0 Assigned ID: 1329 ----- Attempting Submission 1 (Tue Jan 31 17:03:30 GMT 2017) ----- added proper motion for target 536946114 ----- Attempting Submission 2 (Wed Mar 29 18:29:28 GMT 2017) ----- ----- Attempting Submission 3 (Sun Apr 30 11:12:59 GMT 2017) ----- WASP-107b is a newly announced transiting planet that is the highest signal-to-noise target for transmission spectroscopy discovered in the last decade, thanks to its low surface gravity and small, bright host star. The planet is in the intriguing transition region between ice and gas giants, with a mass comparable to Neptune and a radius similar to Jupiter. Relative to other benchmark systems, WASP-107b has a cool equilibrium temperature (780 K), where methane and water are both expected to be abundant. The planet therefore provides a unique opportunity for spectroscopic characterization of carbon and oxygen chemistry. With its large expected signal, WASP-107b also provides an excellent laboratory to study aerosol formation. The features are so large that even if thick clouds/haze are present at very high altitudes (0.1 mbar), it will still be possible to detect absorption features peeking out above them. Here we propose a reconnaissance observation of a single transit of WASP-107b. This measurement will vet the planet's atmosphere composition and test for the presence of aerosols so that the community can decide on the best follow-up strategy for this exciting system. We will obtain time series spectroscopy of the WASP-107b planetary system with the WFC3 instrument during one transit of the planet. We will use the G141 grism and the 256x256 subarray. The observation will consist of five sequential HST orbits to obtain quasi-continuous coverage of the planet's transit. Following common practice, we will use the first orbit in the visit as a burn-in to decrease instrument systematics. The remaining four orbits are required to observe the transit and measure the out-of-transit baseline flux level. We will obtain a direct image of the target star with the F130N filter at the beginning of each orbit for wavelength calibration. The remainder of each orbit will consist of 112 s exposures with the NSAMP = 6, SPARS25 readout pattern. To keep the fluence near 30,000 photoelectrons, we will use spatial scan mode with a 0.134 arcsec/sec scan rate (yielding a total scan height of 124 pixels). To maximize the duty cycle of the observations, we will alternate between forward and reverse scanning along the detector. We calculated the optimal scan parameters using the open-source PandExo_HST python package, which is based the observational design from past HST programs that yielded photon-limited light curves. Extrasolar Planets and Planet Formation 0 false false false false false false SUPPORTED STAR EXTRA-SOLAR PLANETARY SYSTEM This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 WFC3/IR Spectroscopic No No G141 1493550756487 The scheduling data was generated by CASM 25.0. CASM was run in Phase II mode. /private/var/folders/5j/qwc6_lgn4rz5sphtd1gssl340000gn/T/OPVisit3305963965283409037.xml (Tic-Visit :proposal-id 14915 :visit-id "01" :proposal-version -1 :trans-version "20170109" :date "30-Apr-2017 13:12:30.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 813728 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14915 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14915 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2778 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3218 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14915 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2929 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3218 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14915 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2929 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3218 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14915 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2929 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3218 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14915 :visit-id "01" :orbit-number 5 :pcs-time 222 :si-vis-utilization 2929 :al-overhead-at-end 0 :internal-dur-at-end 408 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3218 :pcs-gap 0 ) true 5 0