6854( 21) - 11/05/97 17:00 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6854 Version: 21 Check-in Date: 05-Nov-1997 16:59:35 1.Proposal Title: SATURN'S AURORA AND AIRGLOW ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GTO/WF2 6 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: John Trauger Jet Propulsion Laboratory CoI: Jeremy Mould Mt. Stromlo and Siding Spring Observatory N CoI: James Westphal California Institute of Technology N CoI: John Clarke University of Michigan N CoI: Gilda Ballester University of Michigan N CoI: Karl Stapelfeldt Jet Propulsion Laboratory N CoI: Christopher Burrows Space Telescope Science Institute N CoI: David Crisp Jet Propulsion Laboratory N CoI: John Gallagher University of Wisconsin-Madison N CoI: Richard Griffiths Johns Hopkins University N CoI: Jeff Hester Arizona State University N CoI: John Hoessel University of Wisconsin-Madison N CoI: Jon Holtzman Lowell Observatory N ------------------------------------------------------------------------------------ 5. Abstract We will observe Saturn's far-ultraviolet auroral emissions in the H Ly alpha (1216 Angstrom) and H2 Lyman and Werner (900-1650 Angstrom) emission bands with STIS in its MAMA imaging and spectroscopic modes. In cycles 6 and 7 the geometry favors imaging of the south aurora. Seven orbits of WFPC2 auroral investigations in cycles 4 and 5 indicate that most of Saturn's auroral energy is radiated from the morning sector in both polar regions, peaking near dawn, and that intensities are variable on 10-minute time scales. This suggests that magnetosphere-solar wind interactions play a dominant role in powering the auroral emissions. In addition, a correlation between the intensity of auroral emissions and the passage of a narrow range of magnetic longitudes through local time and was observed by Voyager in 1980-1, but has not been observed by WFPC2 because previous observations covered only a fraction of Saturn's rotation period. Due to a +/-7 second uncertainty in the Voyager- determined rotation period for Saturn, it is no longer possible to predict the CML of peak Saturn auroral activity. Observations covering an entire 10.66-hour rotation period are required to discriminate between the possible physical mechanisms that power the aurora. ------------------------------------------------------------------------------------ 6854( 21) - 11/05/97 17:00 - [ 2] Observations Description ------------------------ We will perform observations of Saturn with STIS/FUV MAMA in its imaging modes, to image the auroral and airglow emissions from the H2 Lyman and Werner band systems and emission from the H Ly alpha line. In order to discriminate between local-time and longitude-dependent components in Saturn's aurora, the first observing sequence consists of 3 orbits separated by gaps of one orbit each, all within a single 5-orbit observing opportunity for STIS MAMA detectors, in order to get adequate coverage of one full Saturn rotation. Thus, we will observe Saturn in three visits covering a single Saturn rotation, to measure the spatial extent and variability of the auroral emissions, then follow up with STIS imaging and spectroscopy at two later epochs. The following geometry constraints are needed: 1. The image sequence should be taken close to opposition to minimize the geocoronal H Lyman alpha background and maximize the size of the disk. 2. STIS MAMA operations are restricted to five consecutive SAA-free orbits per day. Given this 5-orbit window, the first three Saturn visits are to be scheduled in alternate orbits (ie. orbits 1, 3, and 5). Otherwise, no constraints are placed on Saturn longitude during the first observing sequence. 3. In visits 4 and 5, Saturn's central meridian longitudes are constrained to a range of longitudes to be determined from analysis of the data from visits 1, 3, and 5. 4. STIS spectra in visits 4 and 5 will be taken with the long slit aligned roughly N-S over the morning sector of Saturn's south polar auroral zone.. Real Time Justification ----------------------- Not Applicable Calibration Justification ------------------------- None Additional Comments ------------------- Visit 05 has an orient constraint to place the STIS slit parallel to the central meridian of Saturn. ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: ------------------------------------------------------------------------------------ 6854( 21) - 11/05/97 17:00 - [ 3] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: SAT-AUR ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=SATURN | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = -0.6+/-0.5 | F-LINE(1400)=1+/-1e-14 | W-LINE(1400)=420 | F-CONT(1800)=4+/-5e-13 | SIZE=16+/-13 | F-CONT(5500)=7.8+/-5e-12 | SIZE=1.1 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: SAT-AUR-CML ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = SATURN,CML OF SATURN FROM EARTH | BETWEEN 85 115 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = -0.6+/-0.5 | F-LINE(1400)=1+/-1e-14 | W-LINE(1400)=420 | F-CONT(1800)=4+/-5e-13 | SIZE=16+/-13 | F-CONT(5500)=7.8+/-5e-12 | SIZE=1.1 | | ------------------------------------------------------------------------------------------------------------------------------------ 6854( 21) - 11/05/97 17:00 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: TETHYS ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE TETHYS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=SATURN | TETHYS | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 10.2+/-0.5 | | ------------------------------------------------------------------------------------------------------------------------------------ 6854( 21) - 11/05/97 17:00 - [ 5] Visit: 01 Visit Priority: Visit Requirements: SCHED 70%; BETWEEN 22-SEP-1997 AND 01-NOV-1997; GROUP 01-03 WITHIN 432M On Hold Comments: Additional Comments: Visits 01-03 execute within a period of 5 consecutive orbits as (01-xx-02- xx-03). Gaps are needed to increase the range of CML covered. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 SAT-AUR STIS/F TIME-TA F25SRF2 MIRROR BUFFER-TIME=2000 1 1000 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 12 SAT-AUR STIS/F TIME-TA 25MAMA MIRROR BUFFER-TIME=250 1 1000 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 6854( 21) - 11/05/97 17:00 - [ 6] Visit: 02 Visit Priority: Visit Requirements: SCHED 70% On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 21 SAT-AUR STIS/F TIME-TA F25SRF2 MIRROR BUFFER-TIME=2000 1 1000 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 22 SAT-AUR STIS/F TIME-TA 25MAMA MIRROR BUFFER-TIME=250 1 1000 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 6854( 21) - 11/05/97 17:00 - [ 7] Visit: 03 Visit Priority: Visit Requirements: SCHED 70% On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 31 SAT-AUR STIS/F TIME-TA F25SRF2 MIRROR BUFFER-TIME=2000 1 1000 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 32 SAT-AUR STIS/F TIME-TA 25MAMA MIRROR BUFFER-TIME=250 1 1000 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 6854( 21) - 11/05/97 17:00 - [ 8] Visit: 04 Visit Priority: Visit Requirements: SCHED 70%; Between 20-Nov-1997:00:00:00 and 21-Nov-1997:08:00:00; Between 21-Nov-1997:10:00:00 and 22-Nov-1997:00:00:00; On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 41 SAT-AUR-CML STIS/F TIME-TA F25SRF2 MIRROR BUFFER-TIME=1000 1 1000 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 42 SAT-AUR-CML STIS/F TIME-TA 25MAMA MIRROR BUFFER-TIME=100 1 1000 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 6854( 21) - 11/05/97 17:00 - [ 9] Visit: 05 Visit Priority: Visit Requirements: SCHED 70%; ORIENT 48D TO 48D; Between 5-Dec-1997:03:00:00 and 5-Dec- 1997:06:00:00 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 51 TETHYS STIS/C ACQ F28X50L MIRROR ACQTYPE= POINT 1 0.1 S ONBOARD ACQ FOR 52-53 CD P ------------------------------------------------------------------------------------------------------------------------------------ 52 SAT-AUR-CML STIS/F TIME-TA 52X0.5 G140L 1425 BUFFER-TIME=1000,WAVECAL=NO 1 1000 S POS TARG -2.0,0.0 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 53 SAT-AUR-CML STIS/F TIME-TA 25MAMA MIRROR BUFFER-TIME=100 1 600 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 6854( 21) - 11/05/97 17:00 - [ 10] Summary Form for Proposal 6854 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/FUV-MAMA STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes TIME-TAG ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=2000 BUFFER-TIME=250 BUFFER-TIME=1000 BUFFER-TIME=100 ACQTYPE= POINT WAVECAL=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GTO/WF2 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 70%; BETWEEN 22-SEP-1997 AND 01-NOV-1997; GROUP 01-03 WITHIN 432M SCHED 70% SCHED 70%; Between 20-Nov-1997 00 00 00 and 21-Nov-1997 08 00 00; Between 21-Nov-1997 10 00 00 and 22-Nov-1997 00 00 00; SCHED 70%; ORIENT 48D TO 48D; Between 5-Dec-1997 03 00 00 and 5-Dec-1997 06 00 00 ONBOARD ACQ FOR 52-53 POS TARG -2.0,0.0 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names SAT-AUR SAT-AUR-CML TETHYS ------------------------------------------------------------------------------------------------------------------------------------