6595( 11) - 06/18/96 11:18 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6595 Version: 11 Check-in Date: 18-Jun-1996 11:14:09 1.Proposal Title: Does Pluto Have a Haze Layer? ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle SOLAR SYSTEM GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: AMANDA BOSH LOWELL OBSERVATORY CoI: James L. Elliot Massachusetts Institute of Technology N ------------------------------------------------------------------------------------ 6. Abstract Pluto and its satellite Charon most likely formed in the solar nebula, and hence their composition can give us information about the early solar nebula. Furthermore, Pluto's tenuous, low-temperature atmosphere provides an interesting new regime for extending our understanding of atmospheric physics. From Earth, the only means of learning about these bodies at kilometer spatial resolution is through stellar occultations. We propose to observe two occultations by Pluto with the FOS in order to discriminate between the hazy and clear models for its atmosphere and to probe for variation in Pluto's atmospheric structure as it recedes from the sun. ------------------------------------------------------------------------------------ 6595( 11) - 06/18/96 11:18 - [ 2] Observations Description ------------------------ The following observing description applies to both Pluto occultations. (1) More than 4 days before the occultation observation, acquire star to be occulted, save offset for later use; also obtain spectrum of star with PRISM. This determines spectrum of the star for later use in data analysis. (3) Use pre-saved offset to reacquire star to be occulted. (4) Track on star while Pluto's atmosphere passes in front of it (1 orbit). The one atmosphere observation will last about 15 minutes, but because of uncertainties in the time of the occultation the observation should run for as long as possible in one orbit. 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 will provide ground-based astrometry prior to the event. With this astrometry we will locate an offset acquisition target and determine its position relative to the occulted star with an accuracy of better than 0.1 arcsec. We will also use this astrometry to refine the predicted impact time. We also plan to apply for observing time at ground-based stations to acquire the necessary multiple chords across Pluto. The S/N and resolution from such a site will be inferior to that from HST, but will be sufficient to constrain the impact parameter. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6595( 11) - 06/18/96 11:18 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 P31 STAR RA=16H 4M 01.961S +/- 0.01S, J2000 V = 15.7 DEC=-7D 23' 46.70" +/- 0.1" Comments: Star to be occulted by Pluto on 28-JUL-96:03:32 2 P32.02 STAR RA=16H 3M 51.266S +/- 0.01S, J2000 V = 17.1 DEC=-7D 36' 52.37" +/- 0.1" Comments: Star to be occulted by Pluto on 23-AUG-96:13:04 UT 6595( 11) - 06/18/96 11:18 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: PLUTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET PLUTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=PLUTO | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 13.52+/-0.05 | B-V = 0.80+/-0.05 | | ------------------------------------------------------------------------------------------------------------------------------------ 6595( 11) - 06/18/96 11:18 - [ 5] Visit: 01 Visit Requirements: PCS MODE Fine GROUP 1-3 WITHIN 10D On Hold Comments: Additional Comments: OCC-ACQ. Fine lock if possible; if not, coarse track is acceptable. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 P31 FOS/RD ACQ/BIN 4.3 MIRROR 1 7 S ONBOARD ACQ FOR 20 ARY ------------------------------------------------------------------------------------------------------------------------------------ 20 P31 FOS/RD ACQ/PEA 0.3 PRISM SCAN-STEP-X = 0.11,SCAN-STEP-Y = 1 7 S ONBOARD ACQ FOR 40 SAVE K 0.11,SEARCH-SIZE-X = 5, OFFSET PLOFF1 SEARCH-SIZE-Y = 5 Comments: Using Binary & Peak acquisitions to achieve 0.08" pointing accuracy (sequence Z+D2 from CAL/FOS-132). ------------------------------------------------------------------------------------------------------------------------------------ 40 P31 FOS/RD RAPID 1.0 PRISM 1485-89 READ-TIME = 0.231,SUB-STEP = 1, 1 120 S 50 COMB = NO,STEP-TIME = 0.2 Comments: USE DIODES 139-512 ONLY Get spectrum of occulted star when it is away from Pluto. Same parameters as occultation. ------------------------------------------------------------------------------------------------------------------------------------ 6595( 11) - 06/18/96 11:18 - [ 6] Visit: 02 Visit Requirements: PCS MODE Fine AFTER 1 BY 4D TO 9D BETWEEN 28-JUL-96:03:20 AND 28-JUL- 96:03:23 same orient as 1 On Hold Comments: Additional Comments: OCC. Fine lock if possible; if not, coarse track is acceptable. Predicted mid-tim 28-JUL-96:03:32, duration 5 minutes. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 50 P31 FOS/RD RAPID 1.0 PRISM 1485-89 READ-TIME = 0.231,SUB-STEP = 1, 1 1046 S END ORBIT USE OFFSET 50 COMB = NO,STEP-TIME = 0.2 PLOFF1 Comments: IGNORE SAA. Can split exposure across SAA. USE DIODES 139-512 ONLY ------------------------------------------------------------------------------------------------------------------------------------ 6595( 11) - 06/18/96 11:18 - [ 7] Visit: 03 Visit Requirements: PCS MODE Fine On Hold Comments: Additional Comments: Spectra of Pluto. Fine lock if possible; if not, coarse track is acceptable. Do not execute within +/- 45M of Visit 2. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 100 PLUTO FOS/RD ACQ/BIN 4.3 MIRROR 1 1.23 S ONBOARD ACQ FOR 110 ARY Comments: Do not execute within +/- 45M of Visit 2. ------------------------------------------------------------------------------------------------------------------------------------ 110 PLUTO FOS/RD ACQ/PEA 0.3 PRISM SCAN-STEP-X = 0.17,SCAN-STEP-Y = 1 1.24 S ONBOARD ACQ FOR 120-130 K 0.17,SEARCH-SIZE-X = 4, SEARCH-SIZE-Y = 4 Comments: Using Binary & Peak acquisitions to achieve 0.12" pointing accuracy (sequence Z+E1 from CAL/FOS-132). ------------------------------------------------------------------------------------------------------------------------------------ 120 PLUTO FOS/RD RAPID 1.0 PRISM READ-TIME = 0.231,SUB-STEP = 1, 1 66.99 S COMB = NO,STEP-TIME = 0.2 Comments: USE DIOES 139-512 ONLY (partial scattered light correction). ------------------------------------------------------------------------------------------------------------------------------------ 130 PLUTO FOS/RD ACCUM 1.0 PRISM 1 60 S ------------------------------------------------------------------------------------------------------------------------------------ 6595( 11) - 06/18/96 11:18 - [ 8] Visit: 04 Visit Requirements: PCS MODE Fine GROUP 4-6 WITHIN 10D On Hold Comments: Additional Comments: OCC-ACQ. Fine lock if possible; if not, coarse track is acceptable. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 210 P32.02 FOS/RD ACQ/BIN 4.3 MIRROR 1 26 S ONBOARD ACQ FOR 220 ARY ------------------------------------------------------------------------------------------------------------------------------------ 220 P32.02 FOS/RD ACQ/PEA 0.3 PRISM SCAN-STEP-X = 0.17,SCAN-STEP-Y = 1 26 S ONBOARD ACQ FOR 240 SAVE K 0.17,SEARCH-SIZE-X = 4, OFFSET PLOFF2 SEARCH-SIZE-Y = 4 Comments: Using Binary & Peak acquisitions to achieve 0.12" pointing accuracy (sequence Z+E1 from CAL/FOS-132). ------------------------------------------------------------------------------------------------------------------------------------ 240 P32.02 FOS/RD RAPID 1.0 PRISM 1485-89 READ-TIME = 0.231,SUB-STEP = 1, 1 120 S MAX DUR 300% 50 COMB = NO,STEP-TIME = 0.2 Comments: USE DIODES 139-512 ONLY Get spectrum of occulted star when it is away from Pluto. Same parameters as occultation. ------------------------------------------------------------------------------------------------------------------------------------ 6595( 11) - 06/18/96 11:18 - [ 9] Visit: 05 Visit Requirements: PCS MODE Fine AFTER 4 BY 4D TO 9D BETWEEN 23-AUG-96:12:52 AND 23-AUG- 96:12:55 same orient as 4 On Hold Comments: Additional Comments: OCC. Fine lock if possible; if not, coarse track is acceptable. Predicted mid-time 23-AUG-96:13:04, duration 4.5 minutes. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 250 P32.02 FOS/RD RAPID 1.0 PRISM 1485-89 READ-TIME = 0.231,SUB-STEP = 1, 1 1046 S END ORBIT USE OFFSET 50 COMB = NO,STEP-TIME = 0.2 PLOFF2 Comments: IGNORE SAA. Can split exposure across SAA. USE DIODES 139-512 ONLY ------------------------------------------------------------------------------------------------------------------------------------ 6595( 11) - 06/18/96 11:18 - [ 10] Visit: 06 Visit Requirements: PCS MODE Fine On Hold Comments: Additional Comments: Pluto spectra. Fine lock if possible; if not, coarse track is acceptable. Do not execute within +/- 45M of Visit 5. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 300 PLUTO FOS/RD ACQ/BIN 4.3 MIRROR 1 1.23 S ONBOARD ACQ FOR 310 ARY Comments: Do not execute within +/- 45M of Visit 5. ------------------------------------------------------------------------------------------------------------------------------------ 310 PLUTO FOS/RD ACQ/PEA 0.3 PRISM SCAN-STEP-X = 0.17,SCAN-STEP-Y = 1 1.24 S ONBOARD ACQ FOR 320-330 K 0.17,SEARCH-SIZE-X = 4, SEARCH-SIZE-Y = 4 Comments: Using Binary & Peak acquisitions to achieve 0.12" pointing accuracy (sequence Z+E1 from CAL/FOS-132). ------------------------------------------------------------------------------------------------------------------------------------ 320 PLUTO FOS/RD RAPID 1.0 PRISM READ-TIME = 0.231,SUB-STEP = 1, 1 66.99 S COMB = NO,STEP-TIME = 0.2 Comments: USE DIOES 139-512 ONLY (partial scattered light correction). ------------------------------------------------------------------------------------------------------------------------------------ 330 PLUTO FOS/RD ACCUM 1.0 PRISM 1 60 S ------------------------------------------------------------------------------------------------------------------------------------ 6595( 11) - 06/18/96 11:18 - [ 11] Summary Form for Proposal 6595 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACQ/PEAK RAPID ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCAN-STEP-X = 0.11 SCAN-STEP-Y = 0.11 SEARCH-SIZE-X = 5 SEARCH-SIZE-Y = 5 STEP-TIME = 0.2 COMB = NO SEARCH-SIZE-Y = 4 SUB-STEP = 1 SEARCH-SIZE-X = 4 READ-TIME = 0.231 SCAN-STEP-Y = 0.17 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE Fine GROUP 1-3 WITHIN 10D ONBOARD ACQ FOR 20 ONBOARD ACQ FOR 40 SAVE OFFSET PLOFF1 PCS MODE Fine AFTER 1 BY 4D TO 9D BETWEEN 28-JUL-96 03 20 AND 28-JUL-96 03 23 same orient as 1 END ORBIT USE OFFSET PLOFF1 PCS MODE Fine ONBOARD ACQ FOR 110 ONBOARD ACQ FOR 120-130 PCS MODE Fine GROUP 4-6 WITHIN 10D ONBOARD ACQ FOR 220 ONBOARD ACQ FOR 240 SAVE OFFSET PLOFF2 MAX DUR 300% PCS MODE Fine AFTER 4 BY 4D TO 9D BETWEEN 23-AUG-96 12 52 AND 23-AUG-96 12 55 same orient as 4 END ORBIT USE OFFSET PLOFF2 ONBOARD ACQ FOR 310 ONBOARD ACQ FOR 320-330 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR PRISM ------------------------------------------------------------------------------------------------------------------------------------ Target Names P31 PLUTO P32.02 ------------------------------------------------------------------------------------------------------------------------------------