6030( 7) - 09/18/95 17:00 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6030 Version: 7 Check-in Date: ********** 1.Proposal Title: Clouds and Aerosols on Saturn and Uranus ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Solar System GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Martin Tomasko Lunar and Planetary Lab CoI: Dr. Erich Karkoschka Lunar and Planetary Lab N ------------------------------------------------------------------------------------ 6. Abstract Our goal is to determine the vertical and horizontal distributions, and the optical and microphysical properties, of aerosols and clouds in the atmospheres of the outer planets. This information is needed to understand the roles of aerosols in forcing atmospheric circulation and particle microphysics. To achieve these goals we propose to acquire WFPC2 images of Saturn and Uranus in the UV, visible, and near - IR methane and continuum regions. UV and blue images provide vertical sounding of the absorptive part of the aerosol opacity, critical for heat-balance studies, while the methane bands give information on the scattering part. The combination of the two provides an estimate of particle size from the wavelength dependence of the opacity. HST observations are critical because (1) UV images can only be obtained by HST, (2) the high resolution provided by HST is required for center-to-limb coverage, and (3) of existing space observations, only HST provides a suitable wide range of filters. Observations taken during Saturn's ring-plane crossing in 1995 permit superior imaging of both hemispheres, especially in methane bands. New observations of Uranus can take advantage of the improved geometry for center-to- limb observations. This proposal is similar to one originally selected for Cycle 1 (program number 2564) for the outer planets that had to be limited to Jupiter and Saturn due to the degraded performance of the original HST optics. ------------------------------------------------------------------------------------ 6030( 7) - 09/18/95 17:00 - [ 2] Observations Description ------------------------ Our analyses requires a series of images in continuum and methane band filters. We need three methane band filters: FQCH4N15 (619 nm), FQCH4N (727 nm), and FQCH4P15 (892 nm). For Uranus, we use four continuum filters: F336W, F467M, F673N, and F850LP (which gets most of its light from the 940 nm continuum region). For Saturn we also use the continuum filters F255W, F410M, and F588N, and we replace the F850LP by the F953N filter. The most important filters are repeated for Saturn, since Saturn shows some changes with time and longitude. For most of the filters we achieve 70 per cent of the saturation level with relatively short exposure times. For those exposures, the maximum exposure time is set equal to the desired exposure time, so they will not be lengthened in case more time is available as described in the Phase II Proposal Instructions. A few exposures are not close to saturation as indicated by a longer maximum duration. Saturn's rings fit into the PC1 aperture only for some orientations. The optimal orientation is described in the visit requirements. Because of the asymmetric field of view of the 892 nm methane filter, we specify an offset from the centered position (POS TARG). The offset for both of the orbits of visit #3 is slightly different so that CCD blemishes will not fall on the same area. Real Time Justification ----------------------- Our long exposures on Saturn in the strongest methane bands require the rings to be dark in order not to saturate the image. The earth-facing side of the rings is not illuminated from 22 May 1995 to 11 August 1995 and from 19 November 1995 to 12 February 1996. Additionally, starting near 10 November 1995, the solar illumination will be so shallow that the rings will be faint enough. We want to observe two interesting phases of the ring-plane crossings of this season. In visit #2, the sun will shine through the transparant rings yielding scattering information about the rings at higher spatial resolution than possible from the ground. In visit #3, the sun will illuminate the rings at an angle of 0.03 degrees, giving a very sensitive probe of non-planar ring features. Voyager observed some bending waves when the sun was illuminating the rings at an angle of a few degrees. The extremly shallow illumination on 18/19 November 1995 has prospects for discoveries of ring features. If we miss this opportunity, the next one will be on 24 January 2039. In October, 1994, HST observations yielded the first map of Titan's surface. With proper scheduling, our Saturn observations could be made when Titan is in the field. Our filter set is more complete than the filter used on Titan so far. Our F953N filter may probe the surface better than the F850LP filter which showed surface features of highest contrast so far. On the other hand, we have a poor orbital coverage with only two positions if the observation can be scheduled according to our visit requests. Thus, our data set would be complementary to the existing one. We will conduct spectrophotometry of Saturn and Uranus at the 1.5 m spectroscopic telescope at the European Southern Observatory on 6-10 July 1995. These observations will provide spectroscopic information at 1 nm resolution with relatively low spatial resolution, while the HST images will provide high spatial resolution at a few wavelengths sampling the spectrum. Such supplemental data sets have been proven to be very valuable in the past. For example, HST filter transmission curves can be convolved with the planetary spectrum for an accurate interpretation of the HST images. We prefer if one or two of our visits can be scheduled in July, 1995. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6030( 7) - 09/18/95 17:00 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6030( 7) - 09/18/95 17:00 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: URANUS ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET URANUS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = URANUS | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF URANUS BETWEEN 300 60 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 5.6 B-V = 0.6 U-B = 0.3 | Window requirement means within 2 | months of opposition. | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: SATURN-NO-RING ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = SATURN | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | WND FROM 22-MAY-95 TO 11-AUG-95 WND FROM | 10-NOV-95 TO 11-FEB-96 OLG OF TITAN | BETWEEN 174 183 SEP OF TITAN SATURN FROM | EARTH GT .5" | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 1.1 B-V = 1.1 U-B = 0.6 | The WND requirement is the time | period when Saturn's rings are so | dark that they will not saturate in | methane filter exposures. This is | essential as described in the | proposal. We request Titan in the | field of view (orbital longitude 174 | -183 degrees). This is not a | requirement. | ------------------------------------------------------------------------------------------------------------------------------------ 6030( 7) - 09/18/95 17:00 - [ 5] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: SATURN-DIM-RING ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = SATURN | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | WND FROM 22-MAY-95 TO 11-AUG-95 WND FROM | 10-NOV-95 TO 11-FEB-96 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 1.1 B-V = 1.1 U-B = 0.6 | The WND requirement is the time | period when Saturn's rings are so | dark that they will not saturate in | methane filter exposures. This is | essential as described in the | proposal. | ------------------------------------------------------------------------------------------------------------------------------------ 6030( 7) - 09/18/95 17:00 - [ 6] Visit: 01 Visit Requirements: BEFORE 25-JUL-95 On Hold Comments: Additional Comments: We request that this visit occurs within a few weeks of our observing run at the European Southern Observatory 6-10 July 1995 where we will aquire spectroscopic data of Uranus. In case of scheduling difficulties, the BEFORE request can be deleted. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 URANUS WFPC2 IMAGE FQCH4W4 F467M ATD-GAIN=15 1 8S MAX DUR 8S ------------------------------------------------------------------------------------------------------------------------------------ 12 URANUS WFPC2 IMAGE FQCH4W4 FQCH4N 7274 ATD-GAIN=15 1 160S MAX DUR 180S ------------------------------------------------------------------------------------------------------------------------------------ 13 URANUS WFPC2 IMAGE FQCH4P1 F336W ATD-GAIN=15 1 100S MAX DUR 120S 5 ------------------------------------------------------------------------------------------------------------------------------------ 14 URANUS WFPC2 IMAGE FQCH4P1 FQCH4N15 6211 ATD-GAIN=15 1 160S MAX DUR 230S 5 ------------------------------------------------------------------------------------------------------------------------------------ 15 URANUS WFPC2 IMAGE FQCH4P1 F673N ATD-GAIN=15 1 100S MAX DUR 100S 5 ------------------------------------------------------------------------------------------------------------------------------------ 16 URANUS WFPC2 IMAGE FQCH4P1 F850LP ATD-GAIN=15 1 100S MAX DUR 120S 5 ------------------------------------------------------------------------------------------------------------------------------------ 17 URANUS WFPC2 IMAGE FQCH4P1 FQCH4P15 8922 ATD-GAIN=7 1 500S MAX DUR 1500S 5 CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 6030( 7) - 09/18/95 17:00 - [ 7] Visit: 02 Visit Requirements: ORIENT 272D TO 276D BEFORE 12-AUG-95 On Hold Comments: Additional Comments: We request a position angle of the X-axis of the WFPC2 of 229 degrees within a few degrees. This orientation optimizes the location of Saturn's rings on the CCD. We request that this visit occurs within the first dark- ring period since we obtain spectroscopic data of Saturn at the European Southern Observatory during this period (6-10 July 1995). This is not a requirement. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 21 SATURN-NO- WFPC2 IMAGE WF4-FIX F255W ATD-GAIN=7 1 160S MAX DUR 300S POS TARG 13,-17 RING ------------------------------------------------------------------------------------------------------------------------------------ 22 SATURN-NO- WFPC2 IMAGE WF4-FIX FQCH4N 7274 ATD-GAIN=15 1 12S MAX DUR 12S POS TARG 13,-17 RING CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 23 SATURN-NO- WFPC2 IMAGE PC1-FIX F336W ATD-GAIN=15 1 70S MAX DUR 70S POS TARG -2,-1 RING ------------------------------------------------------------------------------------------------------------------------------------ 24 SATURN-NO- WFPC2 IMAGE PC1-FIX F467M ATD-GAIN=15 1 16S MAX DUR 16S POS TARG -2,-1 RING ------------------------------------------------------------------------------------------------------------------------------------ 25 SATURN-NO- WFPC2 IMAGE PC1-FIX FQCH4N15 6211 ATD-GAIN=15 1 30S MAX DUR 30S POS TARG -2,-1 RING ------------------------------------------------------------------------------------------------------------------------------------ 26 SATURN-NO- WFPC2 IMAGE PC1-FIX F673N ATD-GAIN=15 1 18S MAX DUR 18S POS TARG -2,-1 RING ------------------------------------------------------------------------------------------------------------------------------------ 27 SATURN-NO- WFPC2 IMAGE PC1-FIX F953N ATD-GAIN=15 1 100S MAX DUR 120S POS TARG -2,-1 RING ------------------------------------------------------------------------------------------------------------------------------------ 28 SATURN-NO- WFPC2 IMAGE PC1-FIX FQCH4P15 8922 ATD-GAIN=15 1 500S MAX DUR 700S POS TARG -2,-1 RING CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 6030( 7) - 09/18/95 17:00 - [ 8] Visit: 03 Visit Requirements: ORIENT 92D TO 96D BETWEEN 16-NOV-95:20:00 AND 17-NOV-95:13:00 On Hold Comments: Additional Comments: We request a position angle of the X-axis of the WFPC2 of 49 degrees within a few degrees. This orientation optimizes the location of Saturn's rings on the CCD. We request that this visit occurs at the beginning of the crossing of the solar disk through the ring plane of Saturn, yielding an extremely shallow illumination which makes non-planar ring features visible. The next day such a geometry is observable to HST is on 24 January 2039. In case of scheduling difficulties the start time of the requested period could be shifted half a day or one day later, which still would yield a quite shallow illumination. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 31 SATURN-DIM- WFPC2 IMAGE PC1-FIX F673N ATD-GAIN=15 1 18S MAX DUR 18S POS TARG -2,-2 RING ------------------------------------------------------------------------------------------------------------------------------------ 32 SATURN-DIM- WFPC2 IMAGE PC1-FIX F953N ATD-GAIN=15 1 100S MAX DUR 120S POS TARG -2,-2 RING ------------------------------------------------------------------------------------------------------------------------------------ 33 SATURN-DIM- WFPC2 IMAGE PC1-FIX FQCH4P15 8922 ATD-GAIN=15 1 400S MAX DUR 1200S POS TARG -2,-2 RING CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 34 SATURN-DIM- WFPC2 IMAGE PC1-FIX FQCH4P15 8922 ATD-GAIN=15 1 300S MAX DUR 400S POS TARG -2,-2 RING CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 35 SATURN-DIM- WFPC2 IMAGE WF4-FIX FQCH4N 7274 ATD-GAIN=15 1 23S MAX DUR 23S POS TARG 13,-17 RING CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 36 SATURN-DIM- WFPC2 IMAGE WF4-FIX FQCH4N 7274 ATD-GAIN=15 1 10S MAX DUR 10S POS TARG 13,-17 RING CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 37 SATURN-DIM- WFPC2 IMAGE WF4-FIX F255W ATD-GAIN=15 1 350S MAX DUR 350S POS TARG 13,-17 RING ------------------------------------------------------------------------------------------------------------------------------------ 41 SATURN-DIM- WFPC2 IMAGE PC1-FIX F336W ATD-GAIN=15 1 80S MAX DUR 80S POS TARG -2,-1 RING ------------------------------------------------------------------------------------------------------------------------------------ 42 SATURN-DIM- WFPC2 IMAGE PC1-FIX F410M ATD-GAIN=15 1 40S MAX DUR 60S POS TARG -2,-1 RING ------------------------------------------------------------------------------------------------------------------------------------ 43 SATURN-DIM- WFPC2 IMAGE PC1-FIX F467M ATD-GAIN=15 1 18S MAX DUR 18S POS TARG -2,-1 RING ------------------------------------------------------------------------------------------------------------------------------------ 44 SATURN-DIM- WFPC2 IMAGE PC1-FIX F588N ATD-GAIN=15 1 14S MAX DUR 14S POS TARG -2,-1 RING ------------------------------------------------------------------------------------------------------------------------------------ 45 SATURN-DIM- WFPC2 IMAGE PC1-FIX FQCH4N15 6211 ATD-GAIN=15 1 30S MAX DUR 30S POS TARG -2,-1 RING ------------------------------------------------------------------------------------------------------------------------------------ 46 SATURN-DIM- WFPC2 IMAGE PC1-FIX F673N ATD-GAIN=15 1 18S MAX DUR 18S POS TARG -2,-1 RING ------------------------------------------------------------------------------------------------------------------------------------ 6030( 7) - 09/18/95 17:00 - [ 9] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 47 SATURN-DIM- WFPC2 IMAGE PC1-FIX F953N ATD-GAIN=15 1 100S MAX DUR 120S POS TARG -2,-1 RING ------------------------------------------------------------------------------------------------------------------------------------ 48 SATURN-DIM- WFPC2 IMAGE PC1-FIX FQCH4P15 8922 ATD-GAIN=15 CR- 1 700S MAX DUR 1200S POS TARG -2,-1 RING SPLIT=NO CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 49 SATURN-DIM- WFPC2 IMAGE PC1-FIX FQCH4P15 8922 ATD-GAIN=15 1 160S MAX DUR 300S POS TARG -2,-1 RING CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 6030( 7) - 09/18/95 17:00 - [ 10] Summary Form for Proposal 6030 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ATD-GAIN=15 ATD-GAIN=7 CLOCKS=YES ATD-GAIN=7 ATD-GAIN=15 CLOCKS=YES ATD-GAIN=15 CR-SPLIT=NO CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Solar System ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BEFORE 25-JUL-95 MAX DUR 8S MAX DUR 180S MAX DUR 120S MAX DUR 230S MAX DUR 100S MAX DUR 1500S ORIENT 272D TO 276D BEFORE 12-AUG-95 MAX DUR 300S POS TARG 13,-17 MAX DUR 12S POS TARG 13,-17 MAX DUR 70S POS TARG -2,-1 MAX DUR 16S POS TARG -2,-1 MAX DUR 30S POS TARG -2,-1 MAX DUR 18S POS TARG -2,-1 MAX DUR 120S POS TARG -2,-1 MAX DUR 700S POS TARG -2,-1 ORIENT 92D TO 96D BETWEEN 16-NOV-95 20 00 AND 17-NOV-95 13 00 MAX DUR 18S POS TARG -2,-2 MAX DUR 120S POS TARG -2,-2 MAX DUR 1200S POS TARG -2,-2 MAX DUR 400S POS TARG -2,-2 MAX DUR 23S POS TARG 13,-17 MAX DUR 10S POS TARG 13,-17 MAX DUR 350S POS TARG 13,-17 MAX DUR 80S POS TARG -2,-1 MAX DUR 60S POS TARG -2,-1 MAX DUR 14S POS TARG -2,-1 MAX DUR 1200S POS TARG -2,-1 MAX DUR 300S POS TARG -2,-1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F467M FQCH4N F336W FQCH4N15 F673N F850LP FQCH4P15 F255W F953N F410M F588N ------------------------------------------------------------------------------------------------------------------------------------ Target Names URANUS SATURN-NO-RING SATURN-DIM-RING ------------------------------------------------------------------------------------------------------------------------------------