Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5321 Report Date: 18-Jul-95:17:09 Version: ********** Check-in Date: ********** 1.Proposal Title: RECOVERY OF INNER SATELLITES OF URANUS CYCLE4MEDIUM ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID SOLAR SYSTEM GO Sub Category SATELLITES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Kenneth Seidelmann 3630 USA 202-653-1545 ------------------------------------------------------------------------------------ 7. Abstract Ten inner satellites of Uranus were discovered by Voyager 2 at the beginning of 1986. Since the observations were taken over only a one- month period, their orbital positions are currently uncertain by 5 to 110 degrees. No spectral data were obtained by Voyager, and the objects have not been observed since. We propose to recover these satellites with the Planetary Camera of the WFPC2, in order to determine positions which will provide accurate mean motions and improved orbital elements. The accurate mean motions will permit investigations of dynamical resonances which are known to exist among the satellites and with the rings. Also we will take images in multiple filters to obtain some information about the compositions of the satellites. The improved ephemerides resulting from this work will allow more detailed study of the objects with the Faint Object Spectrograph in subsequent HST cycles. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 0.09 par: 0 10. Num targs pri: 12 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5321 PI: Kenneth Seidelmann Proposal Title: RECOVERY OF INNER SATELLITES OF URANUS CYCLE4MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Kenneth Seidelmann 3630 USA Dan Pascu 3630 USA Douglas Currie 2620 USA Charles Kowal 1780 USA Eddie Wells 1780 USA Ben Zellner 1780 USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We propose to take paired images of the inner satellites of Uranus in B, V, R, and I filters in the Planetary Camera during three visits, each visit taking one HST orbit. The orbital periods of the satellites are such that the visits should be separated by approximately six hours or four HST orbits. Eleven short exposures will be taken on each visit, for three visits. No interactive or onboard target acquisition will be needed. The PC frames will also contain well- exposed images of the satellites Miranda and Ariel, which have accurately known ephemerides and will independently calibrate the roll angle of each frame and provide a check on the plate scale. They will also provide the photometric and colorimetric calibration. Uranus itself will be allowed to saturate (but not bloom) on the CCDs, and all astrometric reductions will be done in a satellite-to -satellite mode without reference to the planet. Since Uranus will generally be saturated we do not expect to obtain useful images of the planet, or of its rings. However if any of the images should show planetary or ring features we will call upon experts in the appropriate fields for analysis and interpretation. Wide-band filters are chosen to maximize photon count while keeping the exposures short enough to avoid motion blur. We will track on Uranus, and due to their orbital motions the satellites would blur more than one PC pixel in about 60 seconds, which is the limiting factor for the B filter. In V and R the image of Uranus would bloom in exposures longer than about 18 and 26 seconds, respectively. Finally, exposures in the I filter are limited to about 50 seconds to avoid blooming of Ariel. In the baseline exposures Ariel will saturate in V, R, and I, so we also propose to add a shorter exposure (5 to 10 seconds) in each. In one HST orbital visibility period it should be possible to do each baseline exposure twice to facilitate recognition and removal of cosmic rays, plus each shorter exposure once, for a total of 11 images per visit. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The inner satellites of Uranus have not been observed from the ground, and due to the uncertainties of their orbital positions they cannot presently be observed by small-aperture techniques from space. Until improved orbits are obtained they can only be observed with the Hubble Space Telescope in an imaging mode. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. Uranus will be at opposition on July 17, 1994, and the optimum geometry would be obtained within a few weeks of opposition. However Uranus is so distant that little resolution or signal would be lost even if pointing constraints of HST should continue to require that the observations be made several months away from opposition. Page 3 ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Unless there are unexpected problems with the flat-field properties, noise, or stability of the WFPC2 Planetary Camera, no special calibrations should be required. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. None. ------------------------------------------------------------------------------------ 9. Description of previous HST work. Seidelmann and Currie are members of the WF/PC IDT Team. The GTO programs are not closely related to this proposal. Zellner is PI of the following programs, none of which are closely related to this proposal: - A solar-system Target of Opportunity proposal was submitted for HST Cycle 1 with Co-Investigators including Seidelmann, Pascu, and Kowal. It was approved as program 2432 and was activated in April 1992 for PC images of newly discovered object 1992AD = 5145 Pholus. - A Target of Opportunity proposal essentially identical to 2432 was submitted for Cycle 3 and approved as program 4527. It will be activated if a sufficiently interesting target should appear. - Program 3744, "Spectrophotometry of Phobos and Deimos" was initially approved but not executed for Cycle 1, then re-submitted and approved for Cycle 2. Observations were taken in late 1992 and early 1993. - Program 4521, "Asteroid Shape and Duplicity", has been approved for Cycle 3. We expect that the first observations will be taken in July 1993. Zellner and Wells were associated with HST DD program 4748 for images of the earth-approaching object 4179 Toutatis in December 1992. Zellner is also co-investigator on a DD program, approved but not yet numbered at this writing, for images and spectrophotometry of comet 1993e in mid-1993. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Kowal, Wells, and Zellner will be chiefly responsible for Phase II proposal submission, for actual implementation of the program, and for reduction and deconvolution of the raw data. Mainframe computers and peripherals and STSDAS software for reduction of the raw images are available at STScI. A VaxStation 4000 Model 60 is budgeted in Cycle 3 program 4521 for analysis of PC images of asteroids and will also be used for this program. A cpu upgrade to Model 90 is budgeted here. CSC also provides a pool of research assistants and data technicians as well as administrative and secretarial support for research programs. The U. S. Naval Observatory will provide the necessary computer facilities, readily available software, and personnel time of the PI and Co-I for scientific analysis, interpretation, and communication of the results. Only support for temporary help for data analysis is being requested here. The University of Maryland will provide, as a contribution to this project, one man month of effort by Professor Currie. It will also contribute the use of two University of Maryland computing systems, DEC 3100 computers, to be used as needed to perform the image analysis required for this project. ------------------------------------------------------------------------------------ 11. Address Information Name: Kenneth Seidelmann Category: PI Institution: 3630 Address: U S Naval Observatory Orbital Mechanics Dept 3450 Massachusetts Ave., N.W. City: Washington, DC State: Zip Code: 203925420 Country: USA Telephone: 202-653-1545 Telex (or e-mail): omd@ariel.usno.navy.mil ------------------------------------------------------------------------------------ Page 4 Name: CHARLES T. KOWAL Category: CON Institution: 1780 Address: SPACE TELESCOPE SCIENCE INSTITUTE 3700 SAN MARTIN DRIVE City: BALTIMORE State: MD Zip Code: 21218 Country: USA Telephone: (410) 338-4535 Telex (or e-mail): kowal@stsci ------------------------------------------------------------------------------------ TARGET LIST b)Solar System Targets ID = 5321 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: URANUS ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET URANUS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = URANUS | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ REF | DATA | COMMENTS | | 1 |V=5.5 +/- 1.0 | | ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5321 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 URANUS WFPC2 IMAGE PC1-FIX F439W 1 60S 1 1 1 CYCLE 4 GROUP 1.000-1.061 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 1.001 URANUS WFPC2 IMAGE PC1-FIX F439W 1 120S 1 1 1 CYCLE 4 ------------------------------------------------------------------------------------------------------------------------------------ 1.01 URANUS WFPC2 IMAGE PC1-FIX F569W 1 10S 1 1 1 CYCLE 4 ------------------------------------------------------------------------------------------------------------------------------------ 1.02 URANUS WFPC2 IMAGE PC1-FIX F569W 1 18S 1 1 1 CYCLE 4 ------------------------------------------------------------------------------------------------------------------------------------ 1.021 URANUS WFPC2 IMAGE PC1-FIX F569W 1 35S 1 1 1 CYCLE 4 ------------------------------------------------------------------------------------------------------------------------------------ 1.03 URANUS WFPC2 IMAGE PC1-FIX F675W 1 8S 1 1 1 CYCLE 4 ------------------------------------------------------------------------------------------------------------------------------------ 1.04 URANUS WFPC2 IMAGE PC1-FIX F675W 1 26S 1 1 1 CYCLE 4 ------------------------------------------------------------------------------------------------------------------------------------ 1.041 URANUS WFPC2 IMAGE PC1-FIX F675W 1 50S 1 1 1 CYCLE 4 ------------------------------------------------------------------------------------------------------------------------------------ 1.05 URANUS WFPC2 IMAGE PC1-FIX F791W 1 12S 1 1 1 CYCLE 4 ------------------------------------------------------------------------------------------------------------------------------------ 1.06 URANUS WFPC2 IMAGE PC1-FIX F791W 1 50S 1 1 1 CYCLE 4 ------------------------------------------------------------------------------------------------------------------------------------ 1.061 URANUS WFPC2 IMAGE PC1-FIX F791W 1 100S 1 1 1 CYCLE 4 REPEAT 1.000-1.061 EVERY 6H +/- 3H FOR 2 MORE TIMES ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5321 [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 0.09 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category SATELLITES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; GROUP 1.000-1.061 NO GAP REPEAT 1.000-1.061 EVERY 6H +/- 3H FOR 2 MORE TIMES ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F439W F569W F675W F791W ------------------------------------------------------------------------------------------------------------------------------------ Target Names URANUS ------------------------------------------------------------------------------------------------------------------------------------