Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4225c Report Date: 09-May-96:19:27 Version: ********** Check-in Date: ********** 1.Proposal Title: SATURN RING DYNAMICS - CONT OF 3375 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID SOLAR SYSTEM GTO/HSP 3375 Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Robert C. Bless WISCONSIN, UNIVERSITY OF USA 608-262-1715 ------------------------------------------------------------------------------------ 7. Abstract Understanding the dynamics of the rings is essential to our eventual understanding of their origin. Did they form recently or along with Saturn itself? We propose a series of stellar occultation observations in order to continue the dynamical investigation of Saturn's rings, at high spatial resolution, begun by the Voyager spacecraft. Revision History: Submitted to STScI on 6/25/92--BJW 6/25/92; ------------------------------------------------------------------------------------ 8. Scientific Key Words: SATURN'S RINGS, OCCULTATIONS, RING DYNAMICS ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 9.50 par: 0 10. Num targs pri: 17 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HSP ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4225c PI: Robert C. Bless Proposal Title: SATURN RING DYNAMICS - CONT OF 3375 ------------------------------------------------------------------------------------ 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. We plan to use the ST orbit parameters and catalogs of the objects of interest to identify those occultations of sufficient signal-to-noise ratio to achieve the goals outlined in Section 2. Each observation will require (i) a set of two sequential acquisitions, (ii) a scan of about 30-40 arcseconds along the track that the object will follow relative to Saturn's rings; and (iii) a time series run on the object with whatever filter-aperture combination that is chosen for the observation. For some occultations to be observed in the far uv, prior multi- filter photometry of the object will be necessary in order to determine the most appropriate filter to use for the occultation. The default filter set is F750W/F320N. For now, we shall assume that the calibration and observation time will average about 3 hours per occultation observed. About ten occultations would be required to achieve our goals of establishing orbits for the ringlets and other sharp-edged features of the system. For at ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. We can achieve a much better signal-to-noise ratio for Saturn ring occultations than would be possible from the ground because of (i) the absence of scintillation noise, which has strong components at frequencies corresponding to the occultation timescales, and (ii) our ability to reject background light from the rings themselves by employing small focal plane apertures. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. Acquisition of the star near Saturn may prove to be difficult. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. A prior scan over 30-40 arcseconds is needed to map the scattered light field, which is needed for the data reduction. ------------------------------------------------------------------------------------ 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. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. SV test HSP09A must be completed before these observations are made because the exact observation sequence may need to be modified depending on the results of the SV test. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Data reduction and analysis will be supported on computer facilities at MIT. Page 3 ------------------------------------------------------------------------------------ 13. Observations of a series of stellar occultations by Saturn's rings with the HSP (or perhaps FOS) can provide precise orbits of ringlets, other sharp features, waves, and other phenomena in the Saturn system at high spatial resolution. From these data further understanding of the present dynamical state of the ring system can be gained. This understanding should improve our knowledge of the past history and conditions of formation of the rings. ------------------------------------------------------------------------------------ 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 a) Fixed Targets ID = 4225c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 13 GSC6349- A,137 PLATE-ID = 018A, J2000 BKG 1 V = 13.36 +/- 0.3 01499 RA = 20H 59M 33.561S +/- 2 B = 14.11 +/- 0.3 0.04", 3 R = 13.13 +/- 0.3 DEC = -18D 09' 48.88" +/- 0.05", Comments: TARGET DESCR. STAR TO BE OCCULTED BY SATURN. CLOSE APPROACH AT 30-SEP-92:08:09 SOLAR ELONG 124D ------------------------------------------------------------------------------------------------------------------------------------ 14 01499-OFFSET A,140 PLATE-ID = 018A, J2000 1 B = 13.53 +/- 0.56 GSC6349- RA = 20H 59M 31.083S +/- 01365 0.05", DEC = -18D 09' 25.60" +/- 0.06", Comments: TARGET DESCR. OFFSET TARGET FOR GSC6349 -01499 ------------------------------------------------------------------------------------------------------------------------------------ TARGET LIST b)Solar System Targets ID = 4225c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 19 | TARGET NAME: 01499-BACKGROUND ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: OFFSET SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = SATURN | TYPE = POS_ANGLE, | RAD = 20, | ANG = 72.5, | REF = NORTH | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ REF | DATA | COMMENTS | | | | FOR USE IN A SCAN OF BACKGROUND | | LEVELS ALONG THE PATH OF THE | | OCCULTED STAR | ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4225c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 4 DEFINE # HSP/ ACQ 1 1S 1 1 PCS MODE F ONBRD- VIS ACQ Comments: USE FINE LOCK FOR OFFSET TARGET ACQ IF BRIGHT ENOUGH GUIDE STARS CAN BE FOUND. IF NOT, COARSE TRACK IS ACCEPTABLE. ------------------------------------------------------------------------------------------------------------------------------------ 6 DEFINE # HSP/ SPLIT 1.0 F750W/ # 1 1S 1 1 SPATIAL SCAN BACK- PMT/ F320N SCAN VIS ------------------------------------------------------------------------------------------------------------------------------------ 7 DEFINE # HSP/ SPLIT 1.0 F750W/ # 1 1M 1 1 CRIT OBS RING- PMT/ F320N PCS MODE F OCC VIS Comments: USE FINE LOCK FOR OCCULTATION OBSERVATIONS IF BRIGHT ENOUGH GUIDE STARS CAN BE FOUND. IF NOT, COARSE TRACK IS ACCEPTABLE. ------------------------------------------------------------------------------------------------------------------------------------ 20.01 USE 01499- SAMPLE- X533 SEQ 20.01 - 20.03 BACK- BACKGROUND TIME=0.05 GROUP 20.01 - SCAN PRECISION=HIGH 20.04 WITHIN 9H DATA-FORMAT=ALL CYCLE 2/20.01 - PMT-ANALOG=1000 20.20 VIS-ANALOG=100 ------------------------------------------------------------------------------------------------------------------------------------ 20.02 USE 01499- SAMPLE-TIME=0.1 X533 BACK- BACKGROUND PRECISION=HIGH SCAN DATA-FORMAT=ALL PMT-ANALOG=1000 VIS-ANALOG=100 ------------------------------------------------------------------------------------------------------------------------------------ 20.03 USE 01499- SAMPLE- X533 BACK- BACKGROUND TIME=0.05 SCAN PRECISION=HIGH DATA-FORMAT=ALL PMT-ANALOG=1000 VIS-ANALOG=100 ------------------------------------------------------------------------------------------------------------------------------------ 20.04 USE 01499- X40 ONBOARD ACQ FOR ONBRD- OFFSET 20.10 ACQ SEQ 20.04 - 20.10 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4225c [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 20.1 USE GSC6349- SAMPLE-TIME=0.1 X100 AT 30-SEP-92:04:01 RING- 01499 PRECISION=HIGH +/- 1M OCC DATA-FORMAT=ALL PMT-ANALOG=1000 VIS-ANALOG=100 Comments: END EXPOSURE AT 30-SEP- 92:06:40. ------------------------------------------------------------------------------------------------------------------------------------ 20.14 USE 01499- X40 ONBOARD ACQ FOR ONBRD- OFFSET 20.20 ACQ SEQ 20.14 - 20.20 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 20.2 USE GSC6349- SAMPLE-TIME=0.1 X50 AT 30-SEP-92:10:01 RING- 01499 PRECISION=HIGH +/- 1M OCC DATA-FORMAT=ALL PMT-ANALOG=1000 VIS-ANALOG=100 Comments: END EXPOSURE AT 30-SEP- 92:11:40. ------------------------------------------------------------------------------------------------------------------------------------ Scan Paramters Form Proposal ID: 4225c [ 8] ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 1 Exposure Logsheet lines: 20.01, 20.03 FGS Scan: CONTINUOUS Dwell Only: dwell points/line: 0 Seconds per dwell: 0.00 Scan width (arc-secs): 0.0000 Scan length (arc-secs): 62.5000 Angle between sides (degrees) 90.00 Number of lines: 1 Scan rate (arc-sec/sec): 0.0750 PA of first scan line (degrees) 255.000 Scan frame (CEL or S/C): CEL Length Offset (arc-sec): 0. Width Offset (arc-sec): 0. ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 2 Exposure Logsheet lines: 20.02 FGS Scan: CONTINUOUS Dwell Only: dwell points/line: 0 Seconds per dwell: 0.00 Scan width (arc-secs): 3.0000 Scan length (arc-secs): 62.5000 Angle between sides (degrees) 90.00 Number of lines: 5 Scan rate (arc-sec/sec): 0.0750 PA of first scan line (degrees) 255.000 Scan frame (CEL or S/C): CEL Length Offset (arc-sec): 0. Width Offset (arc-sec): 1.5000 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4225c [ 9] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HSP/VIS HSP/PMT/VIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ SPLIT ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMPLE-TIME PRECISION DATA-FORMAT PMT-ANALOG VIS-ANALOG ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GTO/HSP ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 9.50 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE F; SPATIAL SCAN; CRIT OBS; SEQ 20.01 - 20.03; GROUP 20.01 - 20.04 WITHIN 9H; CYCLE 2/20.01 - 20.20; ONBOARD ACQ FOR 20.10; SEQ 20.04 - 20.10 NO GAP; AT 30-SEP-92 04 01 +/- 1M; ONBOARD ACQ FOR 20.20; SEQ 20.14 - 20.20 NO GAP; AT 30-SEP-92 10 01 +/- 1M; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F750W/F320N ------------------------------------------------------------------------------------------------------------------------------------ Target Names GSC6349-01499 01499-OFFSET GSC6349-01365 01499-BACKGROUND ------------------------------------------------------------------------------------------------------------------------------------