SIMULTANEOUS SPECTROSCOPY AND IMAGING OF THE JOVIAN AURORA WITH THE HOPKINS ULTRAVIOLET TELESCOPE AND THE HUBBLE-SPACE-TELESCOPE

Simultaneous ultraviolet spectra and images of the north polar aurora of Jupiter were obtained on 1995 March 9 with the Hopkins Ultraviolet Telescope (HUT) and the Hubble Space Telescope (HST). This unique data set contains a well-calibrated flux measurement that includes all of the H-2 Lyman and Werner band emission from 900 to 1650 Angstrom, as w ell as information about the spatial extent of the aurora. For these o bservations, we oriented the 10 '' x 57 '' slit of the HUT spectrograp h parallel to the equator of Jupiter so that it was underfilled by the aurora and minimally contaminated by extraneous reflected solar light from low to mid latitudes. The aurora was imaged simultaneously using the FIST Wide Field and Planetary Camera 2 (WFPC2). Images were taken through a Wood's filter and also through a Wood's filter/CaF2, filter combination. These images have recorded the aurora in the light of at omic and molecular hydrogen with relatively low reflected solar contam ination. The molecular hydrogen aurora is found to extend over 4.5 +/- 0.5 x 10(-10) sr, with an average brightness of 106 +/- 12 kR integra ted over the band of wavelengths from 900 to 1650 Angstrom, excluding H I lambda 1216. We measure a 13% larger emitting area (5.1 +/- 0.5 x 10(-10) sr) and significantly different morphology for the combined at omic and molecular hydrogen aurora (Ly alpha + H-2), although these di fferences could be a result of time variability. Color ratios derived from the data indicate a total auroral energy deposition rate of 13 er gs s(-1) cm(-2) by 3-30 keV electrons. We find little evidence for ion s as primary auroral particles in the HUT spectra. Our analysis places upper limits on sulfur ion emissions that are an order of magnitude l ower than those from the IUE observations, and, therefore, the emissio ns could be entirely from the Io torus in the background of the planet .