8224( 9) - 11/21/00 14:49 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8224 Version: 9 Check-in Date: 21-Nov-2000 14:48:59 1.Proposal Title: UV Imaging of Europa & Ganymede: Unveiling Satellite Aurora & Electrodynamical Interactions ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Melissa McGrath Space Telescope Science Institute CoI: Prof. Paul Feldman The Johns Hopkins University N CoI: Prof. Darrell Strobel The Johns Hopkins University N CoI: Mr. Kurt Retherford The Johns Hopkins University N CoI: Prof. Warren Moos The Johns Hopkins University N ------------------------------------------------------------------------------------ 5. Abstract We propose to obtain dispersed ultraviolet images of Europa and Ganymede using STIS to isolate atomic oxygen (1304 and 1356 Angstrom) and hydrogen (Lyman-Alpha) emissions, to study the interaction of the Jovian magnetosphere with the tenuous oxygen atmospheres of these icy satellites. Previous spectroscopic observations, from both HST (with GHRS) and Galileo, suggest the presence of polar aurorae on Ganymede whose geometry would be clearly delineated in these images. Europa is expected to show an oxygen emission morphology similar to that recently discovered on Io. ------------------------------------------------------------------------------------ 8224( 9) - 11/21/00 14:49 - [ 2] Observations Description ------------------------ We propose a simple set of STIS far-UV imaging observations of Europa and Ganymede using the G140L grating, which is sensitive to the O I 1304, CII 1335, and O I 1356 emissions detected previously from Europa and Ganymede. Observations of Europa spanning 5 consecutive HST orbits with Europa near western elongation maximizes the pathlength through the emitting region (irrespective of its morphology), and will cover a wide range in magnetic latitude, maximizing the ``wobble" of the magnetic field lines during the course of the observations. This observing geometry maximizes the chance of verifying the prediction that the Europa emissions have an Io-like morphology that is directly related to the magnetic field orientation. Observations of Ganymede will include one two-orbit visit to verify the Observations of Ganymede will isolate any bright, polar auroral emissions from either, or both, oxygen or hydrogen. Real Time Justification ----------------------- The Earth airglow emissions from \HI lyman-Alpha and O I 1304 create a significant sky background for STIS observations. For the STIS FUV-MAMA, filter F25SRF2, the typical High (day) values are more than two orders of magnitude higher than for the Dark (shadow) values (Table 6.4, p. 82 STIS Instrument Handbook). This is by far the dominant source of background for our observations, being ~3--5 orders of magnitude larger than either the detector dark current (Table 6.2, p. 79 STIS Instrument Handbook) or the zodiacal light. Performing the observations during High (day) would require significantly longer exposure times to achieve the same S/N. On this basis, we request that our observations be performed during shadow, i.e., near Jupiter opposition, to minimize the sky background contamination. This does not impose a severe scheduling constraint. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8224( 9) - 11/21/00 14:49 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: EUROPA ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE Europa ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=EUROPA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF EUROPA BETWEEN 240 300, OLG OF | JUPITER BETWEEN 330 20 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 5.3 | B-V = 0.87 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: GANYMEDE ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE Ganymede ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=GANYMEDE | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | CML OF JUPITER FROM EARTH BETWEEN 135 | 265, OLG OF GANYMEDE BETWEEN 70 110, OLG | OF JUPITER BETWEEN 310 40 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 4.6 | B-V = 0.83 | | ------------------------------------------------------------------------------------------------------------------------------------ 8224( 9) - 11/21/00 14:49 - [ 4] Visit: 01 Visit Priority: Visit Requirements: SCHED 100% between 5-Oct-1999:08:00:00 and 5-Oct-1999:16:00:00 between 16- Oct-1999:03:20:00 and 16-Oct-1999:11:30:00 between 13-Nov-1999:11:00:00 and 13-Nov-1999:19:30:00 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 ------------------------------------------------------------------------------------------------------------------------------------ 111 EUROPA STIS/C ACQ F28X50L MIRROR ACQTYPE=DIFFUSE,CHECKBOX=23, 1 0.1 S ONBOARD ACQ FOR 112 CD P DIFFUSE-CENTER=GEOMETRIC-CENTER ------------------------------------------------------------------------------------------------------------------------------------ 112 EUROPA STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=415 1 830 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 113 EUROPA STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=415 1 830 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 121 EUROPA STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=550 1 1100 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 122 EUROPA STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=550 1 1100 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 131 EUROPA STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=550 1 1100 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 132 EUROPA STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=550 1 1100 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 141 EUROPA STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=550 1 1100 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 142 EUROPA STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=550 1 1100 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 151 EUROPA STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=550 1 1100 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 152 EUROPA STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=550 1 1100 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8224( 9) - 11/21/00 14:49 - [ 5] Visit: 02 Visit Priority: Visit Requirements: SCHED 100% between 23-Dec-2000:03:26:45 and 23-Dec-2000:06:08:33 On Hold Comments: Additional Comments: The BETWEEN is the result of the BOP check. DO NOT MODIFY without CS approval. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 211 GANYMEDE STIS/C ACQ F28X50L MIRROR ACQTYPE=DIFFUSE, 1 0.1 S CD P DIFFUSE-CENTER=GEOMETRIC-CENTER, CHECKBOX=37 ------------------------------------------------------------------------------------------------------------------------------------ 212 GANYMEDE STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=370 1 740 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 213 GANYMEDE STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=370 1 740 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 214 GANYMEDE STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=550 1 1100 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 215 GANYMEDE STIS/F TIME-TA 52X2 G140L 1425 BUFFER-TIME=550 1 1100 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8224( 9) - 11/21/00 14:49 - [ 6] Summary Form for Proposal 8224 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=DIFFUSE CHECKBOX=23 DIFFUSE-CENTER=GEOMETRIC-CENTER BUFFER-TIME=415 BUFFER-TIME=550 CHECKBOX=37 BUFFER-TIME=370 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 100% between 5-Oct-1999 08 00 00 and 5-Oct-1999 16 00 00 between 16-Oct-1999 03 20 00 and 16-Oct-1999 11 30 00 between 13-Nov-1999 11 00 00 and 13-Nov-1999 19 30 00 ONBOARD ACQ FOR 112 SCHED 100% between 23-Dec-2000 03 26 45 and 23-Dec-2000 06 08 33 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names EUROPA GANYMEDE ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 ------------------------------------------------------------------------------------------------------------------------------------