Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 1081c Report Date: 09-May-96:16:07 Version: ********** Check-in Date: ********** 1.Proposal Title: SATURN RING DYNAMICS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID SOLAR SYSTEM GTO/HSP 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: Received on RPS 9/1/89; Added to SCCS 9/5/89 RPSS V7.2 local & remote; fixed up small syntax errors - SALM 9/5/89 Updated for cycle 1 -- amanda bosh (MIT) 28 Sept 89 asb @ MIT 19 Mar 1990: Updated cycle 1 targets; SPATIAL SCANs, GUID TOL changes etc. - asb@MIT 23May90; Small logic errors fixed-- BJW 7/9/90; revised changes to SEQ--BJW 7/31/90; Change cycle 0 to cycle 8 on line 110.040--BJW 11/28/90; Changes to observations/targets--amanda; Split proposal by cycle--BJW 5/2/91; Added reference for target positions--BJW 7/18/91; ------------------------------------------------------------------------------------ 8. Scientific Key Words: SATURN'S RINGS, OCCULTATIONS, RING DYNAMICS ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 22.00 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 1081c PI: Robert C. Bless Proposal Title: SATURN RING DYNAMICS ------------------------------------------------------------------------------------ 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) external "darks", taken on a dark region of sky as a calibration source, (ii) a scan of about 30-40 arcseconds along the track that the object will follow relative to Saturn's rings, (iii) a set of two sequential onboard acquisitions; and (iv) 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 least a few events, it would be important to observe occultations by the same features on both sides of the planet. All cycles. ------------------------------------------------------------------------------------ 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 DEC 5000 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. Page 3 ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Data reduction and analysis will be supported on computer facilities at MIT. ------------------------------------------------------------------------------------ 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 = 1081c [ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 11 GSC6323- STAR TO BE OCCULTED BY PLATE-ID = 04O8, J2000 BKG 1 V = 12.47 +/- 0.59 01396 SATURN. RA = 20H 10M 30.352S +/- CLOSE APPROACH AT 2-OCT 0.4", -91:04:57 DEC = -20D 36' 47.593" +/- 0.4", Comments: COORDS FROM GUIDE STAR CATALOG SOLAR ELONG E113D ------------------------------------------------------------------------------------------------------------------------------------ 12 GSC6327- OFFSET TARGET FOR PLATE-ID = 04O8, J2000 BKG 1 V = 15.50 +/- 0.61 00161 GSC6323-01396 RA = 20H 10M 32.868S +/- 0.4", DEC = -20D 38' 14.964" +/- 0.4", Comments: COORDS FROM GUIDE STAR CATALOG SOLAR ELONG E113D ------------------------------------------------------------------------------------------------------------------------------------ 13 DARK-PMT RA = 16H 27M 11.0S +/- 0.1S, J2000 DEC = -24D 19' 14.0" +/- 0.1S, Comments: DARK PORTION OF THE SKY FOR PMT DARK MEASUREMENT ------------------------------------------------------------------------------------------------------------------------------------ TARGET LIST b)Solar System Targets ID = 1081c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 18 | TARGET NAME: SATURN-BACKGROUND ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: OFFSET SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = SATURN | TYPE = POS_ANGLE, | RAD = 11.5, | ANG = 219.7, | REF = NORTH | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ REF | DATA | COMMENTS | | 1 |V = 0.7 +/- 0.5 | FOR USE IN A SCAN OF BACKGROUND | | LEVELS ALONG THE PATH OF THE | | OCCULTED STAR | ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 1081c [ 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 120S 1 1 GUID TOL 0.007" 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. ------------------------------------------------------------------------------------------------------------------------------------ 5 DEFINE # HSP/ SPLIT 1.0 F750W/ SAMPLE- 1 5M 1 1 GUID TOL 0.02" EXT- PMT/ F320N TIME=0.15 DARK VIS DATA-FORMAT=ALL PRECISION=HIGH ANALOG- SCALE=1000 Comments: EXTERNAL STANDARD CALIBRATION. USE COARSE TRACK FOR TRACKING. HIGH ACCURACY NOT NEEDED, WANT TO SAVE TIME. ------------------------------------------------------------------------------------------------------------------------------------ 6 DEFINE # HSP/ SPLIT 1.0 F750W/ # 1 1S 1 1 SPATIAL SCAN BACK- PMT/ F320N DATA-FORMAT=ALL SINGLE-EXP SCAN VIS ANALOG- GUID TOL 0.007" SCALE=1000 PRECISION=HIGH Comments: USE FINE LOCK FOR OFFSET TARGET ACQ IF BRIGHT ENOUGH GUIDE STARS CAN BE FOUND. IF NOT, COARSE TRACK IS ACCEPTABLE. ------------------------------------------------------------------------------------------------------------------------------------ 7 DEFINE # HSP/ SPLIT 1.0 F750W/ SAMPLE- 1 1M 1 1 CRIT OBS RING- PMT/ F320N TIME=0.15 GUID TOL 0.007" OCC VIS PRECISION=HIGH DATA-FORMAT=ALL ANALOG- SCALE=1000 Comments: USE FINE LOCK FOR OFFSET TARGET ACQ IF BRIGHT ENOUGH GUIDE STARS CAN BE FOUND. IF NOT, COARSE TRACK IS ACCEPTABLE. HSP09A (SV TEST) MUST BE COMPLETED SUCCESSFULLY BEFORE THESE OBSERVATIONS. ------------------------------------------------------------------------------------------------------------------------------------ 110 USE EXT DARK-PMT GROUP 110.000 - -DARK 110.113 WITHIN 3D CYCLE 0/110.000 - 110.280 ------------------------------------------------------------------------------------------------------------------------------------ 110.01 USE SATURN- SAMPLE- X174 SEQ 110.01 - BACK- BACKGROUND TIME=0.01 110.03 SCAN GROUP 110.01 - 110.04 WITHIN 1D ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 1081c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 110.02 USE SATURN- SAMPLE- X868 BACK- BACKGROUND TIME=0.15 SCAN ------------------------------------------------------------------------------------------------------------------------------------ 110.03 USE SATURN- SAMPLE- X174 BACK- BACKGROUND TIME=0.01 SCAN ------------------------------------------------------------------------------------------------------------------------------------ 110.04 USE GSC6327- ONBOARD ACQ FOR ONBRD- 00161 110.101 - 110.113 ACQ SEQ 110.04 - 110.113 NO GAP Comments: THIS OCCULTATION OCCURS OVER SEVEN DAYS. IT IS BEING BROKEN INTO SEVERAL PARTS, AND ONLY CLASSICAL RING DATA WILL BE COLLECTED. ------------------------------------------------------------------------------------------------------------------------------------ 110.1 USE GSC6323- X39 AT 2-OCT-91:19:30 RING- 01396 +/- 30M OCC Comments: END EXPOSURE AT 3-OCT-91:15:00. TIME_PER_EXP IS SHORTER THAN THAT CALCULATED FROM START-STOP TIMES TO ACCOUNT FOR EARTH OCCULTATIONS. ------------------------------------------------------------------------------------------------------------------------------------ 110.1 USE GSC6323- X40 RING- 01396 OCC ------------------------------------------------------------------------------------------------------------------------------------ 110.1 USE GSC6323- X17 RING- 01396 OCC ------------------------------------------------------------------------------------------------------------------------------------ 110.1 USE GSC6323- X18 RING- 01396 OCC ------------------------------------------------------------------------------------------------------------------------------------ 110.1 USE GSC6323- X22 RING- 01396 OCC ------------------------------------------------------------------------------------------------------------------------------------ 110.1 USE GSC6323- X28 RING- 01396 OCC ------------------------------------------------------------------------------------------------------------------------------------ 110.1 USE GSC6323- X34 RING- 01396 OCC ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 1081c [ 8] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 110.1 USE GSC6323- X40 RING- 01396 OCC ------------------------------------------------------------------------------------------------------------------------------------ 110.1 USE GSC6323- X40 RING- 01396 OCC ------------------------------------------------------------------------------------------------------------------------------------ 110.11 USE GSC6323- X40 RING- 01396 OCC ------------------------------------------------------------------------------------------------------------------------------------ 110.111 USE GSC6323- X40 RING- 01396 OCC ------------------------------------------------------------------------------------------------------------------------------------ 110.112 USE GSC6323- X40 RING- 01396 OCC ------------------------------------------------------------------------------------------------------------------------------------ 110.113 USE GSC6323- X40 RING- 01396 OCC ------------------------------------------------------------------------------------------------------------------------------------ 110.26 USE SATURN- SAMPLE- X174 SEQ 110.26 - BACK- BACKGROUND TIME=0.01 110.28 SCAN GROUP 110.101 - 110.28 WITHIN 1D ------------------------------------------------------------------------------------------------------------------------------------ 110.27 USE SATURN- SAMPLE- X868 BACK- BACKGROUND TIME=0.15 SCAN ------------------------------------------------------------------------------------------------------------------------------------ 110.28 USE SATURN- SAMPLE- X174 BACK- BACKGROUND TIME=0.01 SCAN ------------------------------------------------------------------------------------------------------------------------------------ Scan Paramters Form Proposal ID: 1081c [ 9] ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 1 Exposure Logsheet lines: 110.01, 110.03, 110.2 FGS Scan: CONTINUOUS Dwell Only: dwell points/line: 0 Seconds per dwell: 0.00 Scan width (arc-secs): 0.0000 Scan length (arc-secs): 34.7000 Angle between sides (degrees) 90.00 Number of lines: 1 Scan rate (arc-sec/sec): 0.2000 PA of first scan line (degrees) 70.300 Scan frame (CEL or S/C): CEL Length Offset (arc-sec): 0. Width Offset (arc-sec): 0. ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 2 Exposure Logsheet lines: 110.02, 110.27 FGS Scan: CONTINUOUS Dwell Only: dwell points/line: 0 Seconds per dwell: 0.00 Scan width (arc-secs): 3.0000 Scan length (arc-secs): 34.7000 Angle between sides (degrees) 90.00 Number of lines: 5 Scan rate (arc-sec/sec): 0.2000 PA of first scan line (degrees) 70.300 Scan frame (CEL or S/C): CEL Length Offset (arc-sec): 0. Width Offset (arc-sec): 1.5000 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 1081c [ 10] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HSP/VIS HSP/PMT/VIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ SPLIT ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMPLE-TIME=0.15 DATA-FORMAT PRECISION ANALOG-SCALE PRECISION=HIGH DATA-FORMAT=ALL SAMPLE-TIME ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GTO/HSP ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 22.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GUID TOL 0.007"; GUID TOL 0.02"; SPATIAL SCAN SINGLE-EXP; CRIT OBS; GROUP 110.000 - 110.113 WITHIN 3D; CYCLE 0/110.000 - 110.280; SEQ 110.01 - 110.03; GROUP 110.01 - 110.04 WITHIN 1D; ONBOARD ACQ FOR 110.101 - 110.113; SEQ 110.04 - 110.113 NO GAP; AT 2-OCT-91 19 30 +/- 30M; SEQ 110.26 - 110.28; GROUP 110.101 - 110.28 WITHIN 1D; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F750W/F320N ------------------------------------------------------------------------------------------------------------------------------------ Target Names GSC6323-01396 GSC6327-00161 DARK-PMT SATURN-BACKGROUND ------------------------------------------------------------------------------------------------------------------------------------