5823( 15) - 03/11/96 15:32 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5823 Version: 15 Check-in Date: 11-Mar-1996 15:16:34 1.Proposal Title: Uranus: Ringlet Kinematics and Atmospheric Structure ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Solar System GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Amanda S. Bosh Lowell Observatory CoI: Prof. James L. Elliot Massachusetts Institute of Technology N ------------------------------------------------------------------------------------ 6. Abstract On 1996 March 16 and 1996 April 10, Uranus and its rings will occult two bright SAO stars. With these events, we will obtain high spatial resolution information about Uranus' rings and atmosphere (greater resolution than is achievable from the ground, due to the greater S/N of HST observations). These observations will aid in refining ringlet kinematics and perhaps resolving the gap between fitted residuals and measurement errors; they will also be used to explore the latitudinal and temporal variation of Uranus' atmosphere. Because the atmosphere events occur at similar latitudes (exact locations await a more accurate HST orbit) and less than one month apart, these two events provide a unique opportunity to examine these questions. ------------------------------------------------------------------------------------ 5823( 15) - 03/11/96 15:32 - [ 2] Observations Description ------------------------ For each of U137 and U138, perform the following: (1) More than 2 hours before or after the occultation observations, obtain spectrum of star (U137, U138) with the G650L/RD element (to be used during the occultation observations). This determines the spectrum of the star for later use in data analysis. (2) At least one orbit before the start of the occultation observations, acquire an "offset- acquisition" star: one that is within 1.5 arcmin of the star to be occulted but further from Saturn and its rings than the target star. This offset acquisition technique has been successfully implemented before (GTO/HSP1081) to avoid problems with target acquisition in the bright scattered light background near Saturn. A suitable offset acquisition candidate will be chosen after ground-based astrometric frames are obtained and analyzed. (3) Blind offset to target star (U137, U138). Prior astrometry will have determined the relative positions of these two stars to better than 0.1 arcsec, assuring accurate placement of the target star in the science aperture. (4) Track on target star (U137, U138) while Uranus' rings and atmosphere (immersion) pass in front of it (1 orbit). (5) Track on target star (U137, U138) while Uranus' atmosphere and rings (emersion) pass in front of it (1 orbit). (6) Obtain spectra of Uranian atmosphere (near occultation latitudes) and rings. These observations establish the spectra of Uranus' atmosphere and rings separately, without any stellar component. These will be used in later analyses. Cycle 5: Primary Orbits: 10 Exposures: 10 Real Time Justification ----------------------- Time-critical: stellar occultations by solar system bodies are inherently time- critical observations. They occur at a particular time, determined by the planetary ephemeris and star position; therefore, no other dates/times are acceptable. We plan to apply for observing time at a ground-based station. While the S/N and resolution from such a site will be greatly inferior to that from the HST, additional observations will aid in constraining the geometry of the event (determining the ephemeris offsets f_0, g_0 are a crucial part of the analysis), and may also provide additional data points for studying ringlet kinematics. We will also provide ground-based astrometry prior to the event. With this astrometry we will locate offset acquisition targets and determine their positions relative to U137/U138 with an accuracy of better than 0.1 arcsec. We will also use this astrometry to refine the predicted times of feature events. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 5823( 15) - 03/11/96 15:32 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5823( 15) - 03/11/96 15:32 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 U137 STAR RA=20H 23M 47.22S +/- 0.01S, J2000 V = 8.92+/-0.25 DEC=-19D 54' 25.5" +/- 0.1", B-V = 0.51+/-0.25 PLATE-ID=01D0 V-R = 0.51+/-0.25 Comments: Star position updated 2/15 by Storrs, to use GSC coordinates. 3 U138 STAR RA=20H 27M 06.694S +/- 0.01S, J2000 V = 10.17+/-0.01 DEC=-19D 43' 48.87" +/- 0.1" B-V = 1.13+/-0.01 V-R = 0.63+/-0.1 Comments: Star position will be updated >= 2 months before observation is performed. Contact: Amanda S. Bosh, Lowell Observatory. 5823( 15) - 03/11/96 15:32 - [ 5] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 5 | TARGET NAME: URANUS-ATMOS ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET URANUS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=URANUS | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 8.27+/-0.1 | Used for scan along apparent path of B-V = 0.56+/-0.1 | occulted star to obtain background | flux levels. | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 6 | TARGET NAME: TITANIA ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE TITANIA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=URANUS | STD=TITANIA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 13.7+/-0.1 | Offset acquisition target for B-V = 0.7+/-0.1 | Uranus. | ------------------------------------------------------------------------------------------------------------------------------------ 5823( 15) - 03/11/96 15:32 - [ 6] Visit: 01 Visit Requirements: PCS MODE Fine GROUP 1-3 WITHIN 4D BETWEEN 16-MAR-96:15:21:00 AND 16-MAR- 96:15:23:00 AFTER 2 BY 2D On Hold Comments: Additional Comments: OCC, U137. Fine lock if possible; if not, coarse track is acceptable. Acquire U137-OFFSET, then blind offset to U137. Occultation start times will change after astrometry is obtained. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 30 U137 FOS/RD RAPID 1.0 G650L READ-TIME = 1 1019.92 END ORBIT USE OFFSET U137 0.122,SUB-STEP = 1,COMB = NO,STEP-TIME = 0.1 Comments: IGNORE SAA. Can split exposure across SAA. AT 16-MAR-96:14:53:30. USE DIODES 40-239 ONLY. Wavelength range was calculated using params in Table 2 of CAL/FOS-054. ------------------------------------------------------------------------------------------------------------------------------------ 5823( 15) - 03/11/96 15:32 - [ 7] Visit: 02 Visit Requirements: PCS MODE Fine On Hold Comments: Additional Comments: STAR-SPECTRA, U137. Fine lock if possible; if not, coarse track is acceptable. Get spectrum of occulted star when it is away from Uranus. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 50 U137 FOS/RD ACQ/PEA 4.3 G650L SCAN-STEP-Y = 1 1.0S ONBOARD ACQ FOR 60 K 1.23,SEARCH- SIZE-X = 1,SEARCH-SIZE-Y = 3 Comments: Time_per_exposure should be 1S. Do not execute within +/- 2H of Visit 1. ------------------------------------------------------------------------------------------------------------------------------------ 60 U137 FOS/RD ACQ/PEA 1.0 G650L SCAN-STEP-X = 1 1.0S ONBOARD ACQ FOR 70 K 0.61,SCAN-STEP- Y = 0.61,SEARCH -SIZE-X = 6,SEARCH-SIZE-Y Comments: Time_per_exposure should be 1.0S. = 2 ------------------------------------------------------------------------------------------------------------------------------------ 70 U137 FOS/RD ACQ/PEA 0.5 G650L SCAN-STEP-X = 1 1.0S ONBOARD ACQ FOR 80-90 SAVE OFFSET U137 K 0.29,SCAN-STEP- Y = 0.29,SEARCH -SIZE-X = 3,SEARCH-SIZE-Y Comments: Time_per_exposure should be 1.0S. Using Peak = 3 acquisitions to achieve sigma = 0.1" pointing accuracy (sequence A+B1+C1 from CAL/FOS-132). ------------------------------------------------------------------------------------------------------------------------------------ 80 U137 FOS/RD RAPID 1.0 G650L READ-TIME = 1 30.5S 0.122,SUB-STEP = 1,COMB = NO,STEP-TIME = 0.1 Comments: USE DIODES 40-239 ONLY. Wavelength range was calculated using params in Table 2 of CAL/FOS -054. Same parameters as occultation. ------------------------------------------------------------------------------------------------------------------------------------ 90 U137 FOS/RD ACCUM 1.0 G650L 1 5S Comments: Parameters set to optimize signal, calibration ability. ------------------------------------------------------------------------------------------------------------------------------------ 5823( 15) - 03/11/96 15:32 - [ 8] Visit: 03 Visit Requirements: PCS MODE Fine On Hold Comments: Additional Comments: BACK-SCANS, U137. Fine lock if possible; if not, coarse track is acceptable. Acquire Titania, then blind offset to Uranus. Scan parameters and Time_Per_Exposure will change with final geometric track prediction. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 100 TITANIA FOS/RD ACQ/BIN 4.3 MIRROR 1 1.06S ONBOARD ACQ FOR 110-120 ARY Comments: Do not execute within +/- 2H of Visit 1. Using Binary acquisition to achieve sigma = 0.12 arcsec pointing accuracy (sequence Z from CAL/FOS-132). ------------------------------------------------------------------------------------------------------------------------------------ 110 URANUS- FOS/RD RAPID 1.0 G650L READ-TIME = 1 132.98S SPATIAL SCAN 1 ATMOS 0.122,SUB-STEP = 1,COMB = NO,STEP-TIME = 0.1 Comments: USE DIODES 40-239 ONLY. Wavelength range was calculated using params in Table 2 of CAL/FOS -054. ------------------------------------------------------------------------------------------------------------------------------------ 120 URANUS- FOS/RD RAPID 1.0 G650L READ-TIME = 1 132.98S SPATIAL SCAN 2 ATMOS 0.122,SUB-STEP = 1,COMB = NO,STEP-TIME = 0.1 Comments: USE DIODES 40-239 ONLY. Wavelength range was calculated using params in Table 2 of CAL/FOS -054. ------------------------------------------------------------------------------------------------------------------------------------ 5823( 15) - 03/11/96 15:32 - [ 9] Visit: 04 Visit Requirements: PCS MODE Fine GROUP 4-6 WITHIN 75H BETWEEN 10-APR-96:10:40 AND 10-APR- 96:10:55 AFTER 5 BY 3D On Hold Comments: Additional Comments: OCC, U138. Fine lock if possible; if not, coarse track is acceptable. Acquire U138-OFFSET, then blind offset to U138. Occultation start times will change after astrometry is obtained. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 240 U138 FOS/RD RAPID 1.0 G650L READ-TIME = 1 1049.9S USE OFFSET U138 END ORBIT 0.122,SUB-STEP = 1,COMB = NO,STEP-TIME = 0.1 Comments: IGNORE SAA. Can split exposure across SAA. AT 10-APR-96:11:13. USE DIODES 40-239 ONLY. Wavelength range calculated using params in Table 2 of CAL/FOS-054. ------------------------------------------------------------------------------------------------------------------------------------ 250 U138 FOS/RD RAPID 1.0 G650L READ-TIME = 1 1049.9S USE OFFSET U138 0.122,SUB-STEP = 1,COMB = NO,STEP-TIME = 0.1 Comments: IGNORE SAA. Can split exposure across SAA. AT 10-APR-96:11:50:00. USE DIODES 40-239 ONLY. Wavelength range was calculated using params in Table 2 of CAL/FOS-054. ------------------------------------------------------------------------------------------------------------------------------------ 260 U138 FOS/RD RAPID 1.0 G650L READ-TIME = 1 1049.9S USE OFFSET U138 END ORBIT 0.122,SUB-STEP = 1,COMB = NO,STEP-TIME = 0.1 Comments: IGNORE SAA. Can split exposure across SAA. AT 10-APR-96:12:08:00. USE DIODES 40-239 ONLY. Wavelength range was calculated using params in Table 2 of CAL/FOS-054. ------------------------------------------------------------------------------------------------------------------------------------ 5823( 15) - 03/11/96 15:32 - [ 10] Visit: 05 Visit Requirements: PCS MODE Fine On Hold Comments: Additional Comments: STAR-SPECTRA. Fine lock if possible; if not, coarse track is acceptable. Get spectrum of occulted star when it is away from Uranus. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 270 U138 FOS/RD ACQ/PEA 4.3 G650L SCAN-STEP-Y = 1 1S ONBOARD ACQ FOR 280 K 1.23,SEARCH- SIZE-X = 1,SEARCH-SIZE-Y = 3 Comments: Time_per_exposure should be 0.007S. Do not execute within +/- 2H of Visit 1. ------------------------------------------------------------------------------------------------------------------------------------ 280 U138 FOS/RD ACQ/PEA 1.0 G650L SCAN-STEP-X = 1 1S ONBOARD ACQ FOR 290 K 0.61,SCAN-STEP- Y = 0.61,SEARCH -SIZE-X = 6,SEARCH-SIZE-Y Comments: Time_per_exposure should be 0.007S. = 2 ------------------------------------------------------------------------------------------------------------------------------------ 290 U138 FOS/RD ACQ/PEA 0.5 G650L SCAN-STEP-X = 1 1S ONBOARD ACQ FOR 300-310 SAVE OFFSET U138 K 0.29,SCAN-STEP- Y = 0.29,SEARCH -SIZE-X = 3,SEARCH-SIZE-Y Comments: Time_per_exposure should be 0.007S. Using = 3 Peak acquisitions to achieve sigma = 0.1" pointing accuracy (sequence A+B1+C1 from CAL/FOS-132). ------------------------------------------------------------------------------------------------------------------------------------ 300 U138 FOS/RD RAPID 1.0 G650L READ-TIME = 1 30.5S 0.122,SUB-STEP = 1,COMB = NO,STEP-TIME = 0.1 Comments: USE DIODES 40-239 ONLY. Wavelength range was calculated using params in Table 2 of CAL/FOS -054. Same parameters as occultation. ------------------------------------------------------------------------------------------------------------------------------------ 310 U138 FOS/RD ACCUM 1.0 G650L 1 50S Comments: Parameters set to optimize signal, calibration ability. ------------------------------------------------------------------------------------------------------------------------------------ 5823( 15) - 03/11/96 15:32 - [ 11] Visit: 06 Visit Requirements: PCS MODE Fine On Hold Comments: Additional Comments: BACK-SCANS. Fine lock if possible; if not, coarse track is acceptable. Acquire Titania, then blind offset to Uranus. Scan parameters and Time_Per_Exposure will change with final geometric track prediction. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 320 TITANIA FOS/RD ACQ/BIN 4.3 MIRROR 1 1.06S ONBOARD ACQ FOR 330-340 ARY Comments: Do not execute within +/- 2H of Visit 1. Using Binary acquisitions to achieve sigma = 0.12 arcsec pointing accuracy (sequence Z from CAL/FOS-132). ------------------------------------------------------------------------------------------------------------------------------------ 330 URANUS- FOS/RD RAPID 1.0 G650L READ-TIME = 1 132.98S SPATIAL SCAN 3 ATMOS 0.122,SUB-STEP = 1,COMB = NO,STEP-TIME = 0.1 Comments: USE DIODES 40-239 ONLY. Wavelength range was calculated using params in Table 2 of CAL/FOS -054. ------------------------------------------------------------------------------------------------------------------------------------ 340 URANUS- FOS/RD RAPID 1.0 G650L READ-TIME = 1 132.98S SPATIAL SCAN 4 ATMOS 0.122,SUB-STEP = 1,COMB = NO,STEP-TIME = 0.1 Comments: USE DIODES 40-239 ONLY. Wavelength range was calculated using params in Table 2 of CAL/FOS -054. ------------------------------------------------------------------------------------------------------------------------------------ 5823( 15) - 03/11/96 15:32 - [ 12] Scan Paramters Form ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 1 Exposure Logsheet lines: 9.110 FGS Scan: C Dwell Only: dwell points/line: 0 Seconds per dwell: 0.00 Scan width (arc-secs): 0.0000 Scan length (arc-secs): 10.0000 Angle between sides (degrees) 270.00 Number of lines: 1 Scan rate (arc-sec/sec): 0.0750 PA of first scan line (degrees) 65.500 Scan frame (CEL or S/C): CEL Length Offset (arc-sec): 5.4000 Width Offset (arc-sec): 0.5000 ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 2 Exposure Logsheet lines: 9.120 FGS Scan: C Dwell Only: dwell points/line: 0 Seconds per dwell: 0.00 Scan width (arc-secs): 1.0000 Scan length (arc-secs): 10.0000 Angle between sides (degrees) 90.00 Number of lines: 3 Scan rate (arc-sec/sec): 0.0750 PA of first scan line (degrees) 65.500 Scan frame (CEL or S/C): CEL Length Offset (arc-sec): 5.4000 Width Offset (arc-sec): 0 ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 3 Exposure Logsheet lines: 12.330 FGS Scan: C Dwell Only: dwell points/line: 0 Seconds per dwell: 0.00 Scan width (arc-secs): 0.0000 Scan length (arc-secs): 10.0000 Angle between sides (degrees) 90.00 Number of lines: 1 Scan rate (arc-sec/sec): 0.0750 PA of first scan line (degrees) 75.000 Scan frame (CEL or S/C): CEL Length Offset (arc-sec): 4.9200 Width Offset (arc-sec): 0.7800 ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 4 Exposure Logsheet lines: 12.340 FGS Scan: C Dwell Only: dwell points/line: 0 Seconds per dwell: 0.00 Scan width (arc-secs): 1.0000 Scan length (arc-secs): 10.0000 Angle between sides (degrees) 90.00 Number of lines: 3 Scan rate (arc-sec/sec): 0.0750 PA of first scan line (degrees) 75.000 Scan frame (CEL or S/C): CEL Length Offset (arc-sec): 4.9200 Width Offset (arc-sec): 1.2800 ------------------------------------------------------------------------------------------------------------------------------------ 5823( 15) - 03/11/96 15:32 - [ 13] Summary Form for Proposal 5823 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes RAPID ACQ/PEAK ACCUM ACQ/BINARY ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters READ-TIME = 0.122 SUB-STEP = 1 COMB = NO STEP-TIME = 0.1 SEARCH-SIZE-Y = 3 SEARCH-SIZE-Y = 2 SEARCH-SIZE-X = 3 SEARCH-SIZE-X = 1 SEARCH-SIZE-X = 6 SCAN-STEP-Y = 0.29 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Solar System ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE Fine GROUP 1-3 WITHIN 4D BETWEEN 16-MAR-96 15 21 00 AND 16-MAR-96 15 23 00 AFTER 2 BY 2D END ORBIT USE OFFSET U137 PCS MODE Fine ONBOARD ACQ FOR 60 ONBOARD ACQ FOR 70 ONBOARD ACQ FOR 80-90 SAVE OFFSET U137 ONBOARD ACQ FOR 110-120 SPATIAL SCAN 1 SPATIAL SCAN 2 PCS MODE Fine GROUP 4-6 WITHIN 75H BETWEEN 10-APR-96 10 40 AND 10-APR-96 10 55 AFTER 5 BY 3D USE OFFSET U138 END ORBIT USE OFFSET U138 ONBOARD ACQ FOR 280 ONBOARD ACQ FOR 290 ONBOARD ACQ FOR 300-310 SAVE OFFSET U138 ONBOARD ACQ FOR 330-340 SPATIAL SCAN 3 SPATIAL SCAN 4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G650L MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names U137 TITANIA URANUS-ATMOS U138 ------------------------------------------------------------------------------------------------------------------------------------