! File: 1086C.PROP ! Database: PEPDB ! Date: 16-FEB-1994:01:10:06 coverpage: title_1: DO NEPTUNE AND PLUTO HAVE RINGS? sci_cat: SOLAR SYSTEM proposal_for: GTO/HSP pi_fname: ROBERT pi_mi: C. pi_lname: BLESS pi_inst: WISCONSIN, UNIVERSITY OF pi_country: USA pi_phone: 608-262-1715 keywords_1: NEPTUNE, PLUTO, PLANETARY RINGS, OCCULTATIONS, RING keywords_2: IMAGING hours_pri: 2.00 num_pri: 2 realtime: Y time_crit: Y ! end of coverpage abstract: line_1: The origin of planetary ring systems remains unknown. One common property of line_2: the known ringed planets--Jupiter, Saturn, and Uranus--is that each possesses a line_3: regular satellite system, which would point to a close connection between the line_4: formation of rings and satellites. However, the dynamical lifetimes of several line_5: important features in Saturn's are short, which would lead to the conclusion line_6: that these rings are young. Continuing this line of reasoning, one would line_7: conclude that rings are not formed concurrently with planets--perhaps the line_8: formation of rings depends on encounters of planets with small bodies, or other line_9: random events: ring systems come and go. The discovery of ring systems around line_10: Neptune and/or Pluto would shift opinion toward this latter view, while the line_11: lack of detectable rings would greatly strengthen their apparent connection line_12: with regular satellite systems. The August, 1989 Voyager encounter line_13: with Neptune discovered complete rings with shepherd satellites, and line_14: perhaps ring arcs around Neptune. We propose to further probe the structure line_15: of the system of rings and ring arcs around Neptune, to determine the line_16: dynamical processes which could create rings as well as ring arcs, and to line_17: search for rings around Pluto. To achieve this, we will use occultations, line_18: which are most sensitive to (possibly dark) material clumped into narrow rings. line_19: Revision History: Received on RPS 9/1/89; Added to SCCS 9/5/89 line_20: Updated to V2 prop. instr.; RPSS V7.2 local & remote - SALM 9/6/89; ! ! end of abstract general_form_proposers: lname: ROBINSON fname: EDWARD mi: L. inst: TEXAS, UNIVERSITY OF country: USA ! lname: BLESS fname: ROBERT mi: C. inst: WISCONSIN, UNIVERSITY OF country: USA ! lname: VAN CITTERS fname: G. mi: W. inst: NATIONAL SCIENCE FOUNDATION country: USA ! lname: DOLAN fname: JOSEPH mi: F. inst: NASA, GODDARD SPACE FLIGHT CENTER country: USA ! lname: WHITE fname: RICHARD mi: L. inst: SPACE TELESCOPE SCIENCE INSTITUTE country: USA ! lname: ELLIOT fname: JAMES mi: L. inst: MASSACHUSETTS INSTITUTE OF TECHNOLOGY country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: Our ring search, for both Neptune and Pluto, will consist of occultations of line_2: opportunity, chosen to probe the equatorial plane of the planet (where rings line_3: are most likely to be). line_4: We plan to identify those occultations of sufficient signal-to-noise ratio to line_5: achieve the goals outlined in Section 2. Each observation will require (i) line_6: an onboard acquisition, (ii) a scan of about 10 to 20 arcseconds line_7: along the track that the object will follow relative to the occulting line_8: body, and (iii) a time series run on the object with whatever filter- line_9: aperture combination that is chosen for the observation. For some line_10: occultations to be observed in the far UV, prior multi-filter photometry line_11: of the object will be necessary in order to determine the most line_12: appropriate filter to use for the occultation. The default filter set is line_13: F750W/F320N. For now, we shall assume that the calibration and line_14: observation time will require 40 minutes for Pluto and 50 minutes for Neptune. line_15: Cycle 1: all predicted occultations. ! question: 4 section: 1 line_1: For occultations, we can achieve a much better signal-to-noise ratio than line_2: would be possible from the ground for the following reasons: (i) the greatly line_3: improved photometric stability of ST photometry; (ii) our ability to reject line_4: background light from the occulting object by employing small focal plane line_5: apertures; and (iii) the absence of scintillation noise, which has strong line_6: components at frequencies comparable to the occultation timescale. ! question: 6 section: 1 line_1: A prior scan over 10 - 20 arc-seconds is needed to map the scattered light line_2: field, which is needed for the data reduction. ! question: 7 section: 1 line_1: Data will be reduced and analyzed at MIT with the DEC5000 belonging to the line_2: planetary astronomy group. ! question: 10 section: 1 line_1: Data reduction and analysis will be supported on computer facilities line_2: at MIT. ! question: 13 section: 1 line_1: Ring systems around Pluto will be searched for and the ring system around line_2: Neptune will be probed by stellar occultation observations with the HSP. line_3: The presence or absence of ring systems around these planets will be line_4: indicative of whether regular satellite systems are necessary for the line_5: formation of planetary rings. ! !end of general form text general_form_address: lname: BLESS fname: ROBERT mi: C. category: PI inst: UNIVERSITY OF WISCONSIN addr_1: DEPARTMENT OF ASTRONOMY city: MADISON state: WI zip: 53706 country: USA phone: 608-262-1715 ! lname: ELLIOT fname: JAMES mi: L. category: CON inst: MASSACHUSETTS INSTITUTE OF TECHNOLOGY addr_1: BLDG. 54-422 city: CAMBRIDGE state: MA zip: 02139 country: USA phone: 617-253-6308 telex: 921473 MIT CAM ! ! end of general_form_address records fixed_targets: targnum: 10 name_1: P17 descr_1: STAR TO BE OCCULTED BY PLUTO. descr_2: CLOSE APPROACH AT 21-MAY-92:06:17 pos_1: RA = 15H 31M 43.184S +/- 0.2", pos_2: DEC = -3D 21' 47.54" +/- 0.2" equinox: J2000 acqpr_1: BKG comment_1: POSREF = AMANDA. comment_2: STAR POSITION WILL BE UPDATED comment_3: BEFORE OBSERVATION IS PERFORMED. comment_4: CONTACT: AMANDA BOSH, MIT. fluxnum_1: 1 fluxval_1: B = 14.3 +/- 0.1 fluxnum_2: 2 fluxval_2: V = 13.5 +/- 0.1 fluxnum_3: 3 fluxval_3: R = 13.1 +/- 0.1 fluxnum_4: 4 fluxval_4: I = 12.6 +/- 0.1 ! targnum: 12 name_1: P17-OFFSET name_2: STAR-1532-0322 descr_1: OFFSET STAR TO BE ACQUIRED pos_1: RA = 15H 31M 40.129S +/- 0.2", pos_2: DEC = -3D 22' 29.69" +/- 0.2", equinox: J2000 comment_1: POSREF = AMANDA. comment_2: STAR POSITION WILL BE UPDATED comment_3: BEFORE OBSERVATION IS PERFORMED. comment_4: CONTACT: AMANDA BOSH, MIT. fluxnum_1: 1 fluxval_1: R = 16.2 +/- 0.2 ! ! end of fixed targets solar_system_targets: targnum: 15 name_1: PLUTO-BACKGROUND descr_1: OFFSET PLUTO lev1_1: STD = PLUTO, ACQ = 0.1 lev2_1: TYPE = POS_ANGLE, lev2_2: RAD = 22.0, lev2_3: ANG = 93.343, lev2_4: REF = NORTH comment_1: POSREF = AMANDA. comment_2: FOR USE IN A SCAN OF comment_3: BACKGROUND LEVELS ALONG comment_4: THE PATH OF THE OCCULTED STAR. ! targnum: 16 name_1: PLUTO-CENTER descr_1: PLANET PLUTO lev1_1: STD = PLUTO, ACQ = 0.1 comment_1: POSREF = AMANDA. comment_2: ACQUISITION TARGET FOR comment_3: PLUTO-BACKGROUND. fluxnum_1: 1 fluxval_1: V = 13.8 +/- 0.5 ! ! end of solar system targets ! No generic target records found exposure_logsheet: linenum: 6.100 sequence_1: DEFINE sequence_2: OCC targname: # config: HSP/PMT/VIS opmode: SPLIT aperture: 1.0 sp_element: F750W/F320N num_exp: 1 time_per_exp: 1M fluxnum_1: 1 priority: 1 param_1: # req_1: CRIT OBS; req_2: GUID TOL 0.007"; comment_1: USE FINE LOCK IF BRIGHT ENOUGH comment_2: GUIDE STARS CAN BE FOUND. IF NOT, comment_3: COARSE TRACK IS ACCEPTABLE. ! linenum: 6.200 sequence_1: DEFINE sequence_2: ONBRD-ACQ targname: # config: HSP/VIS opmode: ACQ num_exp: 1 time_per_exp: 300S fluxnum_1: 1 priority: 1 req_1: GUID TOL 0.007"; comment_1: USE FINE LOCK FOR GUIDE STAR ACQ IF comment_2: BRIGHT ENOUGH GUIDE STARS CAN BE comment_3: FOUND. IF NOT, COARSE TRACK IS comment_4: ACCEPTABLE. ! linenum: 6.300 sequence_1: DEFINE sequence_2: BACK-SCAN targname: # config: HSP/PMT/VIS opmode: SPLIT aperture: 1.0 sp_element: F750W/F320N num_exp: 1 time_per_exp: 1S fluxnum_1: 1 priority: 1 param_1: # req_1: SPATIAL SCAN; req_2: GUID TOL 0.007"; comment_1: USE FINE LOCK IF BRIGHT ENOUGH comment_2: GUIDE STARS CAN BE FOUND. IF comment_3: NOT, COARSE TRACK IS ACCEPTABLE. ! linenum: 10.000 sequence_1: USE sequence_2: ONBRD-ACQ targname: PLUTO-CENTER req_1: ONBOARD ACQ FOR 10.01; req_2: SEQ 10.00 - 10.01 NO GAP; ! linenum: 10.010 sequence_1: USE sequence_2: BACK-SCAN targname: PLUTO-BACKGROUND time_per_exp: X400 param_1: SAMPLE-TIME = 0.01, param_2: DATA-FORMAT = ALL, param_3: PRECISION = HIGH, param_4: VIS-ANALOG = 10, param_5: PMT-ANALOG = 10, req_1: SEQ 10.01 - 10.03; req_2: GROUP 10.01 - 10.04 WITHIN 12H; comment_1: EXECUTE 10.01 - 10.04 AS CLOSE comment_2: TO TIME OF OCCULTATION AS IS comment_3: SCHEDULABLE. MAY BE PERFORMED comment_4: BEFORE OR AFTER 10.09; ! linenum: 10.020 sequence_1: USE sequence_2: BACK-SCAN targname: PLUTO-BACKGROUND time_per_exp: X1200 param_1: SAMPLE-TIME = 0.025, param_2: DATA-FORMAT = ALL, param_3: PRECISION = HIGH, param_4: VIS-ANALOG = 10, param_5: PMT-ANALOG = 10, ! linenum: 10.030 sequence_1: USE sequence_2: BACK-SCAN targname: PLUTO-BACKGROUND time_per_exp: X400 param_1: SAMPLE-TIME = 0.01, param_2: DATA-FORMAT = ALL, param_3: PRECISION = HIGH, param_4: VIS-ANALOG = 10, param_5: PMT-ANALOG = 10, ! linenum: 10.040 sequence_1: USE sequence_2: ONBRD-ACQ targname: P17-OFFSET req_1: ONBOARD ACQ FOR 10.09; req_2: SEQ 10.04 - 10.09 NO GAP; req_3: CYCLE 1 / 10.00 - 10.09; ! linenum: 10.090 sequence_1: USE sequence_2: OCC targname: P17 time_per_exp: X20 param_1: SAMPLE-TIME = 0.05, param_2: DATA-FORMAT = ALL, param_3: PRECISION = HIGH, param_4: VIS-ANALOG = 10, param_5: PMT-ANALOG = 10, req_1: AT 21-MAY-92:05:58 +/- 1M; comment_1: END EXPOSURE AT 21-MAY-92:06:37 comment_2: MAKE EXPOSURE AS LONG AS POSSIBLE IN comment_3: ONE ORBIT UP TO 40 MINUTES. ! ! end of exposure logsheet scan_data: line_list: 10.01, 10.03 fgs_scan: cont_dwell: C dwell_pnts: 0 dwell_secs: 0.00 scan_width: 0.0000 scan_length: 35.0000 sides_angle: 90.0000 number_lines: 1 scan_rate: 0.0500 first_line_pa: 279.3430 scan_frame: CEL len_offset: 0. wid_offset: 0. ! line_list: 10.02 fgs_scan: cont_dwell: C dwell_pnts: 0 dwell_secs: 0.00 scan_width: 1.0000 scan_length: 35.0000 sides_angle: 90.0000 number_lines: 3 scan_rate: 0.0500 first_line_pa: 279.3430 scan_frame: CEL len_offset: 0. wid_offset: 0.5 ! ! end of scan data