ASTROMETRIC ANALYSIS OF EUROPA-IO OCCULTATIONS OBSERVED IN 1991

Astrometric results from an analysis of 36 lightcurves of Io's occulta tions by Europa, observed during 1991 in the visible bands, are presen ted. They are issued from the adjustment of a theoretical astrometric- photometric model to observations using Hapke's law. These observation s are of importance because they give high quality astrometric informa tion useful to the determination of the location of Io's hotspots. In fact, accurate positionning of hotspots on Io is made possible from in frared observations only if the occultation timing is well-known.