14916( 2) - 29-Mar-2017 17:40:38 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14916 Version: 2 Check-in Time: 29-Mar-2017 17:40:38 STScI Edit Number: 0 Title Probing methane chemistry in a newly-discovered warm gas giant before JWST ------------------------------------------------------------------------------------ Type Cycle GO 24 ------------------------------------------------------------------------------------ Investigators Contact? PI: Jessica Spake University of Exeter Y CoI: Prof. David Kent Sing University of Exeter N CoI: Dr. Nikolay Nikolov University of Exeter N CoI: Dr. Tom M Evans University of Exeter N CoI: Dr. David Robert Anderson University of Keele N CoI: Dr. Coel Hellier University of Keele N CoI: Prof. Stephane Udry Observatoire de Geneve N CoI: Dr. David Ehrenreich Observatoire de Geneve N CoI: Dr. Gregory W. Henry Tennessee State University N CoI: Dr. Nikku Madhusudhan University of Cambridge N CoI: Mr. Jayesh Goyal University of Exeter N ------------------------------------------------------------------------------------ Abstract WASP-107b is a new, relatively cool (~770K) transiting exoplanet that our team confirmed in January 2017. It has a mass lower than Saturn (0.12MJ), a radius almost as large as Jupiter's (0.94RJ), and a bright host star (H ~ 8.6). These properties make it an outstanding target for transmission spectroscopy. With HST, it will be possible to measure a transmission spectrum rivaling the quality of the canonical planets HD 209458b and HD 189733b. Its low equilibrium temperature places WASP-107b well below the predicted transition from hot, CO-dominated exoplanet atmospheres to cooler, CH4 dominated ones. We propose to use WFC3+G102 and WFC+G141 to measure its near-infrared transmission spectrum. This, combined with allocated K2 photometry will allow us to classify WASP-107b as clear or cloudy, and search for evidence of CH4. If such evidence is detected, WASP-107b would become a prime target for JWST Cycle 1, which is why these observations should be made as soon as possible. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our WFC3 observations will provide a transmission spectrum for the transiting exoplanet WASP-107b across the 0.8-1.1 micron wavelength range. We are targeting the absorption signatures of water and methane. **Observing strategy: To construct the transmission spectrum, we require a single transit of WASP-107b to be observed with WFC3 G102. The observations will be made in slitless spectroscopic mode. Our observing setup is very similar to that used in previous successful exoplanet transit programs, such as for the similar-brightness GJ1214 in Program 13021 (PI Bean). At the start of the HST visit, a standard phase-constrained acquisition image 14916( 2) - 29-Mar-2017 17:40:38 - [ 2] will be taken. The subsequent observing strategy consists of taking repeated exposures for the duration of the transit, plus time before and after the transit to establish the out-of-transit baseline flux. We will use the forward spatial scanning mode with a scan rate of 0.068 arcsec/sec, using SPARS10 and NSAMP=15. We will read out a subarray size of 256 pixels to reduce overheads. Individual exposure times will be 103.1 sec, resulting in a scan across 7.0 arcsec = 54 pixels per exposure, leaving plenty of room on the detector to estimate the background flux. Each transit of WASP-107b lasts 165 minutes. We therefore require 5 consecutive HST orbits. The first orbit serves to allow the telescope to thermally relax into its new pointing position, which is a standard procedure adopted by all HST transiting exoplanet observations. The remaining orbits will provide good phase coverage during transit, and allow for sufficient time (2 HST orbits - one before transit, one after transit) to establish the baseline stellar flux necessary to accurately measure the transit depth. We will obtain 17 science exposures per HST orbit, coming to a total of 34 in-transit and 34 out-of-transit exposures. We choose not to use bi-directional spatial scanning, e.g. as has been done for GJ1214 in Program 13021 (PI Bean). This is because although bi-directional spatial scanning would allow an additional 2 exposures to be acquired per HST orbit (i.e. 19 per orbit), the instrumental systematics are different for each scan direction, which is likely more of a disadvantage. **Signal-to-noise estimates: WASP-107b is a bright target in the conventional sense (V=11.5mag, J=9.4mag). The challenge with exoplanet transmission spectroscopy is to measure subtle changes in the system brightness across different wavelength channels, via variations in the transit depth. We used the HST Exposure Time Calculator with the observational setup described above to calculate a SNR of ~1800 per resolution element per exposure. Note that this flux will be spread over 54 pixel columns due to the spatial scan (see above), so there is no risk of saturation. ------------------------------------------------------------------------------------ 14916( 2) - 29-Mar-2017 17:40:38 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 TYC-5530-179 STAR, EXTRA-SOLAR RA=12H33M32.8480S, J2000 V = 11.47 5-1 PLANETARY SYSTEM, K DEC=-10D08'46.14" V-IV Reference Frame: Other: SIMBAD Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000.0 -0.0065084483324423705 -0.0096 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 14916( 2) - 29-Mar-2017 17:40:38 - [ 4] Visit: 01 (WASP-107 WFC3) Visit Requirements: ORIENT 38D TO 186 D; ORIENT 229D TO 358 D; Period 5.721490 D AND ZERO-PHASE HJD2456514.40982 On Hold Comments: Additional Comments: It is essential that the five HST orbits be scheduled in a contiguous block, free of the SAA. We have defined each HST orbit within a non-interruptible sequence, to ensure that all exposures defined within the sequence are taken during the same HST orbit. We will use forward spatial scanning mode to avoid saturation on relatively long exposures and increase observing efficiency. Visit orientation requirements have been defined to avoid spectra from nearby stars overlapping the target spectrum. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 TYC-5530-17 WFC3/IR MULTIAC GRISM256 F126N NSAMP=3, SAMP-SEQ=RAPID 1 DEF (0.833 PHASE 0.9668 TO 0.9729; 95-1 CUM S) SEQ 1-2 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 2 TYC-5530-17 WFC3/IR MULTIAC GRISM256 G102 NSAMP=15, SAMP-SEQ=SPARS10 16 DEF SPATIAL SCAN 0.068, 90.0 95-1 CUM (1650.058 Degrees, Forward S) ------------------------------------------------------------------------------------------------------------------------------------ 3 TYC-5530-17 WFC3/IR MULTIAC GRISM256 G102 NSAMP=15, SAMP-SEQ=SPARS10 17 DEF SPATIAL SCAN 0.068, 90.0 95-1 CUM (1753.187 Degrees, Forward; SEQ 3 S) NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 4 TYC-5530-17 WFC3/IR MULTIAC GRISM256 G102 NSAMP=15, SAMP-SEQ=SPARS10 17 DEF SPATIAL SCAN 0.068, 90.0 95-1 CUM (1753.187 Degrees, Forward; SEQ 4 S) NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 5 TYC-5530-17 WFC3/IR MULTIAC GRISM256 G102 NSAMP=15, SAMP-SEQ=SPARS10 17 DEF SPATIAL SCAN 0.068, 90.0 95-1 CUM (1753.187 Degrees, Forward; SEQ 5 S) NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 6 TYC-5530-17 WFC3/IR MULTIAC GRISM256 G102 NSAMP=15, SAMP-SEQ=SPARS10 17 DEF SPATIAL SCAN 0.068, 90.0 95-1 CUM (1753.187 Degrees, Forward; SEQ 6 S) NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ TYC-5530-1795-1 1 WFC3/IR MULTIAC GRISM256 F126N none none none none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 1 none 1 N/A CUM 14916( 2) - 29-Mar-2017 17:40:38 - [ 5] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 2 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 3 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 4 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 5 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 6 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 7 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 8 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 9 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 10 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 11 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 12 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 13 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 14 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 15 none 1 N/A CUM TYC-5530-1795-1 2 WFC3/IR MULTIAC GRISM256 G102 none none 16 none 1 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 1 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 2 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 3 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 4 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 5 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 6 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 7 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 8 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 9 none 2 N/A CUM 14916( 2) - 29-Mar-2017 17:40:38 - [ 6] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 10 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 11 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 12 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 13 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 14 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 15 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 16 none 2 N/A CUM TYC-5530-1795-1 3 WFC3/IR MULTIAC GRISM256 G102 none none 17 none 2 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 1 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 2 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 3 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 4 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 5 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 6 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 7 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 8 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 9 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 10 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 11 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 12 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 13 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 14 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 15 none 3 N/A CUM TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 16 none 3 N/A CUM 14916( 2) - 29-Mar-2017 17:40:38 - [ 7] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ TYC-5530-1795-1 4 WFC3/IR MULTIAC GRISM256 G102 none none 17 none 3 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 1 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 2 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 3 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 4 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 5 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 6 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 7 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 8 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 9 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 10 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 11 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 12 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 13 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 14 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 15 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 16 none 4 N/A CUM TYC-5530-1795-1 5 WFC3/IR MULTIAC GRISM256 G102 none none 17 none 4 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 1 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 2 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 3 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 4 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 5 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 6 none 5 N/A CUM 14916( 2) - 29-Mar-2017 17:40:38 - [ 8] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 7 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 8 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 9 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 10 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 11 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 12 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 13 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 14 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 15 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 16 none 5 N/A CUM TYC-5530-1795-1 6 WFC3/IR MULTIAC GRISM256 G102 none none 17 none 5 N/A CUM 14916( 2) - 29-Mar-2017 17:40:38 - [ 9] Summary Form for Proposal 14916 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures GRISM256 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=15, NSAMP=3, SAMP-SEQ=RAPID, SAMP-SEQ=SPARS10 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 229D TO 358 D, ORIENT 38D TO 186 D, PHASE 0.9668 TO 0.9729, Period 5.721490 D AND ZERO-PHASE HJD2456514.40982, SEQ 1-2 NON-INT, SEQ 3 NON-INT, SEQ 4 NON-INT, SEQ 5 NON-INT, SEQ 6 NON-INT, SPATIAL SCAN 0.068, 90.0 Degrees, Forward ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F126N, G102 ------------------------------------------------------------------------------------------------------------------------------------ Target Names TYC-5530-1795-1 ------------------------------------------------------------------------------------------------------------------------------------