Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 1082c Report Date: 09-May-96:16:07 Version: ********** Check-in Date: ********** 1.Proposal Title: HELIUM ABUNDANCE IN JOVIAN PLANET UPPER ATMOSPHERES ------------------------------------------------------------------------------------ 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 large masses of the Jovian planets make it likely that they have retained their primordial abundance of material accreted from the solar nebula. The helium abundance in the upper atmospheres of these planets reflects the primordial abundance and the structural evolution of the planet. We propose to determine the Helium fraction in the upper atmosphere of each Jovian planet by measuring the ratio of the refractivities of its atmosphere for two wavelengths during stellar occultations. Revision History: Updated for Cycle 2 submission--ASB 3/20/92; ------------------------------------------------------------------------------------ 8. Scientific Key Words: JOVIAN PLANETS, OCCULTATIONS, UPPER ATMOSPHERES, HELIUM ABUNDANCES ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 6.00 par: 0 10. Num targs pri: 16 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HSP ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 1082c PI: Robert C. Bless Proposal Title: HELIUM ABUNDANCE IN JOVIAN PLANET UPPER ATMOSPHERES ------------------------------------------------------------------------------------ 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 the ephemerides of the Jovian planets to identify those occultations of sufficient signal-to-noise ratio to achieve the goals outlined in Section 2. The observation sequence is as follows: 1) Obtain a WFPC image to determine the exact occultation parameters. 2) Acquire occultation candidate using onboard acquisition mode. 3) Scan along the track that the star will follow relative to the planet in order to determine the planetary contribution to the background. 4) Start continous series of 10ms integrations 10 arcseconds prior to the predicted immersion time (for Jupiter). The occultation observation will require simple tracking on the star before atmosphere immersion, complex tracking on the stellar image as it moves along the planetary limb, and simple tracking after atmosphere emersion. This sequence of integrations must be continuous. 6) Scan along the track that the star will follow relative to the planet 7) Monitor dark current on ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. We can achieve a much better signal-to-noise ratio for determining the helium abundance from these occultations than would be possible from the ground for the following reasons: (i) the lower level of background scattered light seen by the ST; (ii) our ability to reject background light by employing small focal plane apertures; (iii) the absence of scintillation noise, which has strong components at frequencies comparable to the occultation timescale; and (iv) the much greater span of wavelengths that can be covered--well into the UV for occultations of stars of early spectral type. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. Aquisition of the object near the planet may be difficult. Tracking the occulted star in some cases will require a real time update, due to its complicated path caused by refraction in the occulting planet's atmosphere and the uncertainties in predicting the ST orbit. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. A prior scan of the path the star will take through the planetary atmosphere is needed to map the scattered light field (necessary for the data reduction). Once the star is in the beamsplitter aperture and is being occulted by the planet, the integration sequence must be uninterrupted as the data are time-critical. ------------------------------------------------------------------------------------ 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. 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. The helium abundances in the upper atmospheres of the Jovian Planets can be obtained with the HSP by measuring the refractivities of the atmospheres at two different wavelengths during stellar occultations. The helium abundance reflects the primordial abundance and the structural evolution of the planet. ------------------------------------------------------------------------------------ 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: 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 = 1082c [ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 12 GSC5808- STAR TO BE OCCULTED BY PLATE-ID = 00CT, J2000 BKG 1 V = 13.1 +/- 0.3 00138 SATURN. RA = 22H 06M 26.87S +/- 2 B = 13.6 +/- 0.3 CLOSE APPROACH AT 29- 0.5", 3 R = 12.4 +/- 0.3 APR-93:20:56 DEC = -12D 55' 49.1" +/- 0.5", Comments: STAR POSITION WILL BE UPDATED BEFORE OBSERVATION IS PERFORMED. CONTACT: AMANDA S. BOSH, MIT SOLAR ELONG 71D ------------------------------------------------------------------------------------------------------------------------------------ 13 00138-OFFSET OFFSET TARGET FOR PLATE-ID = 00CT, J2000 1 B = 15.2 +/- 0.6 GSC5808- GSC5808-00138 RA = 22H 06M 23.96S +/- 00943 0.5", DEC = -12D 56' 11.3" +/- 0.5", Comments: STAR POSITION WILL BE UPDATED BEFORE OBSERVATION IS PERFORMED. CONTACT: AMANDA S. BOSH, MIT ------------------------------------------------------------------------------------------------------------------------------------ TARGET LIST b)Solar System Targets ID = 1082c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 19 | TARGET NAME: 00138-BACKGROUND ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: OFFSET SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = SATURN | TYPE = POS_ANGLE, | RAD = 24.4, | ANG = 68.2, | 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 = 1082c [ 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 ONBRD- VIS ACQ ------------------------------------------------------------------------------------------------------------------------------------ 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 OCC VIS ------------------------------------------------------------------------------------------------------------------------------------ 20.01 USE 00138- SAMPLE- X467 SEQ 20.01 - 20.03 BACK- BACKGROUND TIME=0.05 CYCLE 2/20.01 - SCAN PRECISION=HIGH 20.10 DATA-FORMAT=ALL PMT-ANALOG=1000 VIS-ANALOG=100 ------------------------------------------------------------------------------------------------------------------------------------ 20.02 USE 00138- SAMPLE-TIME=0.1 X467 BACK- BACKGROUND PRECISION=HIGH SCAN DATA-FORMAT=ALL PMT-ANALOG=1000 VIS-ANALOG=100 ------------------------------------------------------------------------------------------------------------------------------------ 20.03 USE 00138- SAMPLE- X467 BACK- BACKGROUND TIME=0.05 SCAN PRECISION=HIGH DATA-FORMAT=ALL PMT-ANALOG=1000 VIS-ANALOG=100 ------------------------------------------------------------------------------------------------------------------------------------ 20.04 USE 00138- X100 ONBOARD ACQ FOR ONBRD- OFFSET 20.10 ACQ SEQ 20.04 - 20.10 NO GAP GROUP 20.01 - 20.04 WITHIN 9H ------------------------------------------------------------------------------------------------------------------------------------ 20.1 USE GSC5808- SAMPLE-TIME=0.1 X100 AT 29-APR-93:19:41 RING- 00138 PRECISION=HIGH +/- 6M OCC DATA-FORMAT=ALL PMT-ANALOG=1000 VIS-ANALOG=100 Comments: END EXPOSURE AT 29-APR- 93:22:25.; +/- 1M TO AVOID ABSOLUTE COMMANDING ; ORIGINAL +/- 1M SHOULD BE RESPECTED ; IN SCHEDULING. ------------------------------------------------------------------------------------------------------------------------------------ Scan Paramters Form Proposal ID: 1082c [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 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): 57.5000 Angle between sides (degrees) 90.00 Number of lines: 1 Scan rate (arc-sec/sec): 0.0750 PA of first scan line (degrees) 252.200 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): 57.5000 Angle between sides (degrees) 90.00 Number of lines: 5 Scan rate (arc-sec/sec): 0.0750 PA of first scan line (degrees) 252.200 Scan frame (CEL or S/C): CEL Length Offset (arc-sec): 0. Width Offset (arc-sec): 1.0000 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 1082c [ 8] 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 6.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SPATIAL SCAN; CRIT OBS; SEQ 20.01 - 20.03; CYCLE 2/20.01 - 20.10; ONBOARD ACQ FOR 20.10; SEQ 20.04 - 20.10 NO GAP; GROUP 20.01 - 20.04 WITHIN 9H; AT 29-APR-93 19 41 +/- 6M; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F750W/F320N ------------------------------------------------------------------------------------------------------------------------------------ Target Names GSC5808-00138 00138-OFFSET GSC5808-00943 00138-BACKGROUND ------------------------------------------------------------------------------------------------------------------------------------