Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 1086c Report Date: 09-May-96:16:08 Version: ********** Check-in Date: ********** 1.Proposal Title: DO NEPTUNE AND PLUTO HAVE RINGS? ------------------------------------------------------------------------------------ 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 The origin of planetary ring systems remains unknown. One common property of the known ringed planets--Jupiter, Saturn, and Uranus--is that each possesses a regular satellite system, which would point to a close connection between the formation of rings and satellites. However, the dynamical lifetimes of several important features in Saturn's are short, which would lead to the conclusion that these rings are young. Continuing this line of reasoning, one would conclude that rings are not formed concurrently with planets--perhaps the formation of rings depends on encounters of planets with small bodies, or other random events: ring systems come and go. The discovery of ring systems around Neptune and/or Pluto would shift opinion toward this latter view, while the lack of detectable rings would greatly strengthen their apparent connection with regular satellite systems. The August, 1989 Voyager encounter with Neptune discovered complete rings with shepherd satellites, and perhaps ring arcs around Neptune. We propose to further probe the structure of the system of rings and ring arcs around Neptune, to determine the dynamical processes which could create rings as well as ring arcs, and to search for rings around Pluto. To achieve this, we will use occultations, which are most sensitive to (possibly dark) material clumped into narrow rings. Revision History: Received on RPS 9/1/89; Added to SCCS 9/5/89 Updated to V2 prop. instr.; RPSS V7.2 local & remote - SALM 9/6/89; ------------------------------------------------------------------------------------ 8. Scientific Key Words: NEPTUNE, PLUTO, PLANETARY RINGS, OCCULTATIONS, RING IMAGING ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 2.00 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. Real Time obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 1086c PI: Robert C. Bless Proposal Title: DO NEPTUNE AND PLUTO HAVE RINGS? ------------------------------------------------------------------------------------ 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. Our ring search, for both Neptune and Pluto, will consist of occultations of opportunity, chosen to probe the equatorial plane of the planet (where rings are most likely to be). We plan to identify those occultations of sufficient signal- to-noise ratio to achieve the goals outlined in Section 2. Each observation will require (i) an onboard acquisition, (ii) a scan of about 10 to 20 arcseconds along the track that the object will follow relative to the occulting body, 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 require 40 minutes for Pluto and 50 minutes for Neptune. Cycle 1: all predicted occultations. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. For occultations, we can achieve a much better signal-to-noise ratio than would be possible from the ground for the following reasons: (i) the greatly improved photometric stability of ST photometry; (ii) our ability to reject background light from the occulting object by employing small focal plane apertures; and (iii) the absence of scintillation noise, which has strong components at frequencies comparable to the occultation timescale. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. A prior scan over 10 - 20 arc-seconds 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 DEC5000 belonging to the planetary astronomy group. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Data reduction and analysis will be supported on computer facilities at MIT. ------------------------------------------------------------------------------------ 13. Ring systems around Pluto will be searched for and the ring system around Neptune will be probed by stellar occultation observations with the HSP. The presence or absence of ring systems around these planets will be indicative of whether regular satellite systems are necessary for the formation of planetary rings. Page 3 ------------------------------------------------------------------------------------ 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 = 1086c [ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 10 P17 STAR TO BE OCCULTED BY RA = 15H 31M 43.184S +/- J2000 BKG 1 B = 14.3 +/- 0.1 PLUTO. 0.2", 2 V = 13.5 +/- 0.1 CLOSE APPROACH AT 21- DEC = -3D 21' 47.54" +/- 3 R = 13.1 +/- 0.1 MAY-92:06:17 0.2" 4 I = 12.6 +/- 0.1 Comments: POSREF = AMANDA. STAR POSITION WILL BE UPDATED BEFORE OBSERVATION IS PERFORMED. CONTACT: AMANDA BOSH, MIT. ------------------------------------------------------------------------------------------------------------------------------------ 12 P17-OFFSET OFFSET STAR TO BE RA = 15H 31M 40.129S +/- J2000 1 R = 16.2 +/- 0.2 STAR-1532- ACQUIRED 0.2", 0322 DEC = -3D 22' 29.69" +/- 0.2", Comments: POSREF = AMANDA. STAR POSITION WILL BE UPDATED BEFORE OBSERVATION IS PERFORMED. CONTACT: AMANDA BOSH, MIT. ------------------------------------------------------------------------------------------------------------------------------------ TARGET LIST b)Solar System Targets ID = 1086c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 15 | TARGET NAME: PLUTO-BACKGROUND ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: OFFSET PLUTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = PLUTO, ACQ = 0.1 | TYPE = POS_ANGLE, | RAD = 22.0, | ANG = 93.343, | REF = NORTH | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ REF | DATA | COMMENTS | | | | POSREF = AMANDA. FOR USE IN A SCAN | | OF BACKGROUND LEVELS ALONG THE PATH | | OF THE OCCULTED STAR. | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 16 | TARGET NAME: PLUTO-CENTER ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET PLUTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = PLUTO, ACQ = 0.1 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ REF | DATA | COMMENTS | | 1 |V = 13.8 +/- 0.5 | POSREF = AMANDA. ACQUISITION TARGET | | FOR PLUTO-BACKGROUND. | ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 1086c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 6.1 DEFINE # HSP/ SPLIT 1.0 F750W/ # 1 1M 1 1 CRIT OBS OCC PMT/ F320N GUID TOL 0.007" VIS Comments: USE FINE LOCK IF BRIGHT ENOUGH GUIDE STARS CAN BE FOUND. IF NOT, COARSE TRACK IS ACCEPTABLE. ------------------------------------------------------------------------------------------------------------------------------------ 6.2 DEFINE # HSP/ ACQ 1 300S 1 1 GUID TOL 0.007" ONBRD- VIS ACQ Comments: USE FINE LOCK FOR GUIDE STAR ACQ IF BRIGHT ENOUGH GUIDE STARS CAN BE FOUND. IF NOT, COARSE TRACK IS ACCEPTABLE. ------------------------------------------------------------------------------------------------------------------------------------ 6.3 DEFINE # HSP/ SPLIT 1.0 F750W/ # 1 1S 1 1 SPATIAL SCAN BACK- PMT/ F320N GUID TOL 0.007" SCAN VIS Comments: USE FINE LOCK IF BRIGHT ENOUGH GUIDE STARS CAN BE FOUND. IF NOT, COARSE TRACK IS ACCEPTABLE. ------------------------------------------------------------------------------------------------------------------------------------ 10 USE PLUTO- ONBOARD ACQ FOR ONBRD- CENTER 10.01 ACQ SEQ 10.00 - 10.01 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 10.01 USE PLUTO- SAMPLE- X400 SEQ 10.01 - 10.03 BACK- BACKGROUND TIME=0.01 GROUP 10.01 - SCAN DATA-FORMAT=ALL 10.04 WITHIN 12H PRECISION=HIGH VIS-ANALOG=10 PMT-ANALOG=10 Comments: EXECUTE 10.01 - 10.04 AS CLOSE TO TIME OF OCCULTATION AS IS SCHEDULABLE. MAY BE PERFORMED BEFORE OR AFTER 10.09; ------------------------------------------------------------------------------------------------------------------------------------ 10.02 USE PLUTO- SAMPLE- X1200 BACK- BACKGROUND TIME=0.025 SCAN DATA-FORMAT=ALL PRECISION=HIGH VIS-ANALOG=10 PMT-ANALOG=10 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 1086c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10.03 USE PLUTO- SAMPLE- X400 BACK- BACKGROUND TIME=0.01 SCAN DATA-FORMAT=ALL PRECISION=HIGH VIS-ANALOG=10 PMT-ANALOG=10 ------------------------------------------------------------------------------------------------------------------------------------ 10.04 USE P17-OFFSET ONBOARD ACQ FOR ONBRD- 10.09 ACQ SEQ 10.04 - 10.09 NO GAP CYCLE 1 / 10.00 - 10.09 ------------------------------------------------------------------------------------------------------------------------------------ 10.09 USE OCC P17 SAMPLE- X20 AT 21-MAY-92:05:58 TIME=0.05 +/- 1M DATA-FORMAT=ALL PRECISION=HIGH VIS-ANALOG=10 PMT-ANALOG=10 Comments: END EXPOSURE AT 21-MAY-92:06:37 MAKE EXPOSURE AS LONG AS POSSIBLE IN ONE ORBIT UP TO 40 MINUTES. ------------------------------------------------------------------------------------------------------------------------------------ Scan Paramters Form Proposal ID: 1086c [ 8] ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 1 Exposure Logsheet lines: 10.01, 10.03 FGS Scan: CONTINUOUS Dwell Only: dwell points/line: 0 Seconds per dwell: 0.00 Scan width (arc-secs): 0.0000 Scan length (arc-secs): 35.0000 Angle between sides (degrees) 90.00 Number of lines: 1 Scan rate (arc-sec/sec): 0.0500 PA of first scan line (degrees) 279.343 Scan frame (CEL or S/C): CEL Length Offset (arc-sec): 0. Width Offset (arc-sec): 0. ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 2 Exposure Logsheet lines: 10.02 FGS Scan: CONTINUOUS Dwell Only: dwell points/line: 0 Seconds per dwell: 0.00 Scan width (arc-secs): 1.0000 Scan length (arc-secs): 35.0000 Angle between sides (degrees) 90.00 Number of lines: 3 Scan rate (arc-sec/sec): 0.0500 PA of first scan line (degrees) 279.343 Scan frame (CEL or S/C): CEL Length Offset (arc-sec): 0. Width Offset (arc-sec): 0.5000 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 1086c [ 9] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HSP/PMT/VIS HSP/VIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes SPLIT ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMPLE-TIME DATA-FORMAT PRECISION VIS-ANALOG PMT-ANALOG ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GTO/HSP ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 2.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CRIT OBS; GUID TOL 0.007"; SPATIAL SCAN; ONBOARD ACQ FOR 10.01; SEQ 10.00 - 10.01 NO GAP; SEQ 10.01 - 10.03; GROUP 10.01 - 10.04 WITHIN 12H; ONBOARD ACQ FOR 10.09; SEQ 10.04 - 10.09 NO GAP; CYCLE 1 / 10.00 - 10.09; AT 21-MAY-92 05 58 +/- 1M; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F750W/F320N ------------------------------------------------------------------------------------------------------------------------------------ Target Names P17 P17-OFFSET STAR-1532-0322 PLUTO-BACKGROUND PLUTO-CENTER ------------------------------------------------------------------------------------------------------------------------------------