Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 1085c Report Date: 09-May-96:16:08 Version: ********** Check-in Date: ********** 1.Proposal Title: ROTATION PERIODS OF COMETARY NUCLEI ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID SOLAR SYSTEM GTO/HSP Sub Category COMETS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Robert C. Bless WISCONSIN, UNIVERSITY OF USA 608-262-1715 ------------------------------------------------------------------------------------ 7. Abstract Comets are thought to be samples of primordial materials from which the solar system formed that have been stored in the Oort cloud, undisturbed from their original state, since the planets accreted (4.6 billion years ago). The rotation period of a cometary nucleus is a fundamental parameter that influences the heat budget, which in turn controls the sublimation rate of ice and dust from the nucleus. Rotation periods of cometary nuclei have proven difficult to measure from Earth because of the interferring influence of the coma. The solution is to search for periodicities in the comet's light curve when it is far enough from Earth to be inactive. We propose to observe a distant comet and comet Halley for a total of 4 hours each in order to establish these rotation periods. ------------------------------------------------------------------------------------ 8. Scientific Key Words: COMET NUCLEI, LIGHT CURVE, ROTATION PERIODS ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 10.00 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 1085c PI: Robert C. Bless Proposal Title: ROTATION PERIODS OF COMETARY NUCLEI ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Edward L. Robinson TEXAS, UNIVERSITY OF USA Robert C. Bless WISCONSIN, UNIVERSITY OF USA G. W. Van Citters NATIONAL SCIENCE FOUNDATION USA Joseph F. Dolan NASA, GODDARD SPACE FLIGHT USA CENTER Richard L. White SPACE TELESCOPE SCIENCE USA INSTITUTE James L. Elliot MASSACHUSETTS INSTITUTE OF USA TECHNOLOGY ------------------------------------------------------------------------------------ 3. Description of proposed observations. The nuclei of Comet Halley and another distant comet will be observed for a total of 4 (four) hours each, spread over a period of 30-50 hours, in order to establish their rotation periods. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Precise photometry of faint cometary nuclei has not been highly successful from Earth. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. Data will be reduced and analyzed at MIT with the VAX 11-750 belonging to the planetary astronomy group. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). TBD ------------------------------------------------------------------------------------ 13. Observing comet Halley and another comet (TBD) when distant enough from the sun to be inactive with the HSP over a period of time will establish its light curve, from which its rotation period can be derived if the nucleus has albedo features and/or a non-spherical shape, and its rotation axis is not parallel to the line of sight. ------------------------------------------------------------------------------------ 11. Address Information Name: ROBERT C. BLESS Category: PI Institution: UNIVERSITY OF WISCONSIN Address: DEPARTMENT OF ASTRONOMY City: MADISON State: WI Zip Code: 53706 Country: USA Telephone: 608-262-1715 Telex (or e-mail): ------------------------------------------------------------------------------------ Name: JAMES L. ELLIOT Category: CON Institution: MASSACHUSETTS INSTITUTE OF TECHNO Address: BLDG. 54-422 City: CAMBRIDGE State: MA Zip Code: 02139 Country: USA Telephone: 617-253-6308 Telex (or e-mail): 921473 MIT CAM ------------------------------------------------------------------------------------ TARGET LIST b)Solar System Targets ID = 1085c [ 3] ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: HALLEY ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: COMET HALLEY NUCLEUS WHEN NOT HIGHLY ACTIV E ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | JPL EPHEMERIS | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ REF | DATA | COMMENTS | | 1 |V=18+/-4 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET LIST c)Generic Targets ID = 1085c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 7 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Selection Criteria |Acqui|FLX| Flux data No | Name | Description | |Prblm|REF| | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 COMET-NUC NUCLEUS OF AN INACTIVE INACTIVE COMET NUCLEUS SELECTED BY 1 V=17+/-3 COMET ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 1085c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 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 DEFINE # HSP/ ACQ 10 CLEAR 1 5 M 5 1 2 ONBOARD ACQ FOR 2 HSP-SER ACQ 1S ------------------------------------------------------------------------------------------------------------------------------------ 2 ^ ^ HSP/ 1APER 0.4 F400LP 1 40M 50 1 2 REPEAT 2 EVERY 7H PHOT 1S +/- 2H FOR 5 MORE TIMES ------------------------------------------------------------------------------------------------------------------------------------ 3 USE HSP HALLEY -SER ------------------------------------------------------------------------------------------------------------------------------------ 4 USE HSP COMET-NUC -SER ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 1085c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HSP/ACQ HSP/PHOT ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ 1APER ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GTO/HSP ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 10.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category COMETS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2 REPEAT 2 EVERY 7H +/- 2H FOR 5 MORE TIMES ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements CLEAR F400LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names HALLEY COMET-NUC ------------------------------------------------------------------------------------------------------------------------------------