7754( 7) - 05/22/00 13:23 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7754 Version: 7 Check-in Date: 22-May-2000 13:22:37 1.Proposal Title: Does Pluto Have a Haze Layer? ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Amanda Bosh Lowell Observatory CoI: James L. Elliot Massachusetts Institute of Technology N ------------------------------------------------------------------------------------ 5. 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. ------------------------------------------------------------------------------------ 7754( 7) - 05/22/00 13:23 - [ 2] Observations Description ------------------------ All observations are carried out with FGS-1 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, second, third, and fifth exposures in this orbit are of one of the reference stars in order to tie our astrometry in with ground-based astrometry. The fourth exposure is in TRANS mode, and it is set up to provide high-speed photometry of the occultation of PLUTO-OS and Pluto (or possibly Charon), 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 near 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 ------------------- 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 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. ------------------------------------------------------------------------------------ 7754( 7) - 05/22/00 13:23 - [ 3] Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7754( 7) - 05/22/00 13:23 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PLUTO-OS STAR RA=16H 41M 43.817S +/- 0.1S, J2000 V = 14.6+/-0.1 DEC=-11D 29' 27.09" +/- 1.0" Coordinate Source: Comments: NV1641438-112927 from USNO-A2.0 catalog 2 PL-1-REF CALIBRATION, RA=16H 41M 15.314S +/- 0.1S, J2000 V = 12.35+/-0.1 ASTROMETRIC DEC=-11D 30' 43.99" +/- 1.0" Coordinate Source: Comments: LO list #220 3 PL-2-REF CALIBRATION, RA=16H 41M 19.073S +/- 0.1S, J2000 V = 15.06+/-0.1 ASTROMETRIC DEC=-11D 30' 22.79" +/- 1.0" Coordinate Source: Comments: LO list #239 4 PL-3-REF CALIBRATION, RA=16H 41M 46.039S +/- 0.1S, J2000 V = 15.16+/-0.1 ASTROMETRIC DEC=-11D 29' 56.47" +/- 1.0" Coordinate Source: Comments: LO list #236 5 PL-4-REF CALIBRATION, RA=16H 41M 48.554S +/- 0.1S, J2000 V = 14.02+/-0.1 ASTROMETRIC DEC=-11D 28' 41.70" +/- 1.0" Coordinate Source: Comments: LO list #258 6 PL-5-REF CALIBRATION, RA=16H 42M 02.261S +/- 0.1S, J2000 V = 15.20+/-0.1 ASTROMETRIC DEC=-11D 32' 26.52" +/- 1.0" Coordinate Source: Comments: LO list #217 7 PL-6-REF CALIBRATION, RA=16H 42M 16.363S +/- 0.1S, J2000 V = 14.98+/-0.1 ASTROMETRIC DEC=-11D 31' 56.57" +/- 1.0" Coordinate Source: Comments: LO list #227 8 PLUTO STAR RA=16H 41M 34.168S +/- 0.1S, J2000 V = 13.7+/-0.1 DEC=-11D 28' 09.35" +/- 1.0" Coordinate Source: Comments: Nominal position of Pluto given for middle of Visit 2 7754( 7) - 05/22/00 13:23 - [ 5] Visit: 01 Visit Priority: Visit Requirements: PCS MODE FINE BETWEEN 1-Jul-2000 AND 25-Jul-2000 ORIENT 95D TO 97D 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 1 F583W 1 10 S POS TARG 0.0, 0.0 MAX DUR 10 S SEQ 10-100 NON-INT GS ACQ SCENARIO SINGLE ------------------------------------------------------------------------------------------------------------------------------------ 20 PL-4-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 30 PLUTO-OS FGS TRANS 1 F583W SCANS=17,STEP-SIZE=1 1 1020 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 35 PLUTO-OS FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 40 PL-4-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 60 PL-2-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 65 PL-3-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 80 PL-5-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 100 PL-4-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 7754( 7) - 05/22/00 13:23 - [ 6] Visit: 02 Visit Priority: Visit Requirements: PCS MODE FINE BETWEEN 23-Sep-2000:00:00:00.0 AND 23-Sep-2000:02:00:00.0 ORIENT 93D TO 94D 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 1 F583W 1 10 S POS TARG 0.0, 0.0 MAX DUR 10 S SEQ 10-130 NON-INT GS ACQ SCENARIO SINGLE ------------------------------------------------------------------------------------------------------------------------------------ 20 PL-4-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 30 PLUTO FGS TRANS 1 F583W SCANS=8,STEP-SIZE=1 1 480 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 40 PL-4-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 50 PLUTO-OS FGS TRANS 1 F583W SCANS=8,STEP-SIZE=1 1 480 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 60 PL-4-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 80 PL-2-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 90 PL-3-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 110 PL-5-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 130 PL-4-REF FGS POS 1 F583W 1 10 S SAME POS AS 10 MAX DUR 10 S ------------------------------------------------------------------------------------------------------------------------------------ 7754( 7) - 05/22/00 13:23 - [ 7] Visit: 03 Visit Priority: Visit Requirements: PCS MODE FINE BETWEEN 25-Sep-2000:08:00:00.0 AND 25-Sep-2000:11:00:00.0 ORIENT 93D TO 94D 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 1 F583W 1 8 S POS TARG 0.0, 0.0 MAX DUR 8 S SEQ 10-40 NON-INT GS ACQ SCENARIO SINGLE ------------------------------------------------------------------------------------------------------------------------------------ 15 PL-3-REF FGS POS 1 F583W 1 10 S MAX DUR 10 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 20 PL-4-REF FGS POS 1 F583W 1 8 S MAX DUR 8 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 30 PLUTO-OS FGS TRANS 1 F583W SCANS=26,STEP-SIZE=1 1 1560 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 40 PL-4-REF FGS POS 1 F583W 1 8 S SAME POS AS 10 MAX DUR 8 S ------------------------------------------------------------------------------------------------------------------------------------ 7754( 7) - 05/22/00 13:23 - [ 8] Summary Form for Proposal 7754 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations FGS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes POS TRANS ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCANS=17 STEP-SIZE=1 SCANS=8 SCANS=26 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE FINE BETWEEN 1-Jul-2000 AND 25-Jul-2000 ORIENT 95D TO 97D POS TARG 0.0, 0.0 MAX DUR 10 S SEQ 10-100 NON-INT GS ACQ SCENARIO SINGLE SAME POS AS 10 MAX DUR 10 S SAME POS AS 10 PCS MODE FINE BETWEEN 23-Sep-2000 00 00 00.0 AND 23-Sep-2000 02 00 00.0 ORIENT 93D TO 94D POS TARG 0.0, 0.0 MAX DUR 10 S SEQ 10-130 NON-INT GS ACQ SCENARIO SINGLE PCS MODE FINE BETWEEN 25-Sep-2000 08 00 00.0 AND 25-Sep-2000 11 00 00.0 ORIENT 93D TO 94D POS TARG 0.0, 0.0 MAX DUR 8 S SEQ 10-40 NON-INT GS ACQ SCENARIO SINGLE MAX DUR 10 S SAME POS AS 10 MAX DUR 8 S SAME POS AS 10 SAME POS AS 10 MAX DUR 8 S ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F583W ------------------------------------------------------------------------------------------------------------------------------------ Target Names PLUTO-OS PL-4-REF PL-2-REF PL-3-REF PL-5-REF PLUTO ------------------------------------------------------------------------------------------------------------------------------------