but there is an equatorward arc that is seen predominantly in H (∼70°S), and a poleward arc (∼74°S) that is seen mainly in H2 and H3+. These observations indicate that, for the main auroral oval, UV emission is a good proxy for the infrared H3+ morphology (and vice versa), but for emission either poleward or equatorward this is no longer true. Hence, simultaneous UV/IR observations are crucial for completing the picture of how the atmosphere interacts with the magnetosphere.