FIGURE 3. Simultaneous Cassini and Galileo observations of the jovian magnetopause.

In the upper panel, Cassini radio and plasma wave observations show trapped continuum radiation at the beginning of the plotted interval with a low-frequency cutoff of about 300 Hz. The magnetopause crossing time indicated on the spectrogram was determined on the basis of the disappearance of the continuum radiation, changes in the magnetic-field direction and spectrum, and the low-energy plasma, and energetic-particle distributions (D. Mitchell, personal communication). In the bottom panel, similar observations from the Galileo plasma wave instrument are shown. Here the lowest cutoff frequency is somewhat higher than at Cassini.