HST/STIS Observations of Ganymede's Auroral Ovals at Eastern Elongation

We report on new Space Telescope Imaging Spectrograph (STIS) observations of Ganymede s auroral emissions obtained (to be obtained) during two visits with the Hubble Space Telescope (HST). The observations of the first visit, a five orbits, were obtained on November 19, 2010 and the second visit, also a five orbits, is scheduled for opposition in October/November 2011. We will present results of the full campaign, in case of a successful execution of the second visit. Our observations cover more than half a cycle of system III longitudes of Ganymede s positions within Jupiter s magnetosphere for each visit. We analyze the observations with respect to brightness and locations of Ganymede auroral ovals. Our goal is to set constrains on the interaction of Ganymede s mini-magnetosphere with Jupiter s magnetosphere, Ganymede s magnetic field and plasma environment, and if possible on Ganymede s neutral atmosphere.