! File: 3617C.PROP ! Database: PEPDB ! Date: 19-FEB-1994:14:02:22 coverpage: title_1: THE ULTRAVIOLET EMISSIONS OF TITAN sci_cat: SOLAR SYSTEM sci_subcat: SATELLITES proposal_for: GO pi_fname: MELISSA pi_mi: A. pi_lname: MCGRATH pi_inst: SPACE TELESCOPE SCIENCE INSTITUTE pi_country: USA pi_phone: 410-338-4545 hours_pri: 6.00 num_pri: 1 fos: Y funds_amount: 53147 funds_length: 12 off_fname: ETHAN off_lname: SCHREIER off_title: ACTING DEP DIRECTOR off_inst: SPACE TELESCOPE SCIENCE INSTITUTE off_addr_1: 3700 SAN MARTIN DRIVE off_city: BALTIMORE off_state: MD off_zip: 21218 off_country: USA off_phone: 410-338-4740 ! end of coverpage abstract: line_1: Observations are proposed using the FOS to accurately measure the line_2: far-ultraviolet (~1200-1800A) spectrum of Titan at ~3A resolution, line_3: which has been observed previously only by the Voyager Ultraviolet line_4: Spectrometer (UVS) at very low spectral resolution (~30A). line_5: Models of the bright emissions from atomic and molecular nitrogen and N+ in line_6: the Voyager data provide poor fits longward of Ly-alpha. In addition, line_7: several unidentified emissions remain which cannot be explained by N2 or its line_8: dissociation products, including a strong feature at ~1336A. line_9: Positive identifications of these emissions will help determine the relative line_10: contributions by magnetospheric particle precipitation, photoelectrons, and line_11: direct solar excitation to the observed UV dayglow, and will allow line_12: comparison with UV observations of the Earth's airglow and aurora. line_13: In addition, solar reflected light longward of Ly-alpha will be line_14: detected and complements the dayglow observations, allowing line_15: detections or upper limits to be placed on the abundance, line_16: distribution and chemistry of minor constituents such as hydrocarbons, line_17: nitriles, and hazes, which are of considerable interest because of the line_18: striking resemblance between Titan's atmosphere and the primitive line_19: atmosphere of the Earth. ! ! end of abstract general_form_proposers: lname: MCGRATH fname: MELISSA title: PI mi: A. inst: SPACE TELESCOPE SCIENCE INSTITUTE country: USA ! lname: STROBEL fname: DARRELL mi: F. inst: JOHNS HOPKINS UNIVERSITY country: USA ! lname: FELDMAN fname: PAUL mi: D. inst: JOHNS HOPKINS UNIVERSITY country: USA ! lname: MOOS fname: WARREN inst: JOHNS HOPKINS UNIVERSITY country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: Two back-to-back integrations using the FOS in ACCUM mode with Titan centered line_2: in the acquisition aperture will be done. One integration will be performed line_3: using G190H and the other using G130H to cover the far UV spectral region from line_4: 1200-2300A for the purpose of accurate measurement of the NI multiplets at line_5: 1243, 1311, and 1493A, and the molecular nitrogen (N2) LBH bands (1250-2000A) line_6: which are brightest in the far UV; detection of the N2 BH bands (fainter than line_7: the LBH bands) may also be possible. In addition, the far UV reflectance line_8: spectrum will be detected. ! question: 4 section: 1 line_1: HST is the only instrument capable of performing this program at the present line_2: time. Molecular nitrogen is notoriously difficult to detect by ground-based line_3: techniques, and neither the N2 LBH bands nor the UV reflectance of Titan is line_4: observable in the far-UV with the IUE satellite due to lack of sensitivity. line_5: This program also requires superior spectral resolution to that of the Voyager line_6: UVS data. ! question: 5 section: 1 line_1: A real-time analysis is required for target acquisition due to lack of a line_2: standard target acquisition method for bright, extended targets with the FOS. line_3: The current acquisition strategy has been used successfully on numerous line_4: occasions for Io. ! question: 7 section: 1 line_1: We have two Sun Sparcstation IPCs dedicated to the reduction and analysis of line_2: HST data. Extensive software libraries, including the standard HST data line_3: reduction software SDAS as well as IRAF, IDL, etc., are already in place on line_4: these systems. We have previous experience (Shemansky and Strobel 1982; Strobel line_5: et al 1991) modeling the Titan emissions, and detailed models already exist line_6: which can be used to analyse the HST data. In addition, we also have experience line_7: analysing and modeling the N2 LBH bands in the Earth's aurora and airglow line_8: (Feldman and Gentieu 1982; Bowers et al 1987; Morrison et al 1990; Meier et al line_9: 1980) which will be compared with the Titan results. Finally, we have at hand a line_10: program to produce synthetic LBH band spectra for different physical conditions line_11: which can be used for this analysis. ! question: 9 section: 1 line_1: Programs executed: line_3: 3064 HST Observations of Comet Levy (1990c), Weaver (PI), Feldman line_4: Unrelated to present proposal. line_6: Programs accepted for Cycle 1: line_8: 2625 Excitation processes for the Outer Planet UV Emission, Moos (PI), line_9: McGrath, Feldman, Strobel, Shemansky, Clarke. Unrelated to present proposal. line_11: 2627 Io's Atmosphere and it's Interaction with the Plasma Torus, Moos (PI), line_12: McGrath, Feldman, Strobel. Unrelated to the present proposal. line_14: 2442 Cometary Parent Molecules, Feldman (PI). Unrelated to present proposal. line_16: 2481 HST Observations of Periodic Comets, Weaver (PI), Feldman. Unrelated. line_18: 2483 The volatile Composition of New Comets, Weaver (PI), Feldman. Unrelated. ! question: 9 section: 2 line_1: Summary of the main results obtained from previous related programs: line_3: At the time of writing of this proposal, program 3064 was the only one of the line_4: above programs which has been executed, and is unrelated to the present line_5: proposal. line_7: Listing of publications resulting from the above data: line_9: Inner Coma Imaging of Comet Levy (1990c) with the Hubble Space Telescope, line_10: Weaver, A'Hearn, Feldman, Arpigny, Baum, Brandt, Light, Westphal, submitted to line_11: Icarus, August 1991. ! question: 10 section: 1 line_1: The data analysis capabilities outlined above including computer hardware, line_2: software, maintenance, and management, will be made available, as well as line_3: partial salary support for all Co-I's and a student who will participate in the line_4: project. ! !end of general form text general_form_address: lname: MCGRATH fname: MELISSA mi: A. category: PI inst: SPACE TELESCOPE SCIENCE INSTITUTE addr_1: 3700 SAN MARTIN DRIVE city: BALTIMORE state: MD zip: 21218 country: USA phone: 410-338-4545 ! ! end of general_form_address records ! No fixed target records found solar_system_targets: targnum: 1 name_1: TITAN-ACQ descr_1: SATELLITE TITAN lev1_1: STD=SATURN lev2_1: STD=TITAN wind_1: SEP OF TITAN SATURN FROM EARTH GT 100" wind_2: OLG OF SATURN BETWEEN 330 30 comment_1: TITAN ACQ NEAR ELONGATION (LINES comment_2: 1-2) WHEN OLG TITAN BETWEEN ABOUT comment_3: 250 270 OR 70 90 FOLLOWED BY SCIENCE comment_4: OBSERVATIONS (LINES 3-4); INTENT comment_5: IS THAT ENTIRE SET OF OBSERVATIONS comment_6: BE DONE NEAR SATURN OPPOSITION WITH comment_7: TITAN NEAR ELONGATION WITH comment_8: MAXIMUM POSSIBLE SEPARATION (GT 100") comment_9: BETWEEN SATURN AND TITAN TO REDUCE comment_10: SCATTERED LIGHT IN FOS fluxnum_1: 1 fluxval_1: SURF(V)=9.5 ! targnum: 2 name_1: TITAN descr_1: SATELLITE TITAN lev1_1: STD=SATURN lev2_1: STD=TITAN wind_1: SEP OF TITAN SATURN FROM EARTH GT 100" wind_2: OLG OF SATURN BETWEEN 330 30 comment_1: SCIENCE OBSERVATIONS OF TITAN comment_2: NEAR TITAN ELONGATION AND comment_3: SATURN OPPOSITION (TO REDUCE comment_4: EARTH AIRGLOW CONTAMINATION) fluxnum_1: 1 fluxval_1: SURF(V)=9.5 ! ! end of solar system targets ! No generic target records found exposure_logsheet: linenum: 1.000 targname: TITAN config: FOS/BL opmode: IMAGE aperture: 4.3 sp_element: G270H num_exp: 1 time_per_exp: 600S fluxnum_1: 1 priority: 1 param_1: SUB-STEP=4, param_2: Y-SIZE=5, param_3: Y-SPACE=128, param_4: COMB=YES req_1: CYCLE 2 / 1-4; req_2: RT ANALYSIS FOR 2; req_3: GROUP 1-4 NO GAP; req_4: SEQ 1-2 NO GAP comment_1: TITAN ACQUISITION SPECTRAL IMAGE ! linenum: 2.000 targname: TITAN config: FOS/BL opmode: IMAGE aperture: 4.3 sp_element: G270H num_exp: 1 time_per_exp: 20S fluxnum_1: 1 priority: 1 param_1: STEP-TIME=1.0, param_2: SUB-STEP=1, param_3: Y-SIZE=4, param_4: Y-SPACE=64, param_5: COMB=NO comment_1: QUICK MAP OF 4.3 APERTURE AFTER UPLINK comment_2: AND POINTING CORRECTION TO DETERMINE comment_3: TRUE LOCATION OF TITAN IN APERTURE ! linenum: 3.000 targname: TITAN config: FOS/BL opmode: ACCUM aperture: 4.3 sp_element: G190H num_exp: 1 time_per_exp: 72M fluxnum_1: 1 priority: 1 param_1: STEP-PATT=SINGLE ! linenum: 4.000 targname: TITAN config: FOS/BL opmode: ACCUM aperture: 4.3 sp_element: G130H num_exp: 1 time_per_exp: 158M fluxnum_1: 1 priority: 1 param_1: STEP-PATT=SINGLE ! ! end of exposure logsheet ! No scan data records found