We propose 3 STIS orbits and one WFC3 orbit to obtain spatially resolved 300-1000 nm spectra of the ice giant Uranus, which will be used to determine (1) whether its northern high latitudes have the same methane depletion that has been inferred at high southern latitudes from similar 2002 observations, or whether it has a different depletion indicating seasonal forcing, (2) cloud and haze structure changes since 2002 (5 years before equinox), and (3) the current cloud structure at high northern latitudes that will be accessible during Cycle 20 (5 years after equinox). The complete lack of discrete cloud features pole-ward of 45 S correlates with the inferred local depletion of methane gas and raises questions about methane depletion at high northern latitudes where discrete cloud features have been recently observed. We propose to answer this question firmly by use of spectral differences in methane and hydrogen absorption near 825 nm. This will constrain the methane distribution over the latitude range from 25 S to 70 N, over which the cloud and haze distribution will also be tightly constrained by spectral limb darkening observations. The three STIS orbits will orient the spectral slit along Uranus' polar axis and step from the edge to the center of the disk, taking advantage of the zonal symmetry of Uranus to reduce total observing time by half. The orbit of WFC3 imaging over a broad range of wavelengths provides key information in support of complex corrections needed to produce well calibrated spectra. These results will be relevant to extra-solar science, as Uranus represents a size class that is the most abundant among Kepler extra-solar planet candidates. Re-observe Uranus with STIS, as was done in 2002 (Program 9035); 3 orbits. One orbit of WFC3 imaging. Original description from Program 9035 (updated slightly): During the first orbit, we will use STIS with grating G430L and a 0.1" slit for wavelengths 290-570 nm and 70 second 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 0.15". At wavelengths below 540 nm, Uranus 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 next two orbits, we propose to use STIS with grating G750L and 0.1" slit for wavelengths 524- 1027 nm and 86 second exposure time each. Sampling the 1.85" radius of Uranus at 0.057" sampling from central meridian to evening limb with an additional exposure on each side to account for impecfect centering in the acquisition requires 36 exposures (18 per orbit). We plan to read out only 7" around Uranus to reduce overhead times. For both gratings, we expect about 5, 000 electrons per pixel at the brightest part of Uranus at the brightest wavelength, which typically gives signal-to-noise ratios of 50 per pixel. The gain 1 setting will be used. Wavecals and G750L fringe flats 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 Uranus with flux-centered checkbox of 33 pixels with aperture F28X50LP and 5 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. We tested our target acquisition method with WFPC2 images in 21 different filters. The root-mean-square deviation in east-west centering between our acquisition method and a limb fitting method was 0.03". The deviation was only 0.02" for an average image of many red and near-infrared WFPC2 images which approximates the throughput of the F28X50LP aperture. Thus, we are confindent that centering on Uranus will be more accurate than required. Time-critical observations: In order to take advantage of the almost perfect east-west symmetry of Uranus (to a lesser degree of Neptune), the slit needs to be aligned along the central meridians. This restricts scheduling of the observations within a few days of opposition for Uranus. The STIS wavecals and G750L fringe flats have been specified to occur at the end of the orbits so that they may occur during occultation. All WFC3 exposures have CR-SPLIT=NO to reduce overhead. POS-TARG offsets for quad filter WFC3 exposures have been specified to place target approximately 20 arcseconds closer to center of array relative to "optimal" aperture locations. This places the planet approximately 10 arcseconds towards the center of the array relative to the "QUAD-FIX" fiducial points. This has been done to reduce telescope move magnitudes (between different quads), while still leaving a 512 x 512 pixel area around the target outside of the quad filter vignetted regions. The proposal uses "available" and "pc use only" features to allow suppression of WAVECALS from beginning of orbits (they have been specified at the end of the orbits) and to specify the "NEW ALIGNMENT" flag per PC's instructions. SOLAR SYSTEM 12 false 0.0 0.0 false false false false AVAILABLE SOLAR SYSTEM PLANET URANUS STD=URANUS B-V=0.56 EARTH SOLAR SYSTEM PLANET OFFSET URANUS STD=URANUS TYPE=POS_ANGLE,RAD=1.8252,ANG=344.6,REF=NORTH B-V=0.56 EARTH SOLAR SYSTEM PLANET OFFSET URANUS STD=URANUS TYPE=POS_ANGLE,RAD=1.9346,ANG=344.6,REF=NORTH B-V=0.56 EARTH SOLAR SYSTEM PLANET OFFSET URANUS STD=URANUS TYPE=POS_ANGLE,RAD=0.9104,ANG=344.6,REF=NORTH B-V=0.56 EARTH STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G750L 7751 STIS/CCD Imaging No No F28X50LP WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F467M WFC3/UVIS Imaging No No F547M WFC3/UVIS Imaging No No F658N WFC3/UVIS Imaging No No FQ727N WFC3/UVIS Imaging No No F763M WFC3/UVIS Imaging No No F845M WFC3/UVIS Imaging No No FQ889N WFC3/UVIS Imaging No No FQ937N CELESTIAL MOSAIC 0.1521 LINE false false 13 164.6 LINE 1 false CELESTIAL MOSAIC .0569 LINE false false 18 164.6 LINE 2 false Timing link suitability includes constraints ([02 After 01 by at most 7.0 days]) The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. Slit-orientation must be parallel to the rotation axis of Uranus (PA = 254.60/74.60 in early Oct 2012) to use Uranus' east-west symmetry. See comments for exposures 2, 4, and 7. To fill orbits, those exposures may be slightly modified. (Tic-Visit :proposal-id 12894 :visit-id "01" :proposal-version -1 :trans-version "20120712" :date "13-Aug-2012 10:19:29.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 251056 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12894 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 12894 :visit-id "01" :obset-id "C1" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 12894 :visit-id "01" :obset-id "D1" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 12894 :visit-id "01" :obset-id "E1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12894 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2659 :al-overhead-at-end 0 :internal-dur-at-end 430 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3015 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12894 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2793 :al-overhead-at-end 0 :internal-dur-at-end 704 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3015 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12894 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2793 :al-overhead-at-end 0 :internal-dur-at-end 704 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3015 :pcs-gap 0 ) true 3 0 Exposure time may be adjusted slightly to fill assigned orbit. Exposure time may be adjusted slightly to fill assigned orbit. Intended to run after URANUS-MOSAIC-RED-1 target sequence. Exposure time may be adjusted slightly to fill assigned orbit. Intended to run after URANUS-MOSAIC-RED-2 target sequence. Timing link suitability includes constraints ([02 After 01 by at most 7.0 days]) The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. VISIT should occur within 7 days of STIS orbits so that Uranus phase angle is < 0.4 degrees difference from STIS observations. (Tic-Visit :proposal-id 12894 :visit-id "02" :proposal-version -1 :trans-version "20120604" :date "09-Jul-2012 10:18:10.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 246112 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12894 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12894 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2666 :al-overhead-at-end 0 :internal-dur-at-end 305 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3015 :pcs-gap 0 ) false 1 0