Auroral emissions provide an indispensable diagnostic tool for the energetic processes occurring in planetary magnetospheres. In 2009 Saturn will reach equinox for the first time since the advent of high-sensitivity planetary ultraviolet (UV) auroral imaging, offering a unique, transient opportunity to observe both polar auroral regions simultaneously. The observations proposed here will not only provide the best images to date of Saturn|*|s northern auroras, they will address three fundamental issues: (1) Are Saturn|*|s auroras similar in the north and south? This will reveal the nature of the processes that cause the northern auroras, and verify the multipole nature of Saturn|*|s internal magnetic field. (2) Is the location of the northern auroral emission symmetric with to the south? This will indicate why the southern auroral oval is displaced a few degrees toward midnight from the spin pole. It will also reveal whether the oscillation observed in the location of the southern auroral oval is similarly observed in the north, illuminating the nature of near-planetary period oscillations observed throughout the magnetosphere and potentially providing a value for the elusive rotation period of the deep interior. (3) What is the influence of equinox on the magnetosphere? The unique orientation of the planetary spin axis at equinox will reveal whether the auroras are influenced by the direction of the interplanetary magnetic field, and whether the Sun|*|s effect on Saturn|*|s magnetosphere changes throughout the planet|*|s seasons. The Hubble Space Telescope is the only instrument capable of providing global instantaneous coverage of Saturn|*|s UV auroras, and since Saturn|*|s orbital period is ~30 years, Cycle 17 is the only opportunity to make these observations. These observations can be obtained with either the Solar Blind Channel (SBC) of the ACS or STIS/FUV-MAMA, such that if one is not functioning the other may be used. The fields of view of both ACS/SBC (35|*| by 31|*|) and STIS/FUV-MAMA (25|*| by 25|*|) are large enough to encompass the whole disc of the planet plus a significant portion of the rings. In practice we prefer to use the ACS, since the sensitivity using the F125LP filter is ~0.0015 counts/pixel/s for 1 kiloRayleigh of H2 plus Lyman-alpha emission, versus ~0.0005 counts/pixel/s for STIS using the equivalent F25-SrF2 filter. We will use the F125LP filter in order to observe the UV auroral emission whilst reducing Ly-alpha background contamination from the geocorona. For a similar reason the observations are to be obtained whilst HST is in shadow. Higher count rates are desirable since planetary rotation introduces ~1D/100 s of blurring of features near the central meridian longitude. Previously measured count rates are ~25,000 counts/s, well below the limit of 200,000 counts/s. We will obtain 100 s exposures, a length experience shows is sufficient to obtain a good signal-to-noise ratio. We request 12 orbits, consisting of two groups spaced ~14 days apart in order to observe during periods of opposite IMF polarity (the solar rotation period is ~27 days). Each group consists of six orbits spaced over ~24 h. This cadence is requested in order to appropriately sample the ~10.7 h rotation of the auroral ovals within the time constraints of the orbit of HST. SOLAR SYSTEM 12 false false false false 0.0 0.0 SUPPORTED SOLAR SYSTEM PLANET PLANET SATURN STD=SATURN EARTH ACS/SBC Imaging No No F125LP ACS/SBC Imaging No No F125LP Using ephemeris for target 11566-A1-SATURN ephemeris data for target 11566-A1-SATURN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.220 to 10.182. ephemeris interval: 08.152 to 10.152 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. This Visit is scheduled to coincide with the Cassini UVIS/VIMS auroral observation between 0728 UT and 1415 UT on DoY 23 ( = 0840 - 1527 UT @ Earth). Note, we've scheduled the visit for the full day, but based on past experience once we know the orbit of HST closer to the time we should be able to constrain the time better. 1232749287000 291.2149550559895 (Tic-Visit :proposal-id 11566 :visit-id "A1" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 10:32:29.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 351760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11566 :visit-id "A1" :obset-id "A1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11566 :visit-id "A1" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2728 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 Using ephemeris for target 11566-A2-SATURN ephemeris data for target 11566-A2-SATURN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.220 to 10.182. ephemeris interval: 08.152 to 10.152 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. This Visit is scheduled to coincide with the Cassini UVIS/VIMS auroral observation between 0728 UT and 1415 UT on DoY 23 ( = 0840 - 1527 UT @ Earth). Note, we've scheduled the visit for the full day, but based on past experience once we know the orbit of HST closer to the time we should be able to constrain the time better. (visit moved to day 27 to avoid conflicts) 1233082990000 290.3647144284306 (Tic-Visit :proposal-id 11566 :visit-id "A2" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 10:29:59.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 351760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11566 :visit-id "A2" :obset-id "A2" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11566 :visit-id "A2" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2728 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 Using ephemeris for target 11566-A3-SATURN ephemeris data for target 11566-A3-SATURN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.220 to 10.182. ephemeris interval: 08.152 to 10.152 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. This Visit is scheduled to coincide with the Cassini UVIS auroral observation between 0728 UT and 2108 UT on DoY 24 ( = 0840 - 2220 UT @ Earth). Note, we've scheduled the visit for the full day, but based on past experience once we know the orbit of HST closer to the time we should be able to constrain the time better. 1232818326000 292.57335901640533 (Tic-Visit :proposal-id 11566 :visit-id "A3" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 10:32:38.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 351760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11566 :visit-id "A3" :obset-id "A3" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11566 :visit-id "A3" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2728 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 Using ephemeris for target 11566-A4-SATURN ephemeris data for target 11566-A4-SATURN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.220 to 10.182. ephemeris interval: 08.152 to 10.152 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. This Visit is scheduled to coincide with the Cassini UVIS auroral observation between 0728 UT and 21:08 UT on DoY 24 ( = 0840 - 2220 UT @ Earth). Note, we've scheduled the visit for the full day, but based on past experience once we know the orbit of HST closer to the time we should be able to constrain the time better. 1232829832000 292.57288244370557 (Tic-Visit :proposal-id 11566 :visit-id "A4" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 10:32:39.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 351760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11566 :visit-id "A4" :obset-id "A4" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11566 :visit-id "A4" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2728 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 Using ephemeris for target 11566-A5-SATURN ephemeris data for target 11566-A5-SATURN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.220 to 10.182. ephemeris interval: 08.152 to 10.152 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. This Visit is scheduled to coincide with the Cassini UVIS auroral observation between 0843 UT and 2053 UT on DoY 25 ( = 0945 - 0005 (DoY 26) UT @ Earth). Note, we've scheduled the visit for the full day, but based on past experience once we know the orbit of HST closer to the time we should be able to constrain the time better. 1233077236000 289.15251747928517 (Tic-Visit :proposal-id 11566 :visit-id "A5" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 10:32:40.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 351760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11566 :visit-id "A5" :obset-id "A5" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11566 :visit-id "A5" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2728 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 Using ephemeris for target 11566-A6-SATURN ephemeris data for target 11566-A6-SATURN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.220 to 10.182. ephemeris interval: 08.152 to 10.152 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. This Visit is scheduled to coincide with the Cassini UVIS auroral observation between 0843 UT and 2053 UT on DoY 25 ( = 0945 - 0005 (DoY 26) UT @ Earth). Note, we've scheduled the visit for the full day, but based on past experience once we know the orbit of HST closer to the time we should be able to constrain the time better. 1233094498000 289.15170902373177 (Tic-Visit :proposal-id 11566 :visit-id "A6" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 10:32:42.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 351760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11566 :visit-id "A6" :obset-id "A6" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11566 :visit-id "A6" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2728 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 Using ephemeris for target 11566-B1-SATURN ephemeris data for target 11566-B1-SATURN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.220 to 10.182. ephemeris interval: 08.152 to 10.152 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. 1233998020000 276.5859428356233 (Tic-Visit :proposal-id 11566 :visit-id "B1" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 10:32:43.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 351760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11566 :visit-id "B1" :obset-id "B1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11566 :visit-id "B1" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2728 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 Using ephemeris for target 11566-B2-SATURN ephemeris data for target 11566-B2-SATURN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.220 to 10.182. ephemeris interval: 08.152 to 10.152 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. 1234015285000 289.5463037728909 (Tic-Visit :proposal-id 11566 :visit-id "B2" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 10:32:45.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 351760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11566 :visit-id "B2" :obset-id "B2" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11566 :visit-id "B2" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2728 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 Using ephemeris for target 11566-B3-SATURN ephemeris data for target 11566-B3-SATURN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.220 to 10.182. ephemeris interval: 08.152 to 10.152 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. This Visit is scheduled to coincide with the Cassini UVIS auroral observation between 1659 UT on DoY 39 and 0324 UT on DoY 40 ( = 1811 (DoY 39) - 0436 (DoY 40) UT @ Earth). Note, we've scheduled the visit for the full day, but based on past experience once we know the orbit of HST closer to the time we should be able to constrain the time better. 1234084341000 284.8714726645973 (Tic-Visit :proposal-id 11566 :visit-id "B3" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 10:32:47.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 351760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11566 :visit-id "B3" :obset-id "B3" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11566 :visit-id "B3" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2728 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 Using ephemeris for target 11566-B4-SATURN ephemeris data for target 11566-B4-SATURN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.220 to 10.182. ephemeris interval: 08.152 to 10.152 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. This Visit is scheduled to coincide with the Cassini UVIS auroral observation between 1659 UT on DoY 39 and 0324 UT on DoY 40 ( = 1811 (DoY 39) - 0436 (DoY 40) UT @ Earth). Note, we've scheduled the visit for the full day, but based on past experience once we know the orbit of HST closer to the time we should be able to constrain the time better. 1234095850000 284.8707064740923 (Tic-Visit :proposal-id 11566 :visit-id "B4" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 10:32:48.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 351760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11566 :visit-id "B4" :obset-id "B4" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11566 :visit-id "B4" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2728 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 Using ephemeris for target 11566-B5-SATURN ephemeris data for target 11566-B5-SATURN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.220 to 10.182. ephemeris interval: 08.152 to 10.152 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. This Visit is scheduled to coincide with the Cassini UVIS auroral observation between 1659 UT on DoY 39 and 0324 UT on DoY 40 ( = 1811 (DoY 39) - 0436 (DoY 40) UT @ Earth). Note, we've scheduled the visit for the full day, but based on past experience once we know the orbit of HST closer to the time we should be able to constrain the time better. 1234164905000 275.7925674541873 (Tic-Visit :proposal-id 11566 :visit-id "B5" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 10:32:49.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 351760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11566 :visit-id "B5" :obset-id "B5" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11566 :visit-id "B5" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2728 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 Using ephemeris for target 11566-B6-SATURN ephemeris data for target 11566-B6-SATURN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.220 to 10.182. ephemeris interval: 08.152 to 10.152 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. This Visit is scheduled to coincide with the Cassini UVIS auroral observation between 1659 UT on DoY 39 and 0324 UT on DoY 40 ( = 1811 (DoY 39) - 0436 (DoY 40) UT @ Earth). Note, we've scheduled the visit for the full day, but based on past experience once we know the orbit of HST closer to the time we should be able to constrain the time better. 1234170659000 275.7921761100811 (Tic-Visit :proposal-id 11566 :visit-id "B6" :proposal-version -1 :trans-version "20080609" :date "26-Jun-2008 10:32:51.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 351760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11566 :visit-id "B6" :obset-id "B6" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11566 :visit-id "B6" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2728 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0