6806( 11) - 09/06/96 10:48 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6806 Version: 11 Check-in Date: 06-Sep-1996 10:44:16 1.Proposal Title: Saturn's Rings ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle SOLAR SYSTEM GO 0 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: RICHARD G. FRENCH WELLESLEY COLLEGE CoI: Jack Lissauer State University of New York at Stony N Brook CoI: Jeff Cuzzi NASA Ames Research Center N CoI: Luke Dones San Jose State University N ------------------------------------------------------------------------------------ 6. Abstract Saturn's rings are a unique dynamical laboratory and, more than a decade after Voyager, continue to present challenging problems which require additional data to attack. Making use of the capabilities of HST, and the changing geometry of the rings as seen from Earth orbit over the next seven years, we propose to address important outstanding problems such as the composition of the ring material (which is known to be radially variable on spatial scales down to hundreds of km), the ``filling factor" of the rings (which is a key constraint on their dynamical behavior), continuing controversy over the cause of the ``opposition brightening", transient gravitational instabilities (from their photometric signatures), azimuthal asymmetries in ring brightness, and the temporal variability of ``spokes" and other dynamically interesting regions. We propose to obtain a coherent set of images of the Saturnian ring system over the course of 1/4 Saturn year (7 Earth years) using filters UBVRI and methane with the PC chip of WFPC2. The rings will be imaged four times per year (at 0,0.6,2, and 6 degrees phase) using this filter set; exposures with two other filters designed to measure composition will augment our standard set as time allows. We will attempt to image the G ring with the PC in the V filter when the ring is at its lowest tilt angle. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our primary goal for Cycle 6 observations is to obtain high resolution (PC) images of both ansae of Saturn's rings over a broad range of colors at phase angles near 6,2,0.7 and ~0 degrees (corresponding to visits 1 through 4, respectively). The UBVRI exposures will be used to study color variations across the rings and for photometric modelling of the rings with varying illumination and viewing geometry. We want UBVRI coverage of BOTH ansae with the PC during every visit. The F785LP and F1042M exposures will be used for composition studies of the rings, and less frequent coverage is acceptable. The FQCH4 (8922A) filter will be used to suppress Saturn-shine onto the rings. A second goal is to observe Prometheus near greatest Eastern or Western elongation during at least one visit (and preferably during two widely-spaced visits), to determine its position and orbital characteristics. Recent HST/Ring Plane Crossing observations show that Prometheus now lags by 19 degrees of orbital longitude behind the JPL ephemeris position based on Voyager observations. The origin of this lag is not understood, and additional observations are needed to help sort out the dynamics at work. A third objective of our ring observations is to attempt to image the faint G Ring, which lies just outside the F Ring and the main ring system. It was detected during the November 1995 ring plane crossing HST observations, but in 2x2 binned WF images only. We hope to get two PC images of the ring when the tilt angle of the rings is near its minimum, which maximizes the slant path optical depth (and hence the contrast) of the rings. We will observe with the F555W filter, which gave the best SNR during the RPX observations. The desired image would provide higher spatial resolution of ring structure and information about the ring particle scattering properties. The orbital geometry of Saturn during Cycle 6 is such that there are two periods when the phase angle near each of our desired values of 6, 2, and 0.7 degrees, and either the pre- or post- opposition periods would give comparable science return. However, we STRONGLY PREFER that Visit 1 (the ~6 degree phase angle observations) occur EARLY in Cycle 6, rather than at the end. Early images will provide us with valuable information about how to optimize the observing strategy during the crucial low phase angle visits, when the opposition surge is most pronouced and when scheduling is most critical. The proposal as submitted results in scheduling diagnostics from the RPS2 software for Visits 3 and 4, since RPS2 claims that Saturn is not visible at opposition. We believe this is an RPS2 program error. After conversations with Dustin Manning, we have been given permission to submit our proposal as is, recognizing that the detailed schedule of exposures will require use of the actual STSCI planning software. Real Time Justification ----------------------- The primary time-critical events in our visits are that we observe Saturn at a number of fairly specific phase angles, and that whenever possible, the visits be timed so that Prometheus is not in front of or behind the planet. For the G Ring exposures, we would like to have a small satellite in the field to allow for accurate astrometry, but we want to avoid having large satellites nearby, since they would be badly overexposed, with large diffraction spikes which could contaminate our measurements of the faint ring. We have calculated times that are ideal but if these prove impossible to use, these constraints can be relaxed. For each visit, we summarize below the strategy behind our choices of exposures and targets. We have adopted a uniform numbering scheme for the exposures, as follows: Exposure #ijk, where i=visit number j=index for a set of exposures with the same pointing, but different filters k=filter index: 1 F336W U 2 F439W B 3 F555W V 4 F675W R 5 F814W I 6 F785LP for study of ring composition (=COMP#1) 7 F1042M for study of ring composition (=COMP#2) 8 FQCH4P15 (8922A) for suppression of Saturn shine (=CH4) Visit 1 - high phase angle (phase angle > 5.5 degrees), Prometheus/Pandora Conjunction ------------- ------------------------------------------------------------------------- Possible dates: BETWEEN 02-JUL-96:11:00:00 AND 10-JUL-96:11:00:00 <== STONGLY preferred or BETWEEN 29-Nov-96 AND 14-Jan-97 Rationale: This is the period of highest phase angle. It varies slowly during these periods, and this provides a wide window of visibility. We have imposed the requirement that Prometheus be near Eastern elongation during this visit so that we can get good positions for it, and also that Prometheus and Pandora be near conjunction (which occurs on 06-JUL-96:11:00:00). Exposures: Description: .............................................................................. 101-105 UBVRI of East Ansa of main rings, Prometheus near E. elongation 106 COMP#1 of E ansa 108 CH4 of E ansa 111-115 UBVRI of W ansa Options: If easier to schedule with Prometheus near W. elongation, we could switch E=>W and W=>E in all of the above exposures. Visit 2 - intermediate phase angle (phase angle ~2.0 degrees), G Ring attempt ------------------------------------------------- ------------------------------- Possible dates: BETWEEN 14-OCT-96:07:00:00 AND 16-Oct-96:09:00:00 or BETWEEN 14-OCT-96:00:00:00 AND 16-Oct-96:00:00:00 or BETWEEN 08-SEP-96:00:00:00 AND 10-SEP-96:00:00:00 Rationale: This is the period of intermediate phase angle. We strongly prefer the October period since the ring tilt angle is small, enhancing the contrast of the faint G Ring, and because the ring orientation is more closely parallel to the columns of the chip and diffraction effects should be less severe. Ideal times (7h - 9h 14 OCT) are for optimal satellite positions for G Ring exposures: major satellites visible in WF chip but away from G Ring, small satellite Epimetheus in G ring field for astrometry. Exposures: Description: .............................................................................. 201-205 UBVRI of East Ansa of main rings 211-215 UBVRI of W ansa 233 V of E ansa of G Ring Visit 3 - low phase angle coverage rings (phase angle ~0.7 degrees), Prometheus ---------------------------------------------------------- ---------------------- Possible dates: BETWEEN 01-OCT-96:00:00:00 AND 03-OCT- 96:00:00:00 or BETWEEN 21-SEP-96:00:00:00 AND 23-SEP-96:00:00:00 Rationale: This is the period of low phase angle. We prefer the later of the two periods because the ORIENT angle is more favorable for avoiding diffraction spike problems. Exposures: Description: .............................................................................. 301-305 UBVRI of East Ansa of main rings, Prometheus near E elong. 306 COMP#2 of E ansa 308 CH4 of E ansa 311-315 UBVRI of W ansa Visit 4 - minimum phase angle (~0.2 degrees), G Ring attempt ------------------------------------------ -------------------------------------- Possible dates: BETWEEN 26-SEP- 96:13:00:00 AND 26-SEP-96:18:00:00 or BETWEEN 26-SEP-96:00:00:00 AND 28-SEP- 96:00:00:00 Rationale: This is the period of minimum phase angle during this Cycle. Observations during this period are highly desirable to characterize the opposition surge in brightness near zero phase angle. 13h-18h on 26 SEP gives optimal satellite positions for G Ring observations (Large satellites away from G Ring but visible on WF chip, Epimetheus in G ring field. Exposures: Description: .............................................................................. 401-405 UBVRI of East Ansa of main rings 411-415 UBVRI of W ansa 433 V of E ansa of G Ring Calibration Justification ------------------------- We require no additional calibration exposures. We will be using the standard UBVRI filter set, the FQCH4P15 (8922A) filter, and F785LP and F1042M. We assume that the UBVRI and CH4 filters have been extensively calibrated, and that the F785LP and F1042M filters are sufficiently well understood not to require additional calibration. If major satellites are in the field, they can be used as local calibrators. The inclination of the rings to the line of sight is sufficiently large (and the exposures sufficiently short) that we do not expect scattered light from the satellites to contaminate our view of the rings (unlike the situation during ring plane crossing). Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6806( 11) - 09/06/96 10:48 - [ 1] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: SATURN-EAST-ANSA ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: RING SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=SATURN | TYPE=TORUS,LONG=270,LAT=0,RAD=70000,POLE | _LAT=+90 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 7.3 | Eastern ansa of Saturn rings B-V = 0.9 | centered on inner C Ring. This | centering insures that entire ring | ansa and most of planet will be | visible in a full PC frame, | independent of the orientation | angle. This is important, since near | zero phase angle, the U3 direction | changes rapidly. | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: SATURN-WEST-ANSA ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: RING SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=SATURN | TYPE=TORUS,LONG=90,LAT=0,RAD=70000,POLE_ | LAT=+90 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 7.3 | Western ansa of Saturn rings B-V = 0.9 | centered on inner C Ring. This | centering insures that entire ring | ansa and most of planet will be | visible in a full PC frame, | independent of the orientation | angle. This is important, since near | zero phase angle, the U3 direction | changes rapidly. | ------------------------------------------------------------------------------------------------------------------------------------ 6806( 11) - 09/06/96 10:48 - [ 2] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 4 | TARGET NAME: SATURN-EAST-ANSA-PROMETHEUS ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: RING SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=SATURN | TYPE=TORUS,LONG=270,LAT=0,RAD=70000,POLE | _LAT=+90 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF PROMETHEUS BETWEEN 60 140, SEP OF | PANDORA SATURN FROM EARTH GT 15" | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 7.3 | E ansa of rings centered on inner C B-V = 0.9 | Ring. Prometheus near Eastern | elongation. OLG limits allow for lag | of Prometheus by 19 degrees from | standard ephemeris, and insure it is | at least 90,000 km in the sky plane | from the center of Saturn. SEP puts | both Pandora, Prometheus in field. | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 6 | TARGET NAME: SATURN-EAST-ANSA-CH4 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: RING SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=SATURN | TYPE=TORUS,LONG=270,LAT=0,RAD=107000,POL | E_LAT=+90 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 7.3 | Eastern ansa of Saturn rings B-V = 0.9 | centered on the mid-ring region. | This centering insures that entire | ring ansa will be visible in the | unvignetted region of the PC frame | in the FQCH4N filter, independent of | the orientation angle. This is | important, since near zero phase | angle, the U3 direction changes | rapidly. | 6806( 11) - 09/06/96 10:48 - [ 3] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 8 | TARGET NAME: SATURN-EAST-ANSA-G-RING ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: RING SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=SATURN | TYPE=TORUS,LONG=270,LAT=0,RAD=168000,POL | E_LAT=+90 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | SEP OF MIMAS SATURN-EAST-ANSA-G-RING | FROM EARTH GT 15", SEP OF ENCELADUS | SATURN-EAST-ANSA-G-RING FROM EARTH GT | 15", SEP OF TETHYS SATURN-EAST-ANSA-G- | RING FROM EARTH GT 15", SEP OF DIONE | SATURN-EAST-ANSA-G-RING FROM EARTH GT | 15", SEP OF RHEA SATURN-EAST-ANSA-G-RING | FROM EARTH GT 15", SEP OF TITAN SATURN- | EAST-ANSA-G-RING FROM EARTH GT 15", SEP | OF IAPETUS SATURN-EAST-ANSA-G-RING FROM | EARTH GT 15" | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 7.3 | Eastern ansa of Saturn rings B-V = 0.9 | centered on G Ring. Window keeps | major satellites out of nearby field | of target so diffraction and | blooming won't interfere. Flux | listed is for A Ring. Used for Visit | 2. | ------------------------------------------------------------------------------------------------------------------------------------ 6806( 11) - 09/06/96 10:48 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 9 | TARGET NAME: SATURN-WEST-ANSA-G-RING ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: RING SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=SATURN | TYPE=TORUS,LONG=90,LAT=0,RAD=168000,POLE | _LAT=+90 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | SEP OF MIMAS SATURN-WEST-ANSA-G-RING | FROM EARTH GT 15", SEP OF DIONE SATURN- | WEST-ANSA-G-RING FROM EARTH GT 15", SEP | OF RHEA SATURN-WEST-ANSA-G-RING FROM | EARTH GT 15", SEP OF TITAN SATURN-WEST- | ANSA-G-RING FROM EARTH GT 15", SEP OF | IAPETUS SATURN-WEST-ANSA-G-RING FROM | EARTH GT 15" | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 7.3 | Western ansa of Saturn rings B-V = 0.9 | centered on G Ring. Window keeps | major satellites out of nearby field | of target so diffraction and | blooming won't interfere. Flux | listed is for A Ring. Used for Visit | 4. Enceladus and Tethys are off of | PC so SEP requirement commented out | for those satellites. | ------------------------------------------------------------------------------------------------------------------------------------ 6806( 11) - 09/06/96 10:48 - [ 5] Visit: 01 Visit Requirements: BETWEEN 30-NOV-96 AND 15-JAN-97 On Hold Comments: Additional Comments: phase angle >5.5 deg, Pandora-Prometheus conjunction. (BETWEEN 30-NOV-96 AND 15-JAN-97 gives same phase angle coverage but is much less desirable since we want an early series of images to be able to optimize our near zero -phase vists.) If it is easier to schedule Prometheus at elongation on the West ansa, replace EAST by WEST within Target_Names for 101-108, and WEST by EAST in 111-118. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 101 SATURN-EAST WFPC2 IMAGE PC1-FIX F336W 3344 1 35 S POS TARG 0,0 -ANSA-PROME THEUS Comments: U filter. ------------------------------------------------------------------------------------------------------------------------------------ 102 SATURN-EAST WFPC2 IMAGE PC1-FIX F439W 1 4 S SAME POS AS 101 -ANSA-PROME THEUS Comments: B filter ------------------------------------------------------------------------------------------------------------------------------------ 103 SATURN-EAST WFPC2 IMAGE PC1-FIX F555W 1 .3 S SAME POS AS 101 -ANSA-PROME THEUS Comments: V filter ------------------------------------------------------------------------------------------------------------------------------------ 104 SATURN-EAST WFPC2 IMAGE PC1-FIX F675W 1 .3 S SAME POS AS 101 -ANSA-PROME THEUS Comments: R filter ------------------------------------------------------------------------------------------------------------------------------------ 105 SATURN-EAST WFPC2 IMAGE PC1-FIX F814W 1 0.3 S SAME POS AS 101 -ANSA-PROME THEUS Comments: I filter. Will compare this with exposure 108 to quantify Saturn-shine. ------------------------------------------------------------------------------------------------------------------------------------ 106 SATURN-EAST WFPC2 IMAGE PC1-FIX F785LP 1 0.8 S SAME POS AS 101 -ANSA-PROME THEUS Comments: Filter selected for composition studies of rings. ------------------------------------------------------------------------------------------------------------------------------------ 108 SATURN-EAST WFPC2 IMAGE FQCH4P1 FQCH4P15 8922 1 20 S POS TARG 0,0 -ANSA-CH4 5 Comments: CH4 filter to decrease Saturn shine on rings, to compare to I filter exposure. Centered on middle of rings because of vignetting across chip in this filter. ------------------------------------------------------------------------------------------------------------------------------------ 6806( 11) - 09/06/96 10:48 - [ 6] 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-WEST WFPC2 IMAGE PC1-FIX F336W 3344 1 35 S POS TARG 0,0 -ANSA Comments: U filter. ------------------------------------------------------------------------------------------------------------------------------------ 112 SATURN-WEST WFPC2 IMAGE PC1-FIX F439W 1 4 S SAME POS AS 111 -ANSA Comments: B filter. ------------------------------------------------------------------------------------------------------------------------------------ 113 SATURN-WEST WFPC2 IMAGE PC1-FIX F555W 1 0.3 S SAME POS AS 111 -ANSA Comments: V filter. ------------------------------------------------------------------------------------------------------------------------------------ 6806( 11) - 09/06/96 10:48 - [ 7] Visit: 02 Visit Requirements: BETWEEN 13-OCT-96:07:00:00 AND 17-Oct-96:09:00:00 ORIENT 48D TO 68D On Hold Comments: Additional Comments: phase angle ~2 deg. Tight time constraints are for optimal satellite locations (Epimetheus in G Ring field, large satellites on WF4 chip for astrometry). If unschedulable, can relax time constraints as follows: BETWEEN 14-OCT-96:00:00:00 AND 16-Oct-96:00:00:00 BETWEEN 08-SEP-96:00:00:00 AND 10-SEP-96:00:00:00 give same phase angle coverage. Prometheus coverage desirable but not mandatory. We compute the nominal ORIENT to be 58D for this visit, but since this is near opposition, we list this requirement for insurance since the POS TARG we compute for the G Ring exposure assumes ORIENT=58D Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 201 SATURN-EAST WFPC2 IMAGE PC1-FIX F336W 3344 1 35 S POS TARG 0,0 -ANSA Comments: U filter. ------------------------------------------------------------------------------------------------------------------------------------ 202 SATURN-EAST WFPC2 IMAGE PC1-FIX F439W 1 4 S SAME POS AS 201 -ANSA Comments: B filter ------------------------------------------------------------------------------------------------------------------------------------ 203 SATURN-EAST WFPC2 IMAGE PC1-FIX F555W 1 0.3 S SAME POS AS 201 -ANSA Comments: V filter ------------------------------------------------------------------------------------------------------------------------------------ 204 SATURN-EAST WFPC2 IMAGE PC1-FIX F675W 1 0.3 S SAME POS AS 201 -ANSA Comments: R filter ------------------------------------------------------------------------------------------------------------------------------------ 205 SATURN-EAST WFPC2 IMAGE PC1-FIX F814W 1 0.3 S SAME POS AS 201 -ANSA Comments: I filter. Will compare this with exposure 208 to quantify Saturn-shine. ------------------------------------------------------------------------------------------------------------------------------------ 211 SATURN-WEST WFPC2 IMAGE PC1-FIX F336W 3344 1 35 S POS TARG 0,0 -ANSA Comments: U filter. ------------------------------------------------------------------------------------------------------------------------------------ 212 SATURN-WEST WFPC2 IMAGE PC1-FIX F439W 1 4 S SAME POS AS 211 -ANSA Comments: B filter. ------------------------------------------------------------------------------------------------------------------------------------ 213 SATURN-WEST WFPC2 IMAGE PC1-FIX F555W 1 0.3 S SAME POS AS 211 -ANSA Comments: V filter. ------------------------------------------------------------------------------------------------------------------------------------ 6806( 11) - 09/06/96 10:48 - [ 8] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 233 SATURN-EAST WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO 1 400 S POS TARG 5.0,-14.0 -ANSA-G-RIN G Comments: G Ring, V filter. Put main rings into WF4. Reduce exposure time as needed to fit into visit. If ORIENT differs greatly from 58D, need to recompute this POS TARG. ------------------------------------------------------------------------------------------------------------------------------------ 6806( 11) - 09/06/96 10:48 - [ 9] Visit: 03 Visit Requirements: BETWEEN 30-SEP-96:00:00:00 AND 04-OCT-96:00:00:00 On Hold Comments: Additional Comments: phase angle ~0.6 deg. BETWEEN 21-SEP-96:00:00:00 AND 23-SEP-96:00:00:00 gives same phase angle coverage, but orientation of planet is less favorable since diffraction spikes will be parallel to rings. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 301 SATURN-EAST WFPC2 IMAGE PC1-FIX F336W 3344 1 35 S POS TARG 0,0 -ANSA-PROME THEUS Comments: U filter. ------------------------------------------------------------------------------------------------------------------------------------ 302 SATURN-EAST WFPC2 IMAGE PC1-FIX F439W 1 4 S SAME POS AS 301 -ANSA-PROME THEUS Comments: B filter ------------------------------------------------------------------------------------------------------------------------------------ 303 SATURN-EAST WFPC2 IMAGE PC1-FIX F555W 1 0.3 S SAME POS AS 301 -ANSA-PROME THEUS Comments: V filter ------------------------------------------------------------------------------------------------------------------------------------ 304 SATURN-EAST WFPC2 IMAGE PC1-FIX F675W 1 0.3 S SAME POS AS 301 -ANSA-PROME THEUS Comments: R filter ------------------------------------------------------------------------------------------------------------------------------------ 305 SATURN-EAST WFPC2 IMAGE PC1-FIX F814W 1 0.3 S SAME POS AS 301 -ANSA-PROME THEUS Comments: I filter. Will compare this with exposure 308 to quantify Saturn-shine. ------------------------------------------------------------------------------------------------------------------------------------ 306 SATURN-EAST WFPC2 IMAGE PC1-FIX F785LP 1 0.8 S SAME POS AS 301 -ANSA-PROME THEUS Comments: Filter selected for composition studies of rings. ------------------------------------------------------------------------------------------------------------------------------------ 311 SATURN-WEST WFPC2 IMAGE PC1-FIX F336W 3344 1 35 S POS TARG 0,0 -ANSA Comments: U filter. ------------------------------------------------------------------------------------------------------------------------------------ 312 SATURN-WEST WFPC2 IMAGE PC1-FIX F439W 1 4 S SAME POS AS 311 -ANSA Comments: B filter. ------------------------------------------------------------------------------------------------------------------------------------ 313 SATURN-WEST WFPC2 IMAGE PC1-FIX F555W 1 0.3 S SAME POS AS 311 -ANSA Comments: V filter. ------------------------------------------------------------------------------------------------------------------------------------ 6806( 11) - 09/06/96 10:48 - [ 10] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 314 SATURN-WEST WFPC2 IMAGE PC1-FIX F675W 1 0.3 S SAME POS AS 311 -ANSA Comments: R filter ------------------------------------------------------------------------------------------------------------------------------------ 315 SATURN-WEST WFPC2 IMAGE PC1-FIX F814W 1 0.3 S SAME POS AS 311 -ANSA Comments: I filter ------------------------------------------------------------------------------------------------------------------------------------ 6806( 11) - 09/06/96 10:48 - [ 11] Visit: 04 Visit Requirements: BETWEEN 26-SEP-96:00:00:00 AND 01-OCT-96:00:00:00 On Hold Comments: Additional Comments: opposition phase angle ~0.3 deg. ORIENT changes rapidly during the course of this visit because it is at opposition. We do not require a precise ORIENT value, but if the value is substantially different from this range, we need to recompute the POS TARG for exposure 433. If time constraints too tight to allow scheduling, relax constraints on satellite positions. Phase angle varies slowly during this pd: BETWEEN 26-SEP-96:00:00:00 AND 28-SEP- 96:00:00:00 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 401 SATURN-EAST WFPC2 IMAGE PC1-FIX F336W 3344 1 35 S POS TARG 0,0 -ANSA Comments: U filter. ------------------------------------------------------------------------------------------------------------------------------------ 402 SATURN-EAST WFPC2 IMAGE PC1-FIX F439W 1 4 S SAME POS AS 401 -ANSA Comments: B filter ------------------------------------------------------------------------------------------------------------------------------------ 403 SATURN-EAST WFPC2 IMAGE PC1-FIX F555W 1 0.3 S SAME POS AS 401 -ANSA Comments: V filter ------------------------------------------------------------------------------------------------------------------------------------ 404 SATURN-EAST WFPC2 IMAGE PC1-FIX F675W 1 0.3 S SAME POS AS 401 -ANSA Comments: R filter ------------------------------------------------------------------------------------------------------------------------------------ 405 SATURN-EAST WFPC2 IMAGE PC1-FIX F814W 1 0.3 S SAME POS AS 401 -ANSA Comments: I filter. Will compare this with exposure 408 to quantify Saturn-shine. ------------------------------------------------------------------------------------------------------------------------------------ 412 SATURN-WEST WFPC2 IMAGE PC1-FIX F439W 1 4 S -ANSA Comments: B filter. ------------------------------------------------------------------------------------------------------------------------------------ 413 SATURN-WEST WFPC2 IMAGE PC1-FIX F555W 1 0.3 S SAME POS AS 412 -ANSA Comments: V filter. ------------------------------------------------------------------------------------------------------------------------------------ 414 SATURN-WEST WFPC2 IMAGE PC1-FIX F675W 1 0.3 S SAME POS AS 412 -ANSA Comments: R filter ------------------------------------------------------------------------------------------------------------------------------------ 6806( 11) - 09/06/96 10:48 - [ 12] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 433 SATURN-WEST WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO 1 400 S POS TARG -13.5,0.0 -ANSA-G-RIN G Comments: G Ring, V filter. Put main rings into WF2. Reduce exposure time as needed to fit into visit. This POS TARG assumes ORIENT=340D. If ORIENT differs greatly from this, POS TARG will need to be recomputed. ------------------------------------------------------------------------------------------------------------------------------------ 6806( 11) - 09/06/96 10:48 - [ 13] Summary Form for Proposal 6806 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 30-NOV-96 AND 15-JAN-97 POS TARG 0,0 SAME POS AS 101 SAME POS AS 111 BETWEEN 13-OCT-96 07 00 00 AND 17-Oct-96 09 00 00 ORIENT 48D TO 68D SAME POS AS 201 SAME POS AS 211 POS TARG 5.0,-14.0 BETWEEN 30-SEP-96 00 00 00 AND 04-OCT-96 00 00 00 SAME POS AS 301 SAME POS AS 311 BETWEEN 26-SEP-96 00 00 00 AND 01-OCT-96 00 00 00 SAME POS AS 401 SAME POS AS 412 POS TARG -13.5,0.0 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F336W F439W F555W F675W F814W F785LP FQCH4P15 ------------------------------------------------------------------------------------------------------------------------------------ Target Names SATURN-EAST-ANSA-PROMETHEUS SATURN-EAST-ANSA-CH4 SATURN-WEST-ANSA SATURN-EAST-ANSA SATURN-EAST-ANSA-G-RING SATURN-WEST-ANSA-G-RING ------------------------------------------------------------------------------------------------------------------------------------