! File: 3803C.PROP ! Database: PEPDB ! Date: 19-FEB-1994:20:03:27 coverpage: title_1: PLUTO'S FUV SPECTRUM: CO ABUNDANCE AND FUV title_2: SURVEY sci_cat: SOLAR SYSTEM sci_subcat: MINOR PLANETS proposal_for: GO pi_fname: LAURENCE pi_mi: M pi_lname: TRAFTON pi_inst: TEXAS, UNIVERSITY OF pi_country: USA pi_phone: 512-471-1476 hours_pri: 8.00 num_pri: 2 fos: Y time_crit: Y funds_amount: 83768 funds_length: 12 ! end of coverpage abstract: line_1: We propose FUV observations of Pluto using the FOS/RD with G190H to line_2: survey the spectral region 2200-1800 A for absorption features, and line_3: the FOS/BL with G130H to survey the spectral region 1608-1200 A for line_4: emission features, or fluorescence, in Pluto's atmosphere. The spectral line_5: resolutions are delta lambda = 2.3 A and 1.6 A, respectively. A high line_6: priority will be to search for the cosmogonically important molecule line_7: CO using two vibrational Cameron bands in absorption at 2060 A and line_8: 1989 A, and the (1-0) and other 4th positive vibrational bands in line_9: emission near 1500 A, in order to determine an accurate CO column line_10: abundance and to constrain the rotational temperature of CO. line_11: Detection of both emission and absorption bands would set line_12: constraints on models of atmospheric escape by providing information line_13: on the radial distribution of CO in Pluto's lower atmosphere. We line_14: also search for other species, such as NO. Only HST has the line_15: sensitivity and spatial resolution to obtain Pluto's FUV spectrum. ! ! end of abstract general_form_proposers: lname: TRAFTON fname: LAURENCE title: PI mi: M inst: TEXAS, UNIVERSITY OF country: USA ! lname: STERN fname: S. mi: A. inst: SOUTHWEST RESEARCH INSTITUTE country: USA ! ! end of general_form_proposers block general_form_text: question: 2 section: 1 line_1: Scientific Justification: ! question: 3 section: 1 line_1: Description of proposed observations: line_2: We plan to acquire Pluto when Charon is near line_3: elongation and Pluto is not so far from opposition so that the HST roll angle line_4: angle constraint for BS cannot be met for the Red Side. line_5: For the 2200-1800A region only, a real-time peak up will center line_6: Pluto in the 0.5" aperture and exclude Charon, which will be about 0.9" line_7: away and about 5 times fainter. This aperture will minimize the line_8: contamination of Pluto's spectrum by Charon. A 4 hr exposure will be line_9: obtained with the FOS/RD+G190H+0.5" aperture. An offset to the Blue line_10: Side into the 1" aperture then occurs probably using the same guide line_11: stars. Another Binary Search Onboard Acquisition may be needed for line_12: the blue side. The 1608-1200A region will be observed line_13: with FOS/BL+G130H+1"aperture over an additional 4 hr total exposure. line_14: This will survey the FUV emission spectrum of Pluto and the 4th line_15: positive CO bands near 1500A. No attempt will be made to exclude Charon line_16: from this aperture since the continuum flux from both Pluto and Charon line_17: are both negligible at 1500A owing to the weak solar flux. ! question: 4 section: 1 line_1: Justify the need for the capabilities of HST: line_2: Pluto's FUV spectrum has never been observed. Pluto is the only planet line_3: not visited by a spacecraft. IUE was able to observe Pluto's spectrum line_4: only down to 2500A before reaching its limit of sensitivity. Only HST line_5: has the sensitivity to observe Pluto's FUV spectrum. High spatial line_6: resolution is needed to separate Pluto's spectrum from Charon's. Only line_7: the UV offers molecular absorption coefficients large enough for line_8: detecting many trace constituents. Pluto's strong CH4 spectrum line_9: critically interferes with detecting CO in the infrared; only the UV line_10: allows a practicable way to measure Pluto's CO abundance. CO emission line_11: from Pluto's extended atmosphere can only be observed in the UV. ! question: 5 section: 1 line_1: Justify any special scheduling requests: line_2: The observations need to be scheduled when Charon is not far from line_3: elongation so that its continuum spectrum will not contaminate Pluto's line_4: for the longer wavelength observations using the FOS. Pluto would be line_5: available about 70% of the time. line_6: Schedule to minimize background Dark Count: Avoid the SSA and high line_7: magnetic latitudes. ! question: 6 section: 1 line_1: List any special calibration requirements for your observations line_2: An in-orbit spectrum of a G2V star using G190H FOS/RD and G130H FOS/BL line_3: and also GHRS G160M+LSA would be desirable to better characterize the line_4: grating scattering (red leak) over results of prelaunch tests, line_5: especially near 1500A and 1900A. However, the success of this program is line_6: not dependent on this since the red leak is expected to be comparable to line_7: the dark for G130H and produces a "continuum" which is easily disting- line_8: uished from Pluto's fluorescent emission bands below 1600A. It would, line_10: however, improve the accuracy of the equivalent widths of the CO line_11: absorption bands at 1900-2100A by determining the level of scattered line_12: light at these wavelengths, estimated to be 0.02% of the maximum line_13: visual flux from prelaunch measurements (Blair, Davidsen & Uomoto). line_14: (This would be only a fraction of Pluto's flux at these wavelengths, line_15: but the fraction rises rapidly at smaller wavelengths). ! question: 7 section: 1 line_1: Describe plans for data reduction and analysis. line_2: Initial data reduction will be accomplished by the PI Trafton and Co-I line_3: Stern at the STScI using the STSDAS. The data reduction will include line_4: blemish removal, background subtraction, flat fielding, wavelength line_5: scaling, and conversion to flux units. Special care will be taken to line_6: determine and remove the total background signal from the FOS line_7: observations. The FOS G190H data will be coadded to the sum of our line_8: Cycle 1 GO spectra of Pluto (P2569) to build up the S/N ratio for line_9: detecting the Cameron bands in absorption, and any other species found line_10: in our survey of this spectral region. The facilities at the University line_11: of Texas at Austin and the Southwest Research Institute will be line_12: employed for modeling, analyzing, and interpreting the data. Our line_13: objectives are as follows: line_14: * Obtain calibrated spectra in flux units vs wavelength for Pluto line_15: between 2200 and 1800A at spectral resolution of 1.75A , and in a line_16: 35A interval around 1510A at 19A. line_17: * Survey the spectra for absorption and emission features, line_18: especially the Cameron bands of CO in absorption and the 4th positive line_19: bands of CO in emission. line_20: * Identify any newly discovered species in this first survey. line_21: Analyze their implications for Pluto's aeronomy and cosmogony. line_22: Compare and contrast Pluto's atmosphere with Triton's as determined by line_23: Voyager and our companion HST proposal. ! question: 7 section: 2 line_1: * Measure the equivalent widths of any detected CO or other bands; line_2: obtain column abundances. line_3: * Measure the Full Widths at Half Maximum and general contours of line_4: the CO and other bands. Model the rotational distribution of the line_5: observed vibrational CO bands (cf., for example, Gero et al., 1937) vs line_6: abundance and temperature to constrain the atmospheric temperature. line_7: Use the result with the scale height measured during the June 1988 line_8: stellar occultation to constrain the mean molecular weight of the line_9: atmosphere. Couple this with the derived abundances to check for line_10: completeness in the identification of Pluto's bulk gaseous constitu- line_11: ents. Any discrepancy is probably the signature of N2 in Pluto's line_12: atmosphere. line_13: * Compare the abundances derived from CO absorption and CO line_14: emission to set constraints on the radial distribution of CO in line_15: Pluto's lower atmosphere. Construct atmospheric structural models line_16: with CO scale height as a free parameter to be determined by this line_17: constraint. Compare the result with the 60 km scale height at the line_18: occultation level. Use the result to constrain models of line_19: hydrodynamic atmospheric escape. ! question: 8 section: 1 line_1: Additional comments or requests: line_2: None. ! question: 9 section: 1 line_1: Description of any previous HST data: line_2: a. List HST program numbers and titles, and specify whether they are line_3: related to this project or not. line_4: Trafton: line_5: 1202 Lyman-alpha and H2 Survey; No line_6: 1203 Jovian Auroral Ly-alpha Profile; No line_7: 1204: Io Proton Aurora? No line_8: 1205: SO2 on Io; No line_9: 1206 Sulfur Near Io; No line_10: 2569: UV Rotational Light Curves for Pluto, and Charon's UV Spectrum; line_11: Yes line_12: 2957 High Resolution UV Spectropy of Triton,; No line_13: 2560: Integrated Dynamical and Spectroscopic Observations of Jupiter line_14: and Saturn; No line_15: Stern: line_16: 2957 High Resolution UV Spectropy of Triton,; No line_17: 2569: UV Rotational Light Curves for Pluto, and Charon's UV Spectrum; line_18: Yes line_19: b. Summarize the main results obtained from previous related programs. line_20: No results yet. line_21: c. List publications resulting from the above data (Format: Title, line_22: Authors,Journal, Volume, Page, and Year.) line_23: "First results from the GHRS: Resolved velocity and density structure ! question: 9 section: 2 line_1: in the beta pictoris circumstellar gas", A. Boggess, F. C. Bruhweiler, line_2: C. A. Grady, D. C. Ebbets, Y. Kondo, L. M. Trafton, J. C. Brandt, and line_3: S. R. Heap, Astrophys. J. (Letters), Aug 15 , 1991. ! question: 10 section: 1 line_1: Resources to be supplied by your institution: line_2: Facilities of the UT Computation Center and Advanced Graphics Laboratory line_3: are available to support this project, as well as a Sun 4 Sparcstation. line_4: A pool of astronomy graduate students is also available from which to line_5: draw research assistants. Ground based observations of Io are line_6: periodically made from MacDonald Observatory for related studies. The line_7: Southwest Research Institute will support this project by providing all line_8: required computing facilities for the Co-I and visiting PI. ! !end of general form text general_form_address: lname: TRAFTON fname: LAURENCE mi: M category: PI inst: UNIVERSITY OF TEXAS addr_1: ASTRONOMY DEPARTMENT addr_2: UNIVERSITY OF TEXAS AT AUSTIN city: AUSTIN state: TX zip: 78712 country: USA phone: 512-471-1476 ! ! end of general_form_address records ! No fixed target records found solar_system_targets: targnum: 1 name_1: PLUTO-RD descr_1: PLANET PLUTO lev1_1: STD = PLUTO, ACQ = 0.07 wind_1: WND1 = 15-FEB-93 TO 15-AUG-93, wind_2: SEP OF PLUTO CHARON FROM EARTH wind_3: GT 0.75" WITHIN WND1 comment_1: OBSERVE PLUTO WITH CHARON NOT FAR comment_2: FROM ELONGATION (OUT OF THE WAY). fluxnum_1: 1 fluxval_1: V = 13.9 +/- 0.5 fluxnum_2: 2 fluxval_2: TYPE = G2V fluxnum_3: 3 fluxval_3: F-CONT(2400) = 1.5 +/- 1.0 E-16 fluxnum_4: 4 fluxval_4: F-CONT(2000) = 1.8 +/- 0.5 E-17 ! ! end of solar system targets ! No generic target records found exposure_logsheet: linenum: 1.000 targname: TALED config: FOS/BL opmode: ACQ aperture: 0.3 sp_element: MIRROR num_exp: 1 time_per_exp: 120S fluxnum_1: 1 fluxnum_2: 2 priority: 1 req_1: RT ANALYSIS; req_2: ORIENT 172D +/- 55D /1-3; req_3: SEQ 1-1.3 WITHIN 100M; req_4: CYCLE 2 / 1-3; req_5: GROUP 1-3 WITHIN 36H; comment_1: ORIENT FLIP OK TOO. ! linenum: 1.200 targname: PLUTO-RD config: FOS/BL opmode: ACQ aperture: 4.3 sp_element: MIRROR num_exp: 1 time_per_exp: 480S fluxnum_1: 1 fluxnum_2: 2 priority: 1 req_1: INT ACQ FOR 1.5-3 comment_1: MAKE A PICTURE. comment_2: FOR REAL TIME CENTERING comment_3: FIGURE DURING EARTH OCCULTATION ! linenum: 1.300 targname: TALED config: FOS/BL opmode: ACQ aperture: 0.3 sp_element: MIRROR num_exp: 1 time_per_exp: 120S fluxnum_1: 1 fluxnum_2: 2 priority: 1 req_1: RT ANALYSIS comment_1: LOCATE APERTURE. ! linenum: 1.500 targname: PLUTO-RD config: FOS/BL opmode: ACQ aperture: 4.3 sp_element: MIRROR num_exp: 1 time_per_exp: 120S fluxnum_1: 1 fluxnum_2: 2 priority: 1 comment_1: MAKE A PICTURE. comment_2: TO VERIFY POINTING AFTER GS REACQ ! linenum: 2.000 targname: PLUTO-RD config: FOS/BL opmode: ACCUM aperture: 1.0 sp_element: G190H wavelength: 1950 num_exp: 1 time_per_exp: 231M s_to_n: 12 fluxnum_1: 4 priority: 1 ! linenum: 2.100 targname: TALED config: FOS/BL opmode: ACQ aperture: 0.3 sp_element: MIRROR num_exp: 1 time_per_exp: 120S fluxnum_1: 1 fluxnum_2: 2 priority: 1 req_2: SEQ 2.1-2.3 WITHIN 100M; req_3: RT ANALYSIS; comment_1: ORIENT FLIP OK TOO. ! linenum: 2.200 targname: PLUTO-RD config: FOS/BL opmode: ACQ aperture: 4.3 sp_element: MIRROR num_exp: 1 time_per_exp: 480S fluxnum_1: 1 fluxnum_2: 2 priority: 1 req_1: INT ACQ FOR 3 comment_1: MAKE A PICTURE. comment_2: FOR REAL TIME CENTERING comment_3: FIGURE DURING EARTH OCCULTATION ! linenum: 2.300 targname: TALED config: FOS/BL opmode: ACQ aperture: 0.3 sp_element: MIRROR num_exp: 1 time_per_exp: 120S fluxnum_1: 1 fluxnum_2: 2 priority: 1 req_1: RT ANALYSIS comment_1: LOCATE APERTURE. ! linenum: 3.000 targname: PLUTO-RD config: FOS/BL opmode: ACCUM aperture: 1.0 sp_element: G130H wavelength: 1300 num_exp: 1 time_per_exp: 231M s_to_n: 5 fluxnum_1: 4 priority: 1 comment_1: SHOULD BE MERGED INTO THE comment_2: SAME OBSSET AS LINE 2. ! ! end of exposure logsheet ! No scan data records found