Temporal survey of the Jovian auroral activity with IUE during Galileo G1/G2 orbit

R. Prangé (IAS, France), T. Livengood (University of Maryland), G. Chagnon, T. Fouchet (IAS, France), S. Maurice (OMP, France), S. Budzien (NRL), W. Harris (University of Wisconsin), P. Zarka (Observatoire de Meudon, France), M. Kivelson (UCLA), B. Kurth (University of Iowa)

It has been shown recently (Prangé et al., Icarus, 102, 9289, 1997) that IUE was a good indicator of the global auroral activity of Jupiter in the FUV. More than a month of observations (17 August - 25 September 1996) have been dedicated to the study of Jupiter in correlation with the end of Galileo's orbit G1 and beginning of orbit G2. One of the goals of the program was to perform for the first time a quasi-continuous monitoring of the FUV auroral activity. We will present the result of these observations, define an "auroral activity index", and show how it varies with time. Small variations of 10%-20% are observed on short time scales (<10 hours to tex2html_wrap_inline13 1 day). Larger variations, by a factor of 2 to 4 occur on timescales of 5 to 10 days. These variations will be compared to the solar wind activity, to the radio auroral activity of Jupiter, and to Galileo measurements taken during the same period.