  We report on dust measurements obtained during the seventh orbit of the
Galileo spacecraft about Jupiter. %which had a close flyby at Ganymede. The
most prominent features observed are highly time variable dust streams recorded
throughout the Jovian system. The impact rate varied by more than an order of
magnitude with a 5 and 10 hour periodicity, which shows a correlation with
Galileo's position relative to the Jovian magnetic field. This behavior can be
qualitatively explained by strong coupling of nanometer-sized dust to the
Jovian magnetic field. In addition to the 5 and 10 h periodicities, a longer
period which is compatible with Io's orbital period is evident in the dust
impact rate. This feature indicates that Io most likely is the source of the
dust streams. During a close (3,095 km altitude) flyby at Ganymede on 5 April
1997 an enhanced rate of dust impacts has been observed, which suggests that
Ganymede is a source of ejecta particles. Within a distance of about 25 $\rm
R_J$ (Jupiter radius, $\rm R_J = 71,492$ km) from Jupiter impacts of
micrometer-sized particles have been recorded which could be particles on bound
orbits about Jupiter.
