12900( 3) - 04-Feb-2013 13:19:16 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12900 Version: 3 Check-in Time: 04-Feb-2013 13:19:16 STScI Edit Number: 1 Title Mapping the Methane and Aerosol Distributions within Titan's Troposphere: Complementing The Cassini/VIMS T90 Flyby of Titan ------------------------------------------------------------------------------------ Type Cycle GO 20 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Eliot Young Southwest Research Institute Y CoI: Dr. Carrie M Anderson NASA Goddard Space Flight Center Y CoI: Prof. Jason W. Barnes University of Idaho Y ------------------------------------------------------------------------------------ Abstract Titan's atmosphere is mainly nitrogen gas with several trace constituents, including methane at the few percent level. The presence of methane has been a puzzle for decades, since the CH4 in Titan's atmosphere is expected to be destroyed by UV photolysis in ten million years or so. The source of Titan's atmospheric methane continues to be a major question. We propose a set of three STIS image cubes with the G750M grating at 0.62, 0.72 and 0.89 |*|m methane bands. These bands probe altitudes from the surface to 70 km; unlike CH4 bands at 1.6 or 2.3 |*|m, these cubes will provide a 3-D picture of Titan's troposphere (below 40 km). The Cassini/VIMS visible channel has not been useful for this purpose for two reasons: its spectral resolution (about R=100) is coarse and its inconsistent background subtraction scheme that can lead to "stripes." HST/STIS resolves Titan's 1" disk into over 80 spatially resolved spectra, each with a spectral resolution greater than R=5000. STIS is a unique tool for mapping the 3-D distributions of CH4 and aerosols in Titan's troposphere. We request observations within a day of the Cassini flyby of Titan on April 5, 2013 around 21:40 UT in order to combine Cassini/VIMS and STIS mage cubes. Together, the visible (STIS) and IR (VIMS) image cubes will probe altitudes from the surface to the stratosphere (several hundred km). The proposed STIS image cubes will provide the best tropospheric map of CH4 to date, relevant to surface/atmospheric coupling of CH4, latitudinal inhomogeneity of CH4 or aerosols, or the presence of condensates at low altitudes. ------------------------------------------------------------------------------------ Observations Description ------------------------ This proposal consists of three orbits to observe Titan with the G750M grating, each identical except for the wavelength setting. The schedule for each orbit consists of an initial acquisition followed by 20 spectra using the 52x0.05 arcsec slit, which we will step across Titan in 0.05 arcsec increments to produce image cubes. The three wavelength settings are centered at 6252, 7283 and 8825 Angstroms, respectively. Real Time Justification ----------------------- This proposal needs to be concident with Cassini/VIMS spacecraft observations, 12900( 3) - 04-Feb-2013 13:19:16 - [ 2] specifically, the Cassini T90 flyby of Titan. The window for these three orbits is between 1:00 to 6:00 UT on April 6, 2013. Calibration Justification ------------------------- We are concerned about wavelength-dependent scattered light in the 8825 spectra. This was a huge issue for us in previous G750L spectra, and although the PSF is slightly smaller in the G750M spectra, we still think it will be a problem. In GO-8580 we had WFPC2 images of Titan at selected wavelengths that we could use to correct the red "anti-leak", but we do not have time to make similar calibration observations in this program. Additional Comments ------------------- ------------------------------------------------------------------------------------ 12900( 3) - 04-Feb-2013 13:19:16 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: TITAN ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE Titan ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=SATURN STD=TITAN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS SEP OF TITAN SATURN FROM EARTH GT 45", SEP OF TITAN RHEA FROM EARTH GT 10" ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 7.5 +/- 1.0 Ephemeris Center: EARTH ------------------------------------------------------------------------------------------------------------------------------------ 12900( 3) - 04-Feb-2013 13:19:16 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type STIS-PERP-TO-SLIT Pattern_Purpose MOSAIC Number_Of_Points 20 Point_Spacing 0.05 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 0.0 Angle_Between_Sides Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ 12900( 3) - 04-Feb-2013 13:19:16 - [ 5] Visit: 01 Visit Requirements: BETWEEN 05-APR-2013:21:45:00 AND 06-APR-2013:06:00:00 On Hold Comments: Additional Comments: First image cube of Titan, consisting of 20 spectra obtained by stepping the 52x0.05 slit across Titan at 0.05 increments. This FIRST orbit includes the initial acquisition of Titan, and thus allocates less time to the spectra. The second and third orbits (at longer wavelengths) will avoid the main acquisition overhead. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 TITAN STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=19, 1 0.1 S DIFFUSE-CENTER=GEOMETRIC-CENTE R ------------------------------------------------------------------------------------------------------------------------------------ 2 TITAN STIS/CCD ACCUM 52X0.05E1 G750M 6252 SIZEAXIS2=248, CR-SPLIT=NO, 1 49 S PATTERN 1 2 WAVECAL=NO ------------------------------------------------------------------------------------------------------------------------------------ 3 WAVE STIS/CCD ACCUM 52X0.05 G750M 6252 1 DEF NEW ALIGNMENT ------------------------------------------------------------------------------------------------------------------------------------ 4 TITAN STIS/CCD ACCUM 52X0.05E1 G750M 7283 SIZEAXIS2=248, CR-SPLIT=NO, 1 76 S PATTERN 1 4 WAVECAL=NO ------------------------------------------------------------------------------------------------------------------------------------ 5 WAVE STIS/CCD ACCUM 52X0.05 G750M 7283 1 DEF NEW ALIGNMENT ------------------------------------------------------------------------------------------------------------------------------------ 6 CCDFLAT STIS/CCD ACCUM 52X0.05 G750M 7283 2 DEF ------------------------------------------------------------------------------------------------------------------------------------ 7 CCDFLAT STIS/CCD ACCUM 52X0.05 G750M 7283 2 DEF ------------------------------------------------------------------------------------------------------------------------------------ 8 TITAN STIS/CCD ACCUM 52X0.05E1 G750M 8825 SIZEAXIS2=248, CR-SPLIT=NO, 1 76 S PATTERN 1 8 WAVECAL=NO ------------------------------------------------------------------------------------------------------------------------------------ 9 WAVE STIS/CCD ACCUM 52X0.05 G750M 8825 1 DEF NEW ALIGNMENT ------------------------------------------------------------------------------------------------------------------------------------ 10 CCDFLAT STIS/CCD ACCUM 52X0.05 G750M 8825 2 DEF ------------------------------------------------------------------------------------------------------------------------------------ 11 CCDFLAT STIS/CCD ACCUM 52X0.05 G750M 8825 2 DEF ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ TITAN 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 1 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 2 none none none 1 N/A 1 12900( 3) - 04-Feb-2013 13:19:16 - [ 6] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 3 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 4 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 5 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 6 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 7 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 8 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 9 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 10 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 11 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 12 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 13 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 14 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 15 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 16 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 17 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 18 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 19 none none none 1 N/A 1 TITAN 2 STIS/CCD ACCUM 52X0.05E G750M 6252 20 none none none 1 N/A 1 WAVE 3 STIS/CCD ACCUM 52X0.05 G750M 6252 none none none none 1 N/A TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 1 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 2 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 3 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 4 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 5 none none none 2 N/A 1 12900( 3) - 04-Feb-2013 13:19:16 - [ 7] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 6 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 7 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 8 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 9 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 10 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 11 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 12 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 13 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 14 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 15 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 16 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 17 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 18 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 19 none none none 2 N/A 1 TITAN 4 STIS/CCD ACCUM 52X0.05E G750M 7283 20 none none none 2 N/A 1 WAVE 5 STIS/CCD ACCUM 52X0.05 G750M 7283 none none none none 2 N/A CCDFLAT 6 STIS/CCD ACCUM 52X0.05 G750M 7283 none none 1 none 2 N/A CCDFLAT 6 STIS/CCD ACCUM 52X0.05 G750M 7283 none none 2 none 2 N/A CCDFLAT 7 STIS/CCD ACCUM 52X0.05 G750M 7283 none none 1 none 2 N/A CCDFLAT 7 STIS/CCD ACCUM 52X0.05 G750M 7283 none none 2 none 2 N/A TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 1 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 2 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 3 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 4 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 5 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 6 none none none 3 N/A 1 12900( 3) - 04-Feb-2013 13:19:16 - [ 8] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 7 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 8 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 9 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 10 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 11 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 12 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 13 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 14 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 15 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 16 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 17 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 18 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 19 none none none 3 N/A 1 TITAN 8 STIS/CCD ACCUM 52X0.05E G750M 8825 20 none none none 3 N/A 1 WAVE 9 STIS/CCD ACCUM 52X0.05 G750M 8825 none none none none 3 N/A CCDFLAT 10 STIS/CCD ACCUM 52X0.05 G750M 8825 none none 1 none 3 N/A CCDFLAT 10 STIS/CCD ACCUM 52X0.05 G750M 8825 none none 2 none 3 N/A CCDFLAT 11 STIS/CCD ACCUM 52X0.05 G750M 8825 none none 1 none 3 N/A CCDFLAT 11 STIS/CCD ACCUM 52X0.05 G750M 8825 none none 2 none 3 N/A 12900( 3) - 04-Feb-2013 13:19:16 - [ 9] Summary Form for Proposal 12900 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.05, 52X0.05E1, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=DIFFUSE, CHECKBOX=19, CR-SPLIT=NO, DIFFUSE-CENTER=GEOMETRIC-CENTER, SIZEAXIS2=248, WAVECAL=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 05-APR-2013:21:45:00 AND 06-APR-2013:06:00:00, NEW ALIGNMENT, PATTERN 1 2, PATTERN 1 4, PATTERN 1 8 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G750M, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names CCDFLAT, TITAN, WAVE ------------------------------------------------------------------------------------------------------------------------------------