14169( 4) - 21-Dec-2015 18:19:42 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14169 Version: 4 Check-in Time: 21-Dec-2015 18:19:42 STScI Edit Number: 2 Title Measuring the absolute H2O abundance of WASP-39b's atmosphere ------------------------------------------------------------------------------------ Type Cycle GO 23 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Hannah Ruth Wakeford NASA Goddard Space Flight Center Y CoI: Prof. David Kent Sing University of Exeter N CoI: Dr. Joanna Barstow University of Oxford N CoI: Dr. Avi Mandell NASA Goddard Space Flight Center N CoI: Dr. Heather A. Knutson California Institute of Technology N CoI: Dr. Tiffany Kataria University of Exeter N CoI: Dr. Nikolay Nikolov University of Exeter N CoI: Dr. Gilda E. Ballester University of Arizona N ------------------------------------------------------------------------------------ Abstract Over the past few years, observations of close-in giant planet atmospheres using WFC3's spectroscopic capabilities have played a pivotal role in the NIR characterization of these worlds. We propose to build upon this success by measuring H2O in the atmosphere of the warm Saturn-mass exoplanet WASP-39b. Our previous optical STIS observations have revealed that WASP-39b has a cloud and haze-free atmosphere, implying that a strong H2O signal will be detectable. Combined with the scattering signature due to H2 that we have measured at shorter wavelengths, our detection will enable us to determine the absolute H2O abundance of the atmosphere. This information is extremely valuable, as it helps to constrain the formation and evolutionary history of the planet, such as the composition of the primordial accretion disk and the planet's location within that disk. Very few H2O abundance measurements for transiting exoplanets are currently available, fewer in which the interpretation is not hindered by clouds or hazes. As such, with a clear atmosphere WASP-39b is uniquely placed to provide an important constraint on its atmospheric chemical abundances. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will use WFC3/IR spectroscopic grism G102 to observe WASP-39 from 0.8 - 1.15 microns over one transit event, with a visit consisting of five consecutive HST orbits. Three orbits will be used to determine the baseline flux, one before and one after transit, while one or two occur during the transit event. We will repeat our successful observing strategies for WFC3 in which we have now perfected very high S/N transit observations in the NIR using spatial scan mode (GO 12473 - Wakeford et al. 2013; Sing et al. 2013; Sing, Wakeford et al. 2015.). During spatial scan mode the telescope is slowly slewed in the cross-dispersion direction while the camera is exposing. This causes the spectra to become spread over a large pixel area of the detector, providing very high S/N levels and vastly improved duty cycles. Spatial scan mode can result in a ten-fold increase in the number of photons per exposure while considerably reducing 14169( 4) - 21-Dec-2015 18:19:42 - [ 2] overheads. This also increases the time of saturation of the brightest pixels, and allows for longer exposure times (McCullough 2011). We also have no roll restrictions, which further eases scheduling. Using the visit planner in APT, we find that WASP-39 has very long yearly observable windows spread throughout the year. For each visit with WFC3 we will use the same observing strategy as our Cycle-19 large program GO-12473, which uses spatial scanning mode to dramatically decrease observational overheads and obtain vastly higher S/N levels. Using WFC3 G141 grism we will observe WASP-39b using spatial scan mode obtaining spectra from 1.1 - 1.7 microns. To reach precisions similar to that of previous HST observations we would require exposure times around 120 seconds spreading the light over around20 pixels with a scan rate of around 0.2 pixels per second, similar to that of XO-1 (V mag = 11.2) and WASP-31 (V mag = 11.7), which are slightly brighter than WASP-39 (V mag = 12.1). This will allow us to achieve S/N levels of around 1300 per exposure when binned up to 4 pixels with roughly 50 in transit exposures with overheads. Using a 256x256 subarray we will avoid systematics observed in the 512x512 subarray (e.g. WASP-17 Mandell, et al., 2013, GJ 1214 Berta et al., 2012), which have time dependent effects on the detector response and persistent ramp-like effects on the data (Swain et al. 2012). Using spatial scan mode instead of stare mode we will also be able to increase the number of observed photons without reaching the non-linearity limit of the detector. ------------------------------------------------------------------------------------ 14169( 4) - 21-Dec-2015 18:19:42 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GSC-04980-00 STAR, EXTRA-SOLAR RA=14H29M18.4080S +/- 0.1", J2000 V = 12.09 761 PLANETARY SYSTEM DEC=-03D26'40.17" +/- 0.1" Reference Frame: Other: SIMBAD Comments: This object was generated by the target selector 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 -8.548776920960978E-4 0.0023 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 14169( 4) - 21-Dec-2015 18:19:42 - [ 4] Visit: 01 Visit Requirements: Period 4.0552782194 D AND ZERO-PHASE HJD2455829.6029470935 On Hold Comments: Additional Comments: transit of WASP-39b, it is essential that the 5 orbits be scheduled in a continuous block 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 GSC-04980-0 WFC3/IR MULTIAC GRISM256 F139M SAMP-SEQ=RAPID, NSAMP=3 1 DEF (0.833 PHASE 0.9531 TO 0.9570 0761 CUM S) Comments: Direct image for wavelength calibration. Phase constrained so transit occurs in orbit 3-4 between 2nd and 3rd contact. ------------------------------------------------------------------------------------------------------------------------------------ 2 GSC-04980-0 WFC3/IR MULTIAC GRISM256 G102 NSAMP=6, SAMP-SEQ=SPARS25 84 DEF SPATIAL SCAN 0.025, 90.0 0761 CUM (9408.673 Degrees, Forward S) Comments: SPATIAL SCAN. Count level/pixel is estimated to be 19, 444 DN from the ETC, following ISR WFC3-2012-08, with a scan rate of 0.025"/sec covering a total of ~2.8". ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GSC-04980-00761 1 WFC3/IR MULTIAC GRISM256 F139M none none none none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 1 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 2 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 3 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 4 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 5 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 6 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 7 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 8 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 9 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 10 none 1 N/A CUM 14169( 4) - 21-Dec-2015 18:19:42 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 11 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 12 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 13 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 14 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 15 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 16 none 1 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 17 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 18 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 19 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 20 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 21 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 22 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 23 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 24 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 25 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 26 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 27 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 28 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 29 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 30 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 31 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 32 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 33 none 2 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 34 none 3 N/A CUM 14169( 4) - 21-Dec-2015 18:19:42 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 35 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 36 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 37 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 38 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 39 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 40 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 41 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 42 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 43 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 44 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 45 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 46 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 47 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 48 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 49 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 50 none 3 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 51 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 52 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 53 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 54 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 55 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 56 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 57 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 58 none 4 N/A CUM 14169( 4) - 21-Dec-2015 18:19:42 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 59 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 60 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 61 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 62 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 63 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 64 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 65 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 66 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 67 none 4 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 68 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 69 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 70 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 71 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 72 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 73 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 74 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 75 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 76 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 77 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 78 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 79 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 80 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 81 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 82 none 5 N/A CUM 14169( 4) - 21-Dec-2015 18:19:42 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 83 none 5 N/A CUM GSC-04980-00761 2 WFC3/IR MULTIAC GRISM256 G102 none none 84 none 5 N/A CUM 14169( 4) - 21-Dec-2015 18:19:42 - [ 9] Summary Form for Proposal 14169 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures GRISM256 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=3, NSAMP=6, SAMP-SEQ=RAPID, SAMP-SEQ=SPARS25 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PHASE 0.9531 TO 0.9570, Period 4.0552782194 D AND ZERO-PHASE HJD2455829.6029470935, SPATIAL SCAN 0.025, 90.0 Degrees, Forward ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F139M, G102 ------------------------------------------------------------------------------------------------------------------------------------ Target Names GSC-04980-00761 ------------------------------------------------------------------------------------------------------------------------------------