This is a resubmission of proposal 336. Please ignore submission of #336 from yesterday. -1522343731 Assigned ID: 954 ----- Attempting Submission 1 (Fri Apr 08 22:59:53 GMT 2016) ----- A visit planner does not need to be run. The visits are identical to GO 8580. 0 Phase II ID is a required field. Observing Description is a required field. This target is not used in this proposal. Keyword is a required field. Description is a required field. Level 1 Type is a required field. 0 Numer of exposures was decreased from 16 to 15 and exposure time each from 86 to 83 sec in order to fit decreased visibility duration. The lost exposure on Titan's limb is not important. WAVECAL exposure at the end of the orbit was approved by the STIS group for GO 14612 and GO 15112; the purpose is to increase exposure times on Titan. Apparent overrun over obit visibility occurs only for the WAVECAL exposure, which should not matter. For GO 15112, the STScI edit number 4 caused some problems that were resolved later. -515169056 Assigned ID: 336 ----- Attempting Submission 1 (Fri Apr 08 00:57:48 GMT 2016) ----- HST Phase I Proposal 336 (titanb2.apt) successfully submitted. Receipt: # 336-1 ----- Attempting Submission 2 (Sun Jul 17 19:36:11 GMT 2016) ----- ----- Attempting Submission 3 (Mon Jul 18 20:36:43 GMT 2016) ----- ----- Attempting Submission 4 (Wed Jun 20 18:38:46 GMT 2018) ----- ----- Attempting Submission 5 (Sun Dec 16 23:52:16 GMT 2018) ----- This proposal seeks to use STIS with one orbit each in 2017, 2018, and 2019 to map the full disk of Titan at 1024 wavelengths between 530 and 1000 nm and at 0.05 arc-sec sampling in both spatial dimensions. These observations repeat similar STIS observations between 1997 and 2004 in order to create data sets at opposite seasons. The comparison of the old and new data sets will characterize seasonal asymmetries as function of latitude and wavelength. STIS probes many altitude levels from the surface to the stratosphere eight scale heights higher. Radiative transfer models using previous STIS image cubes resulted in a seasonal model of Titan's haze based on the assumption that Titan is symmetric at opposite seasons. This is probably an approximation, and the proposed data are needed to characterize asymmetries. Cassini's mission is too short to observe Titan at opposite seasons. Ground-based adaptive optics systems do not provide a stable point spread function required to create a suitable data cube. HST is the only telescope that can achieve the goal until the next opportunity around 2047. Characterization of seasonal asymmetries provides one of the most sensitive tests for global circulation models. Titan's seasonal cycle is a vibrant current research topic due to 12 years of Cassini data. This proposal will expand STIS data to a range of 22 years. The opportunity is unique, and the required HST time is minimal. The observations in Cycle 26 will use one orbit providing a full image cube of Titan. The orbit will be similar to the STIS/CCD orbit of GO 14612 taken in Cycle 24 and GO 15112 taken in Cycle 25. The orbit consists of 15 exposures with the grating G750L for wavelengths 530-1000 nm at 0.5 nm/pixel. Each successive exposure is offset by 0.051 arc-sec perpendicular to the slit orientation from the previous one. The aperture is 52X0.05E1. The saved part of the image is 140 spatial rows and all 1024 spectral columns. This avoids buffer dumps during the observation, but still provides plenty of background sky. Calibration exposures are a CCDFLAT and WAVECAL taken at start of Earth occultation. Acquisition is accomplished with a 1 sec exposure with the MIRROR and a F28X50LP aperture using ACQTYPE=DIFFUSE, CHECKBOX=19, DIFFUSE-CENTER=FLUX-CENTRIOD. The same acquisition found Titan's center to better than 0.05 arc-sec in GO 14612. Exposure times will be the longest possible to fit all Titan exposures into the orbit before occultation starts, about 83 sec each. Signal-to-noise levels will be about 50 per pixel in the red continuum. Titan's apparent diameter varies by 20 percent during each year. To optimize spatial resolution I request observations to be scheduled within about one month of opposition that occurs July 9, 2019 and Jul 20, 2020. This gives phase angles of Titan below 3 degrees , as was the case for previous STIS observations. I request to schedule observations during the optimal phase within Titan's 16-day orbit, which is within about two days of Titan's western elongation, when mostly dark terrain faces Earth, and when a STIS image cube was taken in every of the five years of observations. This request is not critical since other orbital longitudes give only a minor degradation of results. Solar System 6 false false false false false false false AVAILABLE SOLAR SYSTEM SATELLITE Satellite Titan STD=SATURN STD=TITAN SEP OF TITAN RHEA FROM EARTH GT 10" EARTH STIS/CCD Spectroscopic No No G750L 7751 POS-TARG MOSAIC DITHER 0.051 STIS-ALONG-SLIT false true 15 0.0 POS-TARG STIS-PERP-TO-SLIT 90.0 1 false 1545003693320 Using ephemeris for target 15490-01-TITAN ephemeris data for target 15490-01-TITAN does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 18.213 to 20.244. ephemeris interval: 18.334 to 20.336 The scheduling data was generated by CASM 26.2.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15490 :visit-id "01" :proposal-version -1 :trans-version "20181130" :date "16-Dec-2018 16:41:32.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 92960 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15490 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15490 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2737 :al-overhead-at-end 0 :internal-dur-at-end 701 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) false 1 0