9330( 8) - 06/27/03 11:21 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9330 Version: 8 Check-in Date: 27-Jun-2003 11:20:45 1.Proposal Title: Spatially Resolved Spectroscopy of Uranus and Neptune ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Erich Karkoschka University of Arizona CoI: Dr. Mark Lemmon Texas A&M University N CoI: Dr. Martin Tomasko University of Arizona N ------------------------------------------------------------------------------------ 5. Abstract We propose to use STIS to obtain data cubes for Uranus (Cycle 10) and Neptune (Cycle 11). The spectrum between 290 and 1020 nm is sampled at 2000 wavelengths. The north- south position on the planetary disk is sampled along the slit every 0.05". The east-west position is sampled by successive exposures every 0.05" (longward of 520 nm wavelength) and 0.10-0.15" (shortward of 520 nm). Such data have never been obtained. Only HST, with STIS, has the capability to record spatial variations of narrow methane and hydrogen absorption and Raman scattering features. We have obtained such data for Saturn by ground-based observations which permitted a comprehensive understanding of the vertical haze and cloud structure as a function of latitude. Similar improvements are expected from the proposed data for Uranus and Neptune. HST has revealed exciting images of Uranus and Neptune while their quantitative analysis has been slow due to limitations in available filters. Our short, spatially-resolved spectroscopic program will reveal accurate spectral shapes across each WFPC2 filter which then will greatly improve the reliability of interpretations based on hundreds of past and future WFPC2 images. Similarly, WFPC2 images of Titan required the addition of STIS spectra before the latest improvements in our understanding of its atmosphere were possible. ------------------------------------------------------------------------------------ 9330( 8) - 06/27/03 11:21 - [ 2] Observations Description ------------------------ Cycle 11: During the last orbit, we will use STIS with grating G430L and a 0.1" slit for wavelengths 290-570 nm and 2.8 min exposure time each. The slit orientation with be parallel to the central meridian. Considering overhead times, 13 positions will be possible distributed between the central meridian and the evening limb equally spaced by 0.10". At wavelengths below 540 nm, Neptune does not display much latitudinal contrasts. Thus, the significant center-to- limb variations are expected to be well recorded by those slit positions. For the first three orbits, we propose to use STIS with grating G750L and 0.1" slit for wavelengths 524- 1027 nm and 3.4 min exposure time each. Sampling the 1.2" radius of Neptune at 0.05" sampling from central meridian to evening limb with an additional exposure to account for impecfect centering in the acquisition requires 26 exposures (6 during the first orbit after acquisition and 10 each during the following orbits plus two additional ones for overlap between different orbits). We plan to read out only 7" around Neptune to reduce overhead times. For both gratings, we expect about 4, 000 electrons per pixel at the brightest part of Neptune at the brightest wavelength, which typically gives signal-to-noise ratios of 50 per pixel. The gain 1 setting will be used. Spacecraft time: Giude star acquisition (6 min), three re-acquisitions (15 min), target acquisition (19 min), exposure time (13 x 2.8 min + 28 x 3.4 min = 132 min), exposure overheads (4 x 5 min = 20 min), small angle offsets (37 x 0.33 min = 12 min), totaling 204 min or 51 min per orbit, which is the maximum time per orbit at opposition. Both gratings will require wavelength calibration exposures (wavecal) which will be scheduled during the occultation periods between orbits. The G750L grating will require flatfields (fringe flat) which also will be scheduled between orbits. Overhead for data management will not be required since we will read out only 140 rows. The target acquisition will be a diffuse acquisition on Neptune with flux- centered checkbox of 39 pixels with aperture F28X50LP and 14 sec exposure time. The target acquisition exposure will help in the navigation of the exposures with the G750L grating. The overlapping spectral region will facilitate navigation of the remaining exposures. Cycle 10: We will use the same observing technique as in Cycle 11, but this time for Uranus instead of Neptune. Uranus allows exposure times three times shorter as for Neptune to reach similar exposure levels. This allows to compress the orbit with G430L into the partial orbit after the aquisition and to compress the three orbits with G750L into two. Real Time Justification ----------------------- Time-critical observations: In order to take advantage of the almost perfect east-west symmetry of Uranus and Neptune, the slit needs to be aligned along the central meridian. This restricts scheduling of the observations within a few days of opposition. Neptune observations should be taken about one year after the Uranus observations in order to have time to learn from the Uranus observation and possibly adjust the Neptune observations if necessary. Calibration Justification ------------------------- 9330( 8) - 06/27/03 11:21 - [ 3] Additional Comments ------------------- ------------------------------------------------------------------------------------ 9330( 8) - 06/27/03 11:21 - [ 4] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: NEPTUNE-CENTER-OF-LIGHT ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: OFFSET NEPTUNE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=NEPTUNE | TYPE=POS_ANGLE,RAD=0.1,ANG=167.7,REF=NOR | TH | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 7.9 | Neptune central meridian, 0.1" B-V = 0.39 | towards south pole U-B = 0.17 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: NEPTUNE-MOSAIC-BLUE ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: OFFSET NEPTUNE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=NEPTUNE | TYPE=POS_ANGLE,RAD=1.2168,ANG=257.7,REF= | NORTH | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 7.9 | Neptune mosaic from evening limb to B-V = 0.39 | center U-B = 0.17 | | ------------------------------------------------------------------------------------------------------------------------------------ 9330( 8) - 06/27/03 11:21 - [ 5] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: NEPTUNE-MOSAIC-RED-1 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: OFFSET NEPTUNE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=NEPTUNE | TYPE=POS_ANGLE,RAD=1.2168,ANG=257.7,REF= | NORTH | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 7.9 | Neptune mosaic from evening limb to B-V = 0.39 | afternoon side U-B = 0.17 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 4 | TARGET NAME: NEPTUNE-MOSAIC-RED-2 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: OFFSET NEPTUNE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=NEPTUNE | TYPE=POS_ANGLE,RAD=0.9633,ANG=257.7,REF= | NORTH | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 7.9 | Neptune mosaic on afternoon side B-V = 0.39 | towards center U-B = 0.17 | | ------------------------------------------------------------------------------------------------------------------------------------ 9330( 8) - 06/27/03 11:21 - [ 6] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 5 | TARGET NAME: NEPTUNE-MOSAIC-RED-3 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: OFFSET NEPTUNE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=NEPTUNE | TYPE=POS_ANGLE,RAD=0.4563,ANG=257.7,REF= | NORTH | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 7.9 | Neptune mosaic from afternoon side B-V = 0.39 | to center U-B = 0.17 | | ------------------------------------------------------------------------------------------------------------------------------------ 9330( 8) - 06/27/03 11:21 - [ 7] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type LINE Pattern_Purpose MOSAIC Number_Of_Points 13 Point_Spacing 0.1014 Coordinate_Frame CELESTIAL Pattern_Orient 77.7 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type LINE Pattern_Purpose MOSAIC Number_Of_Points 6 Point_Spacing 0.0507 Coordinate_Frame CELESTIAL Pattern_Orient 77.7 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 Primary_Pattern Secondary_Pattern Pattern_Type LINE Pattern_Purpose MOSAIC Number_Of_Points 11 Point_Spacing 0.0507 Coordinate_Frame CELESTIAL Pattern_Orient 77.7 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 9330( 8) - 06/27/03 11:21 - [ 8] Visit: 01 Visit Priority: Visit Requirements: SCHED 100% AFTER 19-MAY-2003 ORIENT 32.6D TO 32.8D ORIENT 212.6D TO 212.8D On Hold Comments: Additional Comments: Slit-orientation must be parallel to the rotation axis of Neptune (PA = 347.7 deg in August 2003) to use Neptune's east-west symmetry. The AFTER requirement is based on the current scheduling for the Uranus observations (GO 9035) for 19-AUG-2002, allowing at least nine months after that date to analyze the data. Exposure times of exposures 12, 22, 32, and 42 may be slightly adjusted in case of longer or shorter than expected visibility periods. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NEPTUNE-CEN STIS/C ACCUM F28X50L MIRROR GAIN=4 ,SIZEAXIS2=140 , 1 14 S TER-OF-LIGH CD P CR-SPLIT=NO T ------------------------------------------------------------------------------------------------------------------------------------ 2 NEPTUNE-CEN STIS/C ACQ 50CCD MIRROR ACQTYPE=DIFFUSE , 1 8 S TER-OF-LIGH CD DIFFUSE-CENTER=FLUX-CENTROID , T CHECKBOX=33 ------------------------------------------------------------------------------------------------------------------------------------ 12 NEPTUNE-MOS STIS/C ACCUM 52X0.1 G750L 7751 SIZEAXIS2=140 ,CR-SPLIT=NO 1 195 S PATTERN 2 NO SPLIT MAX AIC-RED-1 CD DUR 360S ------------------------------------------------------------------------------------------------------------------------------------ 13 WAVE STIS/C ACCUM 52X0.1 G750L 7751 1 DEF CD Comments: Added since there is no automatic wavecal ------------------------------------------------------------------------------------------------------------------------------------ 14 CCDFLAT STIS/C ACCUM 52X0.1 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 21 CCDFLAT STIS/C ACCUM 52X0.1 G750L 7751 2 DEF CD Comments: Preferably scheduled close to exposure 22 ------------------------------------------------------------------------------------------------------------------------------------ 22 NEPTUNE-MOS STIS/C ACCUM 52X0.1 G750L 7751 SIZEAXIS2=140 ,CR-SPLIT=NO 1 195 S PATTERN 3 NO SPLIT MAX AIC-RED-2 CD DUR 360S ------------------------------------------------------------------------------------------------------------------------------------ 24 CCDFLAT STIS/C ACCUM 52X0.1 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 31 CCDFLAT STIS/C ACCUM 52X0.1 G750L 7751 2 DEF CD Comments: Preferably scheduled close to exposure 32 ------------------------------------------------------------------------------------------------------------------------------------ 32 NEPTUNE-MOS STIS/C ACCUM 52X0.1 G750L 7751 SIZEAXIS2=140 ,CR-SPLIT=NO 1 195 S PATTERN 3 NO SPLIT MAX AIC-RED-3 CD DUR 360S ------------------------------------------------------------------------------------------------------------------------------------ 9330( 8) - 06/27/03 11:21 - [ 9] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 34 CCDFLAT STIS/C ACCUM 52X0.1 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 42 NEPTUNE-MOS STIS/C ACCUM 52X0.1 G430L 4300 SIZEAXIS2=140 ,CR-SPLIT=NO 1 160 S PATTERN 1 NO SPLIT MAX AIC-BLUE CD DUR 300S ------------------------------------------------------------------------------------------------------------------------------------ 9330( 8) - 06/27/03 11:21 - [ 10] Summary Form for Proposal 9330 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 50CCD 52X0.1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters GAIN=4 SIZEAXIS2=140 CR-SPLIT=NO CHECKBOX=33 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 100% AFTER 19-MAY-2003 ORIENT 32.6D TO 32.8D ORIENT 212.6D TO 212.8D PATTERN 2 NO SPLIT MAX DUR 360S PATTERN 3 NO SPLIT MAX DUR 360S PATTERN 1 NO SPLIT MAX DUR 300S ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G750L G430L ------------------------------------------------------------------------------------------------------------------------------------ Target Names NEPTUNE-CENTER-OF-LIGHT NEPTUNE-MOSAIC-RED-1 WAVE CCDFLAT NEPTUNE-MOSAIC-RED-2 NEPTUNE-MOSAIC-RED-3 NEPTUNE-MOSAIC-BLUE ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 7751 4300 ------------------------------------------------------------------------------------------------------------------------------------