CALAR-ALTO OBSERVATIONS OF SHOEMAKER-LEVY-9 - CHARACTERISTICS OF THE H-IMPACT AND L-IMPACT

We describe data obtained at Calar Alto's 3.5-meter and 2.2-meter telescopes during the impacts of SL9 fragments H and L with Jupiter. Both the H and L impact lightcurves display three major features which we call 1) the first precursor, 2) the second precursor, and 3) the main event. The peak of the first precursor occurs before the onset of the Galileo PPR signal for each impact. We identify these three features with 1) the bolide entry into the jovian atmosphere, 2) the rising impact fireball, and 3) reimpacting ejecta. We also identify faint spots that appear near the H and L impact sites just before the respective events and suggest that the pre-L spot was caused by the J fragment which vanished in December 1993.