Near-IR spectroscopy of the newly discovered benchmark hot Jupiter WASP-103b

0 Assigned ID: 503 ----- Attempting Submission 1 (Fri Apr 11 14:46:31 GMT 2014) ----- HST Phase I Proposal 503 (wasp-103.apt) successfully submitted. ----- Attempting Submission 2 (Fri Apr 11 20:44:11 GMT 2014) ----- HST Phase I Proposal 503 (wasp-103.apt) successfully submitted. Updated version. -1990499269 ----- Attempting Submission 1 (Wed Jul 23 05:12:26 GMT 2014) ----- HST Phase II Proposal 13660 (13660.apt) successfully submitted. ----- Attempting Submission 2 (Thu Jul 24 06:15:25 GMT 2014) ----- Near-IR spectroscopy of the newly discovered benchmark hot Jupiter WASP-103b We propose to use the WFC3 IR-G141 grism to measure the near-IR emission spectrum of the newly discovered hot Jupiter WASP-103b at secondary eclipse. WASP-103b is one of the three best targets for thermal emission spectroscopy, but is the only one with no existing data of any kind. It receives relatively little far UV flux from its early-type host star as compared to other hot Jupiters, implying potentially different atmospheric chemistry. Because understanding the complex physics and chemistry of planetary atmospheres requires high significance, high fidelity measurements, WASP-103b provides an essential benchmark for testing planetary atmosphere models. The high quality WFC3 observations will definitively determine the presence or absence of a thermal inversion in the planet's upper atmosphere and constrain the efficiency of heat recirculation to its night side by probing the water bands between 1.1-1.7 microns. When combined with complementary ground-based and Spitzer measurements at longer wavelengths these observations will also provide constraints to the C/O ratio of the atmosphere. They will therefore provide insight on whether or not some hot Jupiters have C/O ratios that deviate from those of their host stars. This study can only be done with HST because of the ultra-high precision requisite for meaningful model constraints, and the coverage of water bands that are critical for constraining elemental compositions but are inaccessible from the ground. We plan to use the WFC3 IR camera and the G141 grism in the 256x256 pixel subarray mode to provide slitless spectroscopy at wavelengths from 1.1 to 1.7 micron. We will observe in the spatial-scan mode to spread out the spectrum by slowly slewing the telescope perpendicular to the dispersion direction. This mode increases the observing duty cycle by a factor of 1.6 for WASP-103b from 46% in the "staring" mode to 74% by using SPARS10 and NSample=8 (texp=51.7 sec). We chose SPARS10 instead of SPARS25 because the latter would not increase the observing efficiency and the number of multi-sample is lower and thus not optimal for cosmis ray rejection. We will alternate between forward and reverse scan directions in order to further reduce overheads. We will scan at a rate of 0.025 arcsec/s and spread the target over a vertical range of ~2 arcsec. This is to ensure the spread of the spectra is not too wide, so cosmic ray and bad pixel contamination can be limited. The predicted peak counts of the spatial scan is 13,700 DN/pix based on the ETC's brightest pixel in e-, which is low enough to avoid the "hook" effect in exposures (i.e., first exposure counts < 10,000 DN/pix, Wilkins et al. 2014). The minimum scan rate below saturation, based on McCullough & MacKenty (2012), is ~0.01 arcsec/s. -------- Realtime Justification -------- Due to the nature of planetary transits and eclipses, our proposed observations are only available at certain time windows when the planet passes behind its host star (P = 0.925542+/- 0.000019 days). Our observations are thus time critical! The the eclipse duration of WASP-103b is 2.6 hours. To reach our science goal, we require 2 orbits to cover the pre-eclispe baseline (1 orbit will be discarded following the standard procedure to allow the telescope to stabilize). We will need 2 orbits to fully cover both the ingress, full-eclipse, and egress part of the light curve. We also need another 1 orbit to cover the post-eclipse baseline. So the total is 5 orbits per visit. Each visit must consist of 5 SAA-free (or hidden) and consecutive HST orbits! For wavelength calibration purpose, we require one direct, un-dispersed image to be taken at the beginning of each visit, followed by consecutive (uninterruptible) grism exposures throughout the visit. The position of the targets in the un-dispersed image should be the same as the grism exposures. EXTRA-SOLAR PLANETS 12 Regular false false false false false SUPPORTED STAR EXTRA-SOLAR PLANETARY SYSTEM F3-F9 This object was generated by the targetselector and retrieved from the SIMBAD database. WASP-103 J2000 J2000 K=10.76 +/= 0.020 WFC3/IR Spectroscopic No No G141 1406181951073 Phase windows are not calculated when the gap between schedulable intervals is less than 1 days, assuming no scheduling restrictions for constraint Phase 0.294/0.312. The scheduling data was generated by CASM 22.2. CASM was run in Phase II mode. 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The scheduling data was generated by CASM 22.2. CASM was run in Phase II mode. 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