6215( 3) - 08/04/95 15:37 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6215 Version: 3 Check-in Date: ********** 1.Proposal Title: SATURN'S AURORA AND AIRGLOW ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle SOLAR SYSTEM,OUTER PL GTO/WF2 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: John Trauger Jet Propulsion Laboratory CoI: Richard Griffiths Johns Hopkins University N CoI: Jeff Hester Arizona State University N CoI: Jon Holtzman Lowell Observatory N CoI: John Clarke University of Michigan N CoI: Jeremy Mould Mt. Stromlo and Siding Spring Observatory N CoI: Gilda Ballester University of Michigan N CoI: James Westphal California Institute of Technology N CoI: Karl Stapelfeldt Jet Propulsion Laboratory N CoI: David Crisp Jet Propulsion Laboratory N CoI: Christopher Burrows Space Telescope Science Institute N CoI: John Hoessel University of Wisconsin-Madison N CoI: John Gallagher University of Wisconsin-Madison N ------------------------------------------------------------------------------------ 6. Abstract This proposal is for far-UV imaging of Saturn's auroral emissions in the H Ly alpha (1216 Angstrom) and H_2 Lyman and Werner bands (900-1650 Angstrom) with WFPC2. In cycle 5 the geometry will be appropriate to image the south aurora for the first time. We will observe Saturn in two separate visits, to measure variations in the morphology of the auroral emissions expected to arise from changes in the driving mechanisms, such as with respect to magnetic longitude, intrinsic temporal variations, Saturnian satellites or solar wind parameters. ------------------------------------------------------------------------------------ 6215( 3) - 08/04/95 15:37 - [ 2] Observations Description ------------------------ We will perform observations of Saturn in the far-UV with WFPC2, using F160W and F160W+F130LP, to image the auroral and airglow emissions from the H_2 Lyman and Werner band systems and emission from the H Ly alpha line. Short images will be taken with F218W to measure the Rayleigh scattered sunlight by the planet (providing better signal than with the F160W+F165LP combination at only slightly longer wavelength), and for pointing information. Two consecutive orbits will be dedicated to each visit, and a total of 2 visits will be made. The following geometry constraints are needed: - For each visit, the range of Saturn's (System III) CML as seen from Earth should be between 110 and 220 deg, to observe two particular longitude regions, and be able to measure temporal versus longitudinal variations by comparison with the Cycle 4 images. - Dione should be between orbital longitudes 145 and 215 deg, so that its footprint is near the CML, where it can be resolved with WFPC2. - The two visits should be separated by an integral number of ~0.5 onths to have a different side of the Sun (and thus possibly solar wind characteristics) facing Saturn. - The images should be taken close to opposition to minimize the geocoronal H Lyman alpha background and maximize the size of the disk. Real Time Justification ----------------------- The observational constraints itemized above are necessary to sort out possible dependences of the emissions suggested by spacecraft data and by our Cycle 4 GTO images. The first two contraints limit the target availability to about once or twice every 3 days, but there should be plenty of opportunities in the 3-month window provided for the visits. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6215( 3) - 08/04/95 15:37 - [ 3] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = SATURN | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | WND FROM 15-JUL-1995 TO 15-NOV-1995, CML | OF SATURN FROM EARTH BETWEEN 100 220, | OLG OF DIONE BETWEEN 145 215, SEP OF | TITAN SATURN FROM EARTH GT 15" | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = -0.6 +/- 0.5 F-LINE(1400) = 1 +/- 1E-14 W- | | ------------------------------------------------------------------------------------------------------------------------------------ 6215( 3) - 08/04/95 15:37 - [ 4] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: The order of the 2 exposures per orbit is optimum for pre-opposition time, since the far-UV images (with spectral element F160BN15) at the beginning of each orbit should overlap dark time for the longest possible time. If the visit is made post-opposition, we request to reverse the order of the 2 exposures per orbit. That is, interchange 111 and 112, as well as 121 and 122. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 111 SATURN WFPC2 IMAGE WF3-FIX F218W ATD-GAIN = 7 CR 1 300S -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 112 SATURN WFPC2 IMAGE F160BN1 F160BN15 ATD-GAIN = 7 CR 1 1500S END ORBIT 5 -SPLIT = NO ------------------------------------------------------------------------------------------------------------------------------------ 121 SATURN WFPC2 IMAGE WF3-FIX F218W ATD-GAIN = 7 CR 1 500S -SPLIT = NO ------------------------------------------------------------------------------------------------------------------------------------ 122 SATURN WFPC2 IMAGE F160BN1 F160BN15, ATD-GAIN = 7 CR 1 1500S END ORBIT 5 F130LP -SPLIT = NO ------------------------------------------------------------------------------------------------------------------------------------ 6215( 3) - 08/04/95 15:37 - [ 5] Visit: 02 Visit Requirements: after 01 by 10d to 20d On Hold Comments: Additional Comments: Separate visits 01 and 02 by an integral number of ~0.5 months. As with visit 01, please reverse the order of the 2 exposures per orbit if the visit is made post-opposition. Ie, interchange 211 and 212, as well as 221 and 222. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 211 SATURN WFPC2 IMAGE WF3-FIX F218W ATD-GAIN = 7 CR 1 300S -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 212 SATURN WFPC2 IMAGE F160BN1 F160BN15 ATD-GAIN = 7 CR 1 1500S END ORBIT 5 -SPLIT = NO ------------------------------------------------------------------------------------------------------------------------------------ 221 SATURN WFPC2 IMAGE WF3-FIX F218W ATD-GAIN = 7 CR 1 500S -SPLIT = NO ------------------------------------------------------------------------------------------------------------------------------------ 222 SATURN WFPC2 IMAGE F160BN1 F160BN15, ATD-GAIN = 7 CR 1 1500S END ORBIT 5 F130LP -SPLIT = NO ------------------------------------------------------------------------------------------------------------------------------------ 6215( 3) - 08/04/95 15:37 - [ 6] Summary Form for Proposal 6215 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ATD-GAIN = 7 CR-SPLIT=NO ATD-GAIN = 7 CR-SPLIT = NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GTO/WF2 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM,OUTER PLANETS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements END ORBIT after 01 by 10d to 20d ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F218W F160BN15 F160BN15,F130LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names SATURN ------------------------------------------------------------------------------------------------------------------------------------