Final version v5. -2096207235 Assigned ID: 264 ----- Attempting Submission 1 (Thu Apr 10 21:36:28 GMT 2014) ----- HST Phase I Proposal 264 (W0458.apt) successfully submitted. ----- Attempting Submission 2 (Fri Apr 11 21:39:32 GMT 2014) ----- HST Phase I Proposal 264 (W0458.apt) successfully submitted. ----- Attempting Submission 3 (Fri Apr 11 23:52:38 GMT 2014) ----- HST Phase I Proposal 264 (W0458.apt) successfully submitted. ----- Attempting Submission 4 (Sat Apr 12 00:18:34 GMT 2014) ----- HST Phase I Proposal 264 (W0458.apt) successfully submitted. ----- Attempting Submission 5 (Sat Apr 12 00:40:42 GMT 2014) ----- HST Phase I Proposal 264 (W0458.apt) successfully submitted. ----- Attempting Submission 6 (Sat Apr 12 01:24:46 GMT 2014) ----- HST Phase I Proposal 264 (W0458.apt) successfully submitted. ----- Attempting Submission 7 (Sat Apr 12 01:27:57 GMT 2014) ----- Resubmitting adding a before and after and correcting the orient angle to 160 degrees. -1707409264 ----- Attempting Submission 1 (Mon Jul 14 23:24:56 GMT 2014) ----- ----- Attempting Submission 2 (Thu Jul 24 21:41:04 GMT 2014) ----- ----- Attempting Submission 3 (Mon Sep 29 17:06:03 GMT 2014) ----- Using the G141 WFC3/IR grism, we propose a HST spectrophotometric monitoring study of the coolest variable brown dwarf (~650K) identified as part of our Brown dwarf Atmosphere Monitoring (BAM) program. The proposed observations will enable exploration of the dynamic atmospheric evolution of a benchmark T8.5 binary brown dwarf system, which we have discovered to exhibit the second-largest amplitude variation amongst all currently known brown dwarf variables. The close binarity of this system requires the exquisite stability of the HST point spread function to enable resolved monitoring of both components and to discriminate the source of the variability - the second component is a planetary mass object based on evolutionary models. This BAM follow-up study is designed to characterize both the longitudinal and vertical structure of the atmospheric properties of this system via multi-wavelength observations covering the entire spectral range of the WFC3/IR detector. Additionally, by monitoring the target over two separate epochs we will measure the evolution of atmospheric features giving rise to the flux variations. The proposed program will provide a comprehensive dataset serving as a benchmark comparison to directly imaged planets, intensely irradiated Hot Jupiters, and synthetic atmospheric models incorporating different physical processes. We are observing W0458+6434, a T8.5 binary brown dwarf system detected by the WISE satellite, with the HST/WFC3 infra-red camera using the G141 grism. This program intends to resolve the spectra of both binary components and perform spectrophotometric monitoring of this system over four HST orbits. To resolve the spectra of the two binaries we need to have the binaries oriented at 0 or 180 degrees with respect to the y-axis in the detector frame given by the ORIENT keyword using the equation below, ORIENT = PA_y + 180 - 44.59, where, PA_y is the angle by which the FoV needs to be rotated to align the binaries parallel to the y-axis. For W0458, this angle is approx. 25 degrees, suggesting the optimal ORIENT to be 160 degrees. Additionally, we intend to observe the target in the Continuous Viewing Zone, which combined with the above ORIENT restriction is available in three 2-day windows over the duration of the entire current HST cycle. The two components of this binary system are separated by 0.25 arcsec or ~2px. After discussion with the WFC3 CS, we determined that doing a dither pattern and drizzle combination for these observations would not be useful. The separation is sufficient for the extraction of each individual target. Also, previous WFC3/IR proposals have gained significantly by ensuring the objects were maintained on a single pixel throughout the observations, limiting systematic effects. We are thus observing the target in the 256px sub-array mode with one F140W image taken for calibration purposes at the start of each orbit, followed by the G141 grism exposures. The exposure times have been selected to ensure SNR > 100 in the fainter component (J~18.5 mag) at the J-band peak (1.28um). COOL STARS Default false false false false false SUPPORTED STAR BROWN DWARF EXTRA-SOLAR PLANETARY SYSTEM This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 A - J = 17.50, H = 17.8, B - J = 18.5, H = 18.8 WFC3/IR Spectroscopic No No G141 WFC3/IR Imaging No No F098M WFC3/IR Spectroscopic No No G141 WFC3/IR Imaging No No F098M 1412010249976 The scheduling data was generated by CASM 22.2. CASM was run in Phase II mode. /private/var/folders/qy/709xg2753s94x08z_jbxjwnc0000gp/T/OPVisit3740249969624799132.xml (Tic-Visit :proposal-id 13705 :visit-id "01" :proposal-version -1 :trans-version "20140605" :date "29-Sep-2014 10:04:08.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1286480 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13705 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :cvz T :proposal-id 13705 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 21883 :al-overhead-at-end 0 :internal-dur-at-end 354 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 0 :low-sky "N" :pcs-visibility 0 :pcs-gap 0 ) true 4 0