6487( 5) - 05/17/96 18:35 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6487 Version: 5 Check-in Date: 17-May-1996 18:31:57 1.Proposal Title: Spectrophotometry of Inner Satellites of Uranus ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle SOLAR SYSTEM GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Ben Zellner Georgia Southern University CoI: Bonnie Buratti Jet Propulsion Laboratory N CoI: Douglas Currie University of Maryland N CoI: Dan Pascu U. S. Naval Observatory N CoI: Kenneth Seidelmann U. S. Naval Observatory N CoI: Alex Storrs Space Telescope Science Institute N CoI: Eddie Wells Computer Sciences Corporation N ------------------------------------------------------------------------------------ 6. Abstract We propose spectrophotometry with the FOS/Red of the inner Uranian satellites Puck, Portia, and Juliet, which are impossible to observe from the ground. Small apertures will be used for accurate measurements of the scattered light from Uranus, and we expect to get good spectra over the wavelength range 0.28 to 0.80 microns. We will also obtain a high- quality spectrum of Miranda to wavelengths as short as 0.22 microns. The results will be interpreted with reference to known reflectance spectra for similar objects including C- and D-type asteroids, satellites and rings of outer planets, and laboratory spectra of dark carbon-bearing compounds. This programs follows our successful recovery of eight inner satellites of Uranus with the Planetary Camera in HST Cycle 4. ------------------------------------------------------------------------------------ 6487( 5) - 05/17/96 18:35 - [ 2] Observations Description ------------------------ We propose to use seven HST orbits to obtain spectral reflectances of four of the inner satellites of Uranus. Five orbits will be used to do the FOS observations of the satellites, and two orbits will be used to obtain FOS spectra of a solar analog standard star for use in calculating satellite reflectivities. The observations of satellites Miranda, Puck, Portia, and Juliet will be done in one visit of five orbits. The geocentric motion of Uranus will be only about 45 arcseconds during five orbits if the observations are scheduled within a few months of opposition. Therefore, a single pair of guide stars can be used throughout, and only one onboard target acquisition, of Miranda, is necessary. Blind offsets will be used to acquire the remaining three targets, which will leave about 34 minutes of useable observing time for each of Puck, Portia, and Juliet. For the inner satellites, correct removal of the scattered light from Uranus will be essential. Calculations based on our own observations of the Uranian system with the Planetary Camera show that, in the 0.3-arcsecond aperture of the FOS, the scattered light will range from about 10% of the signal for Puck at 8000 Angstrom to somewhat brighter than the signal for Juliet at 3000 Angstrom. Therefore, half of the available observing time will be used to measure the sky brightness 0.5 arcseconds from each satellite. For Miranda the sky background will be only about 0.1% of the signal, and sky measurements are not necessary. Miranda will be acquired via an ACQ/BINARY and two ACQ/PEAKs in the 0.3-arcsecond aperture, which will consume an entire orbit. The second orbit will be used to take a deep spectrum of Miranda with an exposure of 34 minutes. Puck, Portia, and Juliet will be observed in the next three orbits with 17-minute exposures on the satellite and 17 minutes on the sky. All observations will be made with the FOS/RD using the Prism and the 0.3-arcsecond aperture. For each observation moving target tracking of the satellite's motion will be required. Two orbits will be required to obtain FOS spectra of a solar analog standard star for use in converting spectral intensity measurements to reflectivities. The faintest known solar analog stars are near the upper brightness limit of the FOS/RD with Prism. In Cycle 4 program 3744 we used Hyades VB64, but at magnitude 8.1 it is brighter than the new nominal brightness limit of 8.4. VB64 is our preferred solar analog, but if it cannot be used, we will use Hyades VB142 (V mag.= 8.32). The brightness limit for ACQ/BINARY target acquisitions is 12.4 for the FOS/RD. Hence, a sequence of four or five ACQ/PEAK acquisitions into successively smaller apertures will be used and will require about an orbit and a half of spacecraft time. The exposure time for the prism and 0.3 aperture is about 10 seconds. The PI and several Co-Is of this program are also PI and Co- Is on program 6552, to observe several of the inner satellites of Jupiter. That program also requested two orbits for identical solar analog star measurements, but the TAC cut two orbits from the request. Although the TAC gave no instructions on this point, we believe that the cut was made so as not to duplicate the analog star measurements of this program. Thus we have included an exposure using the 0.5-PAIR aperture with the Prism. During the 1996 Meeting of the DPS, many HST observers expressed their needs for good measurements of solar analog stars with both the FOS and HRS. Since we had almost a half orbit left while pointing at such a star, we would like to add two exposures using the most widely used of the FOS gratings and apertures. We have chosen the G400H and G270H because of their wide use. We ask that these observations be considered non-proprietary. Real Time Justification ----------------------- The opposition of Uranus will be on July 25, 1996, and we request that our observations be scheduled within 6 weeks of that time. Thus, this program would be a candidate for scheduling early in Cycle 6. No supporting observations are required. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6487( 5) - 05/17/96 18:35 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: STSCI Ship Via: Email: wells@stsci.edu , ------------------------------------------------------------------------------------ 6487( 5) - 05/17/96 18:35 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 8 HD30246 EXT-STAR,G V-IV, RA=04H 46M 30.38S +/- J2000 V = 8.32+/-0.05 0.3",DEC=15D 28' 19.07" +/- 0.3" TYPE=G5V Comments: Solar analog star Hyades VB142. This is the faintest of the known solar analog stars. Should be observable with the smaller apertures. Proper motions from PPM Star Catalog. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 0.0059 -0.330 0.0 6487( 5) - 05/17/96 18:35 - [ 5] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: MIRANDA ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE MIRANDA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=URANUS | STD=MIRANDA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | TYPE=G2V | Target positions MUST be obtained V = 16.3+/-0.2 | from the updated JPL ephemeris based | on results from our program 5321. | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: PUCK ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE Puck ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=URANUS | STD=PUCK | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | TYPE=G2V | Target positions MUST be obtained V = 20.2+/-0.4 | from the updated JPL ephemeris based | on results from our program 5321. | ------------------------------------------------------------------------------------------------------------------------------------ 6487( 5) - 05/17/96 18:35 - [ 6] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: PUCK-SKY ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE PUCK ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=URANUS | STD=PUCK | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 18.5+/-0.5 | Sky at small offset from Puck to B-V = 0.56 | measure scattered light from Uranus. | Target positions MUST be obtained | from the updated JPL ephemeris based | on results from our program 5321. | Ephemeris Uncertainty: 500 S | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 4 | TARGET NAME: PORTIA ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE PORTIA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=URANUS | STD=PORTIA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | TYPE=G2V | Target positions MUST be obtained V = 21.0+/-0.4 | from the updated JPL ephemeris based | on results from our program 5321. | ------------------------------------------------------------------------------------------------------------------------------------ 6487( 5) - 05/17/96 18:35 - [ 7] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 5 | TARGET NAME: PORTIA-SKY ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE PORTIA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=URANUS | STD=PORTIA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | B-V = 0.56 | Sky at small offset from Portia to SURF(V) = 17.8+/-0.5 | measure light scattered from Uranus. | Target positions MUST be obtained | from the updated JPL ephemeris based | on results from our program 5321. | Ephemeris Uncertainty: 500 S | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 6 | TARGET NAME: JULIET ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE JULIET ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=URANUS | STD=JULIET | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | TYPE=G2V | Target positions MUST be obtained V = 21.5+/-0.4 | from the updated JPL ephemeris based | on results from our program 5321. | ------------------------------------------------------------------------------------------------------------------------------------ 6487( 5) - 05/17/96 18:35 - [ 8] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 7 | TARGET NAME: JULIET-SKY ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE Juliet ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=URANUS | STD=JULIET | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 17.8+/-0.5 | Sky at small offset from Juliet to B-V = 0.56 | measure light scattered from Uranus. | Target positions MUST be obtained | from the updated JPL ephemeris based | on results from our program 5321. | Ephemeris Uncertainty: 500 S | ------------------------------------------------------------------------------------------------------------------------------------ 6487( 5) - 05/17/96 18:35 - [ 9] Visit: 01 Visit Requirements: PCS MODE FINE BETWEEN 13-Jun-1996 AND 05-Sep-1996 On Hold Comments: Additional Comments: Ephemeris corrections required for exposures 7, 9, and 11 to uplink offsets to sky positions at same distance from Uranus as satellite positions. These cannot be determined until observation times are known. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 MIRANDA FOS/RD ACQ/BIN 4.3 MIRROR 1 13.4S SEQ 1-3 NON-INT ONBOARD ARY ACQ FOR 2 ------------------------------------------------------------------------------------------------------------------------------------ 2 MIRANDA FOS/RD ACQ/PEA 0.3 MIRROR SCAN-STEP-X=0.11,SCAN-STEP-Y=0.11 1 1.5S ONBOARD ACQ FOR 3 K ,SEARCH-SIZE-X=5,SEARCH-SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ 3 MIRANDA FOS/RD ACQ/PEA 0.3 MIRROR SCAN-STEP-X=0.052, 1 5S ONBOARD ACQ FOR 4-11 K SCAN-STEP-Y=0.052,SEARCH-SIZE-X=4 ,SEARCH-SIZE-Y=4 ------------------------------------------------------------------------------------------------------------------------------------ 4 MIRANDA FOS/RD ACCUM 0.3 PRISM 1 17.2M SEQ 4-5 NON-INT MIN DUR ------------------------------------------------------------------------------------------------------------------------------------ 5 MIRANDA FOS/RD ACCUM 0.3 PRISM 1 17.2M EXPAND MIN DUR ------------------------------------------------------------------------------------------------------------------------------------ 6 PUCK FOS/RD ACCUM 0.3 PRISM 1 17.5M SEQ 6-7 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 7 PUCK-SKY FOS/RD ACCUM 0.3 PRISM 1 17.5M REQ EPHEM CORR PUCK01 ------------------------------------------------------------------------------------------------------------------------------------ 8 PORTIA FOS/RD ACCUM 0.3 PRISM 1 17.5M SEQ 8-9 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 9 PORTIA-SKY FOS/RD ACCUM 0.3 PRISM 1 17.5M REQ EPHEM CORR PORTIA ------------------------------------------------------------------------------------------------------------------------------------ 10 JULIET FOS/RD ACCUM 0.3 PRISM 1 17.5M SEQ 10-11 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 11 JULIET-SKY FOS/RD ACCUM 0.3 PRISM 1 17.5M REQ EPHEM CORR JULIET ------------------------------------------------------------------------------------------------------------------------------------ 6487( 5) - 05/17/96 18:35 - [ 10] Visit: 02 Visit Requirements: PCS MODE FINE 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 ------------------------------------------------------------------------------------------------------------------------------------ 21 HD30246 FOS/RD ACQ/PEA 4.3 G270H SEARCH-SIZE-X=1,SEARCH-SIZE-Y=3, 1 1S ONBOARD ACQ FOR 26 SEQ K SCAN-STEP-Y=1.23 21-24 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 22 HD30246 FOS/RD ACQ/PEA 1.0 G270H SEARCH-SIZE-X=6,SEARCH-SIZE-Y=2, 1 1S ONBOARD ACQ FOR 26 K SCAN-STEP-X=0.61,SCAN-STEP-Y=0.61 ------------------------------------------------------------------------------------------------------------------------------------ 23 HD30246 FOS/RD ACQ/PEA 0.5 G270H SEARCH-SIZE-X=3,SEARCH-SIZE-Y=3, 1 1S ONBOARD ACQ FOR 26 K SCAN-STEP-X=0.29,SCAN-STEP-Y=0.29 ------------------------------------------------------------------------------------------------------------------------------------ 24 HD30246 FOS/RD ACQ/PEA 0.3 G270H SEARCH-SIZE-X=4,SEARCH-SIZE-Y=4, 1 1S ONBOARD ACQ FOR 26 K SCAN-STEP-X=0.11,SCAN-STEP-Y=0.11 ------------------------------------------------------------------------------------------------------------------------------------ 25 HD30246 FOS/RD ACQ/PEA 0.3 G270H SEARCH-SIZE-X=4,SEARCH-SIZE-Y=4, 1 1S ONBOARD ACQ FOR 26 K SCAN-STEP-X=0.052, SCAN-STEP-Y=0.052 ------------------------------------------------------------------------------------------------------------------------------------ 26 HD30246 FOS/RD ACCUM 0.5 G270H 1 8M Comments: Observations with this grating and aperture not requested in phase I. It is a non-proprietary solar analog star observation for any solar system programs using G270H. ------------------------------------------------------------------------------------------------------------------------------------ 27 HD30246 FOS/RD ACCUM 0.5 G400H 1 75S Comments: Observations with this aperture and grating were not requested in phase I. This is a non-proprietary solar analog observation for any other solar system programs using G400H. ------------------------------------------------------------------------------------------------------------------------------------ 28 HD30246 FOS/RD ACCUM 0.3 PRISM 1 10S Comments: Solar analog star for this program. ------------------------------------------------------------------------------------------------------------------------------------ 29 HD30246 FOS/RD ACCUM 0.5-PAI PRISM 1 10S R Comments: Solar analog star for program GO-6552. ------------------------------------------------------------------------------------------------------------------------------------ 6487( 5) - 05/17/96 18:35 - [ 11] Summary Form for Proposal 6487 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCAN-STEP-X=0.11 SCAN-STEP-Y=0.11 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SEARCH-SIZE-Y=4 SCAN-STEP-Y=1.23 SCAN-STEP-Y=0.61 SCAN-STEP-Y=0.29 SEARCH-SIZE-X=4 SCAN-STEP-Y=0.052 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE FINE BETWEEN 13-Jun-1996 AND 05-Sep-1996 SEQ 1-3 NON-INT ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 3 ONBOARD ACQ FOR 4-11 SEQ 4-5 NON-INT MIN DUR EXPAND MIN DUR SEQ 6-7 NON-INT REQ EPHEM CORR PUCK01 SEQ 8-9 NON-INT REQ EPHEM CORR PORTIA SEQ 10-11 NON-INT REQ EPHEM CORR JULIET PCS MODE FINE ONBOARD ACQ FOR 26 SEQ 21-24 NON-INT ONBOARD ACQ FOR 26 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR PRISM G270H G400H ------------------------------------------------------------------------------------------------------------------------------------ Target Names MIRANDA PUCK PUCK-SKY PORTIA PORTIA-SKY JULIET JULIET-SKY HD30246 ------------------------------------------------------------------------------------------------------------------------------------