8105( 17) - 06/14/99 10:37 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8105 Version: 17 Check-in Date: 14-Jun-1999 10:36:45 1.Proposal Title: Global Change on Pluto? ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: James Elliot Massachusetts Institute of Technology CoI: Dr. Amanda Bosh Lowell Observatory N CoI: Dr. Lawrence Wasserman Lowell Observatory N CoI: Dr. Otto Franz Lowell Observatory N ------------------------------------------------------------------------------------ 5. Abstract Pluto and Triton, two bodies that likely formed in the solar nebula (rather than a pre-planetary nebula), hold the promise of telling us much about early conditions in the outer solar system. Pluto and Triton are remarkably similar in size and density, and each suffered an early catastrophic event: Triton's retrograde orbit indicates that it was captured by Neptune, while Pluto's binding with Charon also required a large dissipation of energy. The low probability of such events for two isolated bodies implies that Pluto and Triton have remained from a much larger Kuiper belt population that existed in the past. Observation of a stellar occultation by last year with the FGS has shown that (i) Triton has been undergoing a period of global warming, and (ii) Triton has a much deeper troposphere than previously thought. A similar observation of an occultation by Pluto is proposed to probe whether it is undergoing global change as well. In addition to observing the occultation, we propose astrometric observations that will be critical for deploying portable telescopes and for interpreting Earth-based occultation observations, even if the HST proves not to be within the occultation path. ------------------------------------------------------------------------------------ 8105( 17) - 06/14/99 10:37 - [ 2] Observations Description ------------------------ All observations are carried out with FGS-3 and filter F583W. Orbit #1: In this orbit we accomplish three goals: (i) Determine whether PLUTO-OS is a double with one set of TRANS mode exposures; (ii) determine the position of PLUTO-OS relative to a local network with POS mode exposures of it and some nearby stars; (iii) calibrate the photometry of the TRANS mode (to be used for the occultation in Orbit #3), using the same TRANS mode exposure used to check for duplicity. Results from (i) may affect the final occultation prediction and the deployment of ground stations, so the results are needed as early in Cycle 8 as practical. Orbit #2: The goals for this orbit are: (i) astrometry of Pluto and PLUTO-OS as soon as possible when Pluto and PLUTO-OS can be observed together in the pickle, (ii) to secure a set of standard scans of Pluto in the TRANS mode that will be needed for reduction of Orbit #3 observations, and (iii) relative photometry of PLUTO-OS and Pluto by observing both bodies in the TRANS mode. Since Pluto is moving too rapidly, POS mode observations of it are not possible. The relative astrometry will be carried out by comparison of the TRANS mode observations. PLUTO-OS will be observed in both the POS and TRANS mode to determine the correction between the two modes of astrometry. POS mode observations of the network stars are included in order to more accurately relate HST astrometry to ground-based astrometry. Orbit #3: The first and last POS-mode exposures in this orbit are of one of the reference stars in order to tie our astrometry in with ground-based astrometry. The second and fifth exposures are in TRANS mode, and they will include PLUTO-OS, Pluto, and its satellite Charon. These two are set up to provide accurate relative astrometry before and after the occultation. The third exposure is in TRANS mode, and it is set up to provide high-speed photometry of the occultation of PLUTO-OS and Pluto, should the occultation be visible from the HST (hopefully it will). These exposures have been set up under the optimisitic assumption that the occulation will occur at the midpoint of the orbit window. Since this optimistic assumption may not be realized, the exposures will have to be adjusted later, when the occultation prediction has been refined and we know the phase of the HST orbit (two weeks prior to the observations). The orbit has been selected to include our best estimate of the midtime of the occultation at this time (Phase II submission). Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8105( 17) - 06/14/99 10:37 - [ 3] Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8105( 17) - 06/14/99 10:37 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PL-1-REF CALIBRATION, RA=16H 32M 56.401S +/- 0.1S, J2000 V = 15.58+/-0.1 ASTROMETRIC DEC=-10D 38' 02.08" +/- 1.0" Comments: USNO A2-0 star 2 PL-2-REF CALIBRATION, RA=16H 32M 45.098S +/- 0.1S, J2000 V = 15.09+/-0.1 ASTROMETRIC DEC=-10D 36' 44.24" +/- 1.0" Comments: LO list #90 3 PL-3-REF CALIBRATION, RA=16H 32M 35.830S +/- 0.1S, J2000 V = 15.15+/-0.1 ASTROMETRIC DEC=-10D 37' 50.16" +/- 1.0" Comments: LO list #103 4 PL-4-REF CALIBRATION, RA=16H 32M 19.138S +/- 0.1S, J2000 V = 14.75+/-0.1 ASTROMETRIC DEC=-10D 34' 55.09" +/- 1.0" Comments: LO list #177 5 PLUTO-OS STAR RA=16H 32M 43.639S +/- 0.1S, J2000 V = 11.8+/-0.1 DEC=-10D 38' 23.80" +/- 1.0" Comments: LO list #124 6 PLUTO STAR RA=16H 32M 21.624S +/- 0.1S, J2000 V = 13.7+/-0.1 DEC=-10D 35' 19.14" +/- 1.0" Comments: Nominal position of Pluto given for middle of Visit 2 8105( 17) - 06/14/99 10:37 - [ 5] Visit: 01 Visit Priority: Visit Requirements: PCS MODE FINE BETWEEN 19-Jun-1999 AND 12-Jul-1999 ORIENT 97D TO 120D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 PLUTO-OS FGS POS 3 F583W 1 15 S POS TARG 0.0, 0.0 MAX DUR 55 S SEQ 10-90 NON-INT GS ACQ SCENARIO SINGLE ------------------------------------------------------------------------------------------------------------------------------------ 20 PLUTO-OS FGS TRANS 3 F583W SCANS=16,STEP-SIZE=1 1 960 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 40 PL-3-REF FGS POS 3 F583W 1 30 S SAME POS AS 10 MAX DUR 55 S ------------------------------------------------------------------------------------------------------------------------------------ 50 PL-1-REF FGS POS 3 F583W 1 60 S SAME POS AS 10 MAX DUR 60 S ------------------------------------------------------------------------------------------------------------------------------------ 60 PL-2-REF FGS POS 3 F583W 1 30 S SAME POS AS 10 MAX DUR 55 S ------------------------------------------------------------------------------------------------------------------------------------ 70 PL-4-REF FGS POS 3 F583W 1 30 S SAME POS AS 10 MAX DUR 55 S ------------------------------------------------------------------------------------------------------------------------------------ 80 PL-3-REF FGS POS 3 F583W 1 30 S SAME POS AS 10 MAX DUR 55 S ------------------------------------------------------------------------------------------------------------------------------------ 90 PLUTO-OS FGS POS 3 F583W 1 10 S SAME POS AS 10 MAX DUR 30 S ------------------------------------------------------------------------------------------------------------------------------------ 8105( 17) - 06/14/99 10:37 - [ 6] Visit: 02 Visit Priority: Visit Requirements: PCS MODE FINE BETWEEN 20-Sep-1999:18:00:00.0 AND 21-Sep-1999 ORIENT 96D TO 98D On Hold Comments: Additional Comments: Target PLUTO is a moving object and will need a correct position inserted when this visit is actually executed. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 PLUTO-OS FGS POS 3 F583W 1 10 S POS TARG 0.0, 0.0 MAX DUR 60 S SEQ 10-100 NON-INT GS ACQ SCENARIO SINGLE ------------------------------------------------------------------------------------------------------------------------------------ 20 PLUTO FGS TRANS 3 F583W SCANS=12,STEP-SIZE=1 1 600 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 30 PL-4-REF FGS POS 3 F583W 1 30 S SAME POS AS 10 MAX DUR 60 S ------------------------------------------------------------------------------------------------------------------------------------ 40 PL-3-REF FGS POS 3 F583W 1 30 S SAME POS AS 10 MAX DUR 60 S ------------------------------------------------------------------------------------------------------------------------------------ 50 PLUTO-OS FGS POS 3 F583W 1 10 S SAME POS AS 10 MAX DUR 30 S ------------------------------------------------------------------------------------------------------------------------------------ 60 PLUTO-OS FGS TRANS 3 F583W SCANS=12,STEP-SIZE=1 1 360 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 70 PLUTO-OS FGS POS 3 F583W 1 10 S SAME POS AS 10 MAX DUR 30 S ------------------------------------------------------------------------------------------------------------------------------------ 80 PL-1-REF FGS POS 3 F583W 1 60 S SAME POS AS 10 MAX DUR 60 S ------------------------------------------------------------------------------------------------------------------------------------ 90 PL-2-REF FGS POS 3 F583W 1 30 S SAME POS AS 10 MAX DUR 60 S ------------------------------------------------------------------------------------------------------------------------------------ 100 PL-3-REF FGS POS 3 F583W 1 30 S SAME POS AS 10 MAX DUR 60 S ------------------------------------------------------------------------------------------------------------------------------------ 8105( 17) - 06/14/99 10:37 - [ 7] Visit: 03 Visit Priority: Visit Requirements: PCS MODE FINE BETWEEN 26-Sep-1999 AND 26-Sep-1999:03:00:00.0 ORIENT 96D TO 98D On Hold Comments: Additional Comments: This visit must contain the actual time of the occultation of star PLUTO-OS by PLUTO which is TBD. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 PLUTO-OS FGS POS 3 F583W 1 10 S POS TARG 0.0, 0.0 MAX DUR 60 S SEQ 10-60 NON-INT GS ACQ SCENARIO SINGLE ------------------------------------------------------------------------------------------------------------------------------------ 20 PL-3-REF FGS POS 3 F583W 1 30 S MAX DUR 60 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 30 PLUTO-OS FGS TRANS 3 F583W SCANS=8,STEP-SIZE=1 1 400 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 40 PLUTO-OS FGS TRANS 3 F583W SCANS=26,STEP-SIZE=1 1 650 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 50 PLUTO-OS FGS TRANS 3 F583W SCANS=8,STEP-SIZE=1 1 400 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 60 PL-3-REF FGS POS 3 F583W 1 30 S SAME POS AS 10 MAX DUR 60 S ------------------------------------------------------------------------------------------------------------------------------------ 8105( 17) - 06/14/99 10:37 - [ 8] Summary Form for Proposal 8105 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 3 ------------------------------------------------------------------------------------------------------------------------------------ Configurations FGS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes POS TRANS ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCANS=16 STEP-SIZE=1 SCANS=12 SCANS=8 SCANS=26 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE FINE BETWEEN 19-Jun-1999 AND 12-Jul-1999 ORIENT 97D TO 120D POS TARG 0.0, 0.0 MAX DUR 55 S SEQ 10-90 NON-INT GS ACQ SCENARIO SINGLE SAME POS AS 10 SAME POS AS 10 MAX DUR 55 S SAME POS AS 10 MAX DUR 60 S SAME POS AS 10 MAX DUR 30 S PCS MODE FINE BETWEEN 20-Sep-1999 18 00 00.0 AND 21-Sep-1999 ORIENT 96D TO 98D POS TARG 0.0, 0.0 MAX DUR 60 S SEQ 10-100 NON-INT GS ACQ SCENARIO SINGLE PCS MODE FINE BETWEEN 26-Sep-1999 AND 26-Sep-1999 03 00 00.0 ORIENT 96D TO 98D POS TARG 0.0, 0.0 MAX DUR 60 S SEQ 10-60 NON-INT GS ACQ SCENARIO SINGLE MAX DUR 60 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F583W ------------------------------------------------------------------------------------------------------------------------------------ Target Names PLUTO-OS PL-3-REF PL-1-REF PL-2-REF PL-4-REF PLUTO ------------------------------------------------------------------------------------------------------------------------------------