Observations of Jupiter's 20-cm synchrotron emission during the impacts of Comet P/Shoemaker-Levy 9

Radio telescopes at Green Bank, West Virginia and Parkes, Australia observed Jupiter's 20-cm radiation before, during, and after the impacts of Comet P/Shoemaker-Levy 9. The average nonthermal intensity increased from about 5.3 Jy before the SL9 impacts to 6.4 Jy afterwards (normalized to 4.04 AU), and began decreasing exponentially after the impacts with a time scale of 115 +/- 15 days (assuming the radiation would return to preimpact levels). The degree of linear polarization increased from 24% before to 25% after the impacts and remained approximately constant after the impacts, The dependence of the nonthermal intensity and the degree of polarization on longitude (the beaming curve), stable before the impacts, varied erratically during the impact period, The variation of the nonthermal intensity with magnetic latitude grew flatter after the impacts, especially when the absolute values of magnetic latitudes were restricted to less than 7 degrees. (C) 1996 Academic Press, Inc.