PECULIAR OSCILLATIONS IN THE MICROWAVE EMISSION OF JUPITER DURING THEIMPACT OF K-FRAGMENT OF COMET SHOEMAKER-LEVY-9

In this article we report the peculiar oscillations in the intensity o f microwave (4.15 GHz) emission seen during the impact of K fragment o f comet Shoemaker-Levy 9 on July 19, 1994. The oscillations begin at 1 0h 13m 25s UT suddenly with a frequency of similar to 0.3 Hz and gradu ally the frequency of these oscillations increases to similar to 1 Hz. The oscillations are not due to local atmosphere or the radio interfe rence from signals of geostationary satellite. They are intrinsic to t he microwave emission from Jupiter during the impact of K fragment. Pe ak-to-peak amplitude of the oscillations is about 34% of the total mic rowave emission from Jupiter. If we assume that only 50% of the microw ave emission is non-thermal and only the non-thermal emission suffered oscillations, then the oscillations are about 68% of the non-thermal emission from Jupiter. The observations also indicate that there are t hree continuum enhancements during this event and periodic oscillation s almost all through. The third enhancement was the largest and during this enhancement there were some additional aperiodic variations. The aperiodic variations were of the order of few minutes and were possib ly generated by the gravity waves. The periodic oscillations could be synchrotron emission modulated by the plasma oscillation in the outer magnetosphere.