! File: 1082C.PROP ! Database: PEPDB ! Date: 16-FEB-1994:00:59:07 coverpage: title_1: HELIUM ABUNDANCE IN JOVIAN PLANET UPPER ATMOSPHERES 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: JOVIAN PLANETS, OCCULTATIONS, UPPER ATMOSPHERES, keywords_2: HELIUM ABUNDANCES hours_pri: 6.00 num_pri: 16 hsp: Y time_crit: Y ! end of coverpage abstract: line_1: The large masses of the Jovian planets make it line_2: likely that they have retained their primordial line_3: abundance of material accreted from the solar line_4: nebula. The helium abundance in the upper line_5: atmospheres of these planets reflects the primordial line_6: abundance and the structural evolution of the line_7: planet. We propose to determine the Helium fraction line_8: in the upper atmosphere of each Jovian planet by line_9: measuring the ratio of the refractivities of its line_10: atmosphere for two wavelengths during stellar line_11: occultations. Revision History: Updated for Cycle 2 line_12: submission--ASB 3/20/92; ! ! 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: We plan to use the ST orbit parameters and the line_2: ephemerides of the Jovian planets to identify those line_3: occultations of sufficient signal-to-noise ratio to line_4: achieve the goals outlined in Section 2. The line_5: observation sequence is as follows: 1) Obtain a line_6: WFPC image to determine the exact occultation line_7: parameters. 2) Acquire occultation candidate using line_8: onboard acquisition mode. 3) Scan along the track line_9: that the star will follow relative to the planet in line_10: order to determine the planetary contribution to the line_11: background. 4) Start continous series of 10ms line_12: integrations 10 arcseconds prior to the predicted line_13: immersion time (for Jupiter). The occultation line_14: observation will require simple tracking on the star line_15: before atmosphere immersion, complex tracking on the line_16: stellar image as it moves along the planetary limb, line_17: and simple tracking after atmosphere emersion. This line_18: sequence of integrations must be continuous. 6) line_19: Scan along the track that the star will follow line_20: relative to the planet 7) Monitor dark current on ! question: 4 section: 1 line_1: We can achieve a much better signal-to-noise ratio line_2: for determining the helium abundance from these line_3: occultations than would be possible from the ground line_4: for the following reasons: (i) the lower level of line_5: background scattered light seen by the ST; (ii) our line_6: ability to reject background light by employing line_7: small focal plane apertures; (iii) the absence of line_8: scintillation noise, which has strong components at line_9: frequencies comparable to the occultation timescale; line_10: and (iv) the much greater span of wavelengths that line_11: can be covered--well into the UV for occultations of line_12: stars of early spectral type. ! question: 5 section: 1 line_1: Aquisition of the object near the planet may be difficult. line_2: Tracking the occulted star in some cases will require a real line_3: time update, due to its complicated path caused by refraction line_4: in the occulting planet's atmosphere and the uncertainties in line_5: predicting the ST orbit. ! question: 6 section: 1 line_1: A prior scan of the path the star will take through line_2: the planetary atmosphere is needed to map the line_3: scattered light field (necessary for the data line_4: reduction). Once the star is in the beamsplitter line_5: aperture and is being occulted by the planet, the line_6: integration sequence must be uninterrupted as the line_7: data are time-critical. ! question: 7 section: 1 line_1: Data will be reduced and analyzed at MIT with the line_2: VAX 11-750 belonging to the planetary astronomy line_3: group. ! question: 10 section: 1 line_1: Data reduction and analysis will be supported on line_2: computer facilities at MIT. ! question: 13 section: 1 line_1: The helium abundances in the upper atmospheres of line_2: the Jovian Planets can be obtained with the HSP line_3: by measuring the refractivities of the line_4: atmospheres at two different wavelengths during line_5: stellar occultations. The helium abundance reflects line_6: the primordial abundance and the structural line_7: evolution of the planet. ! !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 ! 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: 12 name_1: GSC5808-00138 descr_1: STAR TO BE OCCULTED BY SATURN. descr_2: CLOSE APPROACH AT 29-APR-93:20:56 pos_1: PLATE-ID = 00CT, pos_2: RA = 22H 06M 26.87S +/- 0.5", pos_3: DEC = -12D 55' 49.1" +/- 0.5", equinox: J2000 acqpr_1: BKG comment_1: STAR POSITION WILL BE UPDATED comment_2: BEFORE OBSERVATION IS PERFORMED. comment_3: CONTACT: AMANDA S. BOSH, MIT comment_4: SOLAR ELONG 71D fluxnum_1: 1 fluxval_1: V = 13.1 +/- 0.3 fluxnum_2: 2 fluxval_2: B = 13.6 +/- 0.3 fluxnum_3: 3 fluxval_3: R = 12.4 +/- 0.3 ! targnum: 13 name_1: 00138-OFFSET name_2: GSC5808-00943 descr_1: OFFSET TARGET FOR GSC5808-00138 pos_1: PLATE-ID = 00CT, pos_2: RA = 22H 06M 23.96S +/- 0.5", pos_3: DEC = -12D 56' 11.3" +/- 0.5", equinox: J2000 comment_1: STAR POSITION WILL BE UPDATED comment_2: BEFORE OBSERVATION IS PERFORMED. comment_3: CONTACT: AMANDA S. BOSH, MIT fluxnum_1: 1 fluxval_1: B = 15.2 +/- 0.6 ! ! end of fixed targets solar_system_targets: targnum: 19 name_1: 00138-BACKGROUND descr_1: OFFSET SATURN lev1_1: STD = SATURN lev2_1: TYPE = POS_ANGLE, lev2_2: RAD = 24.4, lev2_3: ANG = 68.2, lev2_4: REF = NORTH comment_1: FOR USE IN A SCAN OF comment_2: BACKGROUND LEVELS ALONG comment_3: THE PATH OF THE OCCULTED STAR ! ! end of solar system targets ! No generic target records found exposure_logsheet: linenum: 4.000 sequence_1: DEFINE sequence_2: ONBRD-ACQ targname: # config: HSP/VIS opmode: ACQ num_exp: 1 time_per_exp: 1S fluxnum_1: 1 priority: 1 ! linenum: 6.000 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; ! linenum: 7.000 sequence_1: DEFINE sequence_2: RING-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; ! linenum: 20.010 sequence_1: USE sequence_2: BACK-SCAN targname: 00138-BACKGROUND time_per_exp: X467 param_1: SAMPLE-TIME = 0.05, param_2: PRECISION = HIGH, param_3: DATA-FORMAT = ALL, param_4: PMT-ANALOG = 1000, param_5: VIS-ANALOG = 100, req_1: SEQ 20.01 - 20.03; req_3: CYCLE 2/20.01 - 20.10; ! linenum: 20.020 sequence_1: USE sequence_2: BACK-SCAN targname: 00138-BACKGROUND time_per_exp: X467 param_1: SAMPLE-TIME = 0.1, param_2: PRECISION = HIGH, param_3: DATA-FORMAT = ALL, param_4: PMT-ANALOG = 1000, param_5: VIS-ANALOG = 100, ! linenum: 20.030 sequence_1: USE sequence_2: BACK-SCAN targname: 00138-BACKGROUND time_per_exp: X467 param_1: SAMPLE-TIME = 0.05, param_2: PRECISION = HIGH, param_3: DATA-FORMAT = ALL, param_4: PMT-ANALOG = 1000, param_5: VIS-ANALOG = 100, ! linenum: 20.040 sequence_1: USE sequence_2: ONBRD-ACQ targname: 00138-OFFSET time_per_exp: X100 req_1: ONBOARD ACQ FOR 20.10; req_2: SEQ 20.04 - 20.10 NO GAP; req_3: GROUP 20.01 - 20.04 WITHIN 9H; ! linenum: 20.100 sequence_1: USE sequence_2: RING-OCC targname: GSC5808-00138 time_per_exp: X100 param_1: SAMPLE-TIME = 0.1, param_2: PRECISION = HIGH, param_3: DATA-FORMAT = ALL, param_4: PMT-ANALOG = 1000, param_5: VIS-ANALOG = 100, req_1: AT 29-APR-93:19:41 +/- 6M; comment_1: END EXPOSURE AT 29-APR-93:22:25.; comment_2: +/- 1M TO AVOID ABSOLUTE COMMANDING ; comment_3: ORIGINAL +/- 1M SHOULD BE RESPECTED ; comment_4: IN SCHEDULING. ! ! end of exposure logsheet scan_data: line_list: 20.01, 20.03 fgs_scan: cont_dwell: C dwell_pnts: 0 dwell_secs: 0.00 scan_width: 0.0000 scan_length: 57.5000 sides_angle: 90.0000 number_lines: 1 scan_rate: 0.0750 first_line_pa: 252.2000 scan_frame: CEL len_offset: 0. wid_offset: 0. ! line_list: 20.02 fgs_scan: cont_dwell: C dwell_pnts: 0 dwell_secs: 0.00 scan_width: 3.0000 scan_length: 57.5000 sides_angle: 90.0000 number_lines: 5 scan_rate: 0.0750 first_line_pa: 252.2000 scan_frame: CEL len_offset: 0. wid_offset: 1.0 ! ! end of scan data