----- Submission 1 (Tue Oct 21 16:09:02 GMT 2003) ----- Jovian Satellites The icy Galilean satellites form an integral but poorly understood component of Jupiter's magnetospheric system. While the Pioneer and Voyager spacecraft encounters yielded evidence for the existence of a source of oxygen ions beyond Io's orbit, conclusive evidence that Europa and Ganymede possess thin oxygen atmospheres was only recently provided by HST/GHRS detections of faint far-UV airglow emissions of OI. Moreover, the OI emission on Ganymede is localized to the region of the satellite's poles, consistent with an auroral excitation source that would be expected from the internal magnetic field of Ganymede. More recently, spectrally resolved images of Ganymede obtained with STIS have confirmed this result and demonstrated the variation in location and brightness of the OI emissions with the position of Ganymede relative to Jupiter's plasmasheet. The energy and source of the exciting electrons remain unknown and there is little or no relevant in situ Galileo data that bear directly on this question and thus the determination of the molecular abundance remains highly uncertain. However, the energy can be constrained by the observation of the forbidden OI red line at 6300 Ang, but this requires observation when the satellite is in Jupiter's shadow, to avoid the emissions being swamped by the strong solar reflected light. Europa similarly shows the UV OI emissions, and recent HST/STIS observations show a complex time-dependent variation in the spatial distribution of these emissions. Europa does not have an intrinsic magnetic field, but rather the Jovian field at Europa is modified by a magnetic field induced by Europa's rotation. We will investigate Kivelson's suggested European conducting ocean by timing observations to coincide with different orientations of the induced magnetic field.
The sequence of observations is as follows: Each visit consists of one orbit of HRC observations of Ganymede in eclipse to observe OI 6300 A emissions together with two orbits of SBC observations either before or after eclipse to observe the UV oxygen emissions. Two additional orbits of STIS spectroscopy are used to verify the spectral content of the SBC images. Observations should be made near either elongation of Jupiter so as to maximize the satellite time in eclipse and angular separation from Jupiter. The sequence of exposures is different for western elongation (pre-opposition) than for eastern elongation (post- opposition). Thus there are two observing windows, each of about three months, each year. None 12 false false false false SUPPORTED SOLAR SYSTEM Cycle 12 target. SURF(V) = 5.80, B-V = 0.83 SATELLITE Ganymede STD=JUPITER STD=GANYMEDE OLG OF GANYMEDE FROM EARTH BETWEEN 310.0 360.0 SOLAR SYSTEM Cycle 12 target. Ganymede in eclipse during one orbit. A pre-opposition eclipse observation should occur within +/- 1.5 months of December 8, 2003. Ganymede should be located in HRC aperture so that disk of Jupiter is excluded. SURF(V) = 5.80, B-V = 0.83 SATELLITE Ganymede STD=JUPITER STD=GANYMEDE OLG OF GANYMEDE FROM EARTH BETWEEN 310.0 360.0, ECL U OF GANYMEDE BY JUPITER, SEP OF JUPITER GANYMEDE FROM EARTH GT 30.0" This observation can be made either pre- or post Jupiter opposition. For the pre-opposition case each visit consists of two orbits of STIS spectroscopy followed by two orbits of ACS/SBC observations followed by one orbit of ACS/HRC observations of Ganymede in eclipse. For the post-opposition case each visit consists of one orbit of ACS/HRC observations of Ganymede in eclipse followed by two orbits of ACS/SBC observations and two orbits of STIS spectroscopy following eclipse egress. The exposure sequence given here is for PRE-OPPOSITION. (Tic-Visit :proposal-id 9296 :visit-id "01" :proposal-version -1 :trans-version "20030713" :date "21-Oct-2003 11:40:16.0" :trans-errors '(:WARNINGS 1 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 758000 :tdrss-contact-duration 0 ) (Tic-Obset :proposal-id 9296 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 9296 :visit-id "01" :obset-id "A1" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 9296 :visit-id "01" :obset-id "B1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 9296 :visit-id "01" :orbit-number 1 :pcs-time 365 :si-vis-utilization 2636 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3004 :pcs-gap 0 ) (Tic-Orbit :proposal-id 9296 :visit-id "01" :orbit-number 2 :pcs-time 300 :si-vis-utilization 2679 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3004 :pcs-gap 0 ) (Tic-Orbit :proposal-id 9296 :visit-id "01" :orbit-number 3 :pcs-time 365 :si-vis-utilization 2607 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3004 :pcs-gap 0 ) (Tic-Orbit :proposal-id 9296 :visit-id "01" :orbit-number 4 :pcs-time 300 :si-vis-utilization 2643 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3004 :pcs-gap 0 ) (Tic-Orbit :proposal-id 9296 :visit-id "01" :orbit-number 5 :pcs-time 300 :si-vis-utilization 2688 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3004 :pcs-gap 0 ) true first orbit first orbit first orbit second orbit second orbit third orbit third orbit fourth orbit fourth orbit fifth orbit fifth orbit