We propose to characterize the conditions, composition, and chemistry in two transiting exoplanet atmospheres using molecules as probes. This will be accomplished through high precision, near-IR spectroscopy during an interval that spans the primary and/or secondary eclipse events. We have selected the hot-Jovian HD 209458b and the warm-Neptune GJ 436b for spectroscopy from 1.4 to 2.5 microns and we expect to detect the molecules H2O, CH4, CO, CO2, and NH3. We will infer the atmospheric temperature-pressure profiles and determine the abundance of detected molecules; this will be done by comparing detailed radiative transfer models with emission and transmission spectra of the exoplanet atmospheres. Taken together with the existing observations of HD 189733b, the proposed measurements will probe the diversity of exoplanet atmospheres and the effects of radiation from the stellar primary.

We propose to observe (1) HD 209458b in both primary and secondary eclipses and (2) GL 436b in primary eclipse. In all cases, we will observe the targets both prior to and following the event in order to establish a good baseline. Since the measurements are demanding and must achieve a very high signal to noise (after removal of the inevitable systematics), we require that NICMOS be used in a special mode designed for such observations. Our observations of HD 189733b demonstrated a signal-to-noise ratio of 10^4 per channel in 50 nm-wide spectral channels. This was achieved only after proper modeling and removal of systematics, and is within ~1.2 of the theoretical detection noise limit. The details of this optimization are contained in the Supplementary Information to Swain et al. 2008b. However, successful removal of the systematics can only be achieved if the effect of these on the photometry is small to start with. This requires a stable instrument configuration. The observation description is from the phase 1 proposal. The awarded time is 15 orbits for primary eclipse observations of HD 209458b. The observations must be phased to the primary eclipse event(s) of this transiting exoplanet. Since the orbital period is every 3.5 days, there are numerous scheduling opportunities. EXTRA-SOLAR PLANETS 3 false 0.0 0.0 false false false false false AVAILABLE STAR EXTRA-SOLAR PLANET EXTRA-SOLAR PLANETARY SYSTEM This object was generated by the targetselector and retrieved from the SIMBAD database. K=6.62 J2000 22 03 10.8000 +18 53 4.00 J2000 NIC3 Imaging No No F190N NIC3 Imaging No No F215N NIC3 Spectroscopic No No G206 NIC3 Imaging No No F190N NIC3 Imaging No No F215N NIC3 Spectroscopic No No G206 NIC3 Imaging No No F190N NIC3 Imaging No No F215N NIC3 Spectroscopic No No G206 NIC3 Imaging No No F190N NIC3 Imaging No No F215N NIC3 Spectroscopic No No G206 NIC3 Imaging No No F190N NIC3 Imaging No No F215N NIC3 Spectroscopic No No G206 NIC3 Imaging No No F190N NIC3 Imaging No No F215N NIC3 Spectroscopic No No G206 start HD209458 primary eclipse G206 spectra - visit is 5 orbits long with primary eclipse viewed in orbits 3 & 4 - constraint roll angle held constant 1213522229000 239.76878408130463 (Tic-Visit :proposal-id 11512 :visit-id "01" :proposal-version -1 :trans-version "20071214" :date "22-Apr-2008 13:54:08.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 7209264 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11512 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 11512 :visit-id "01" :obset-id "A1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11512 :visit-id "01" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2676 :al-overhead-at-end 0 :internal-dur-at-end 141 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11512 :visit-id "01" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2785 :al-overhead-at-end 0 :internal-dur-at-end 116 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11512 :visit-id "01" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2785 :al-overhead-at-end 0 :internal-dur-at-end 116 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11512 :visit-id "01" :orbit-number 4 :pcs-time 355 :si-vis-utilization 2751 :al-overhead-at-end 0 :internal-dur-at-end 135 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11512 :visit-id "01" :orbit-number 5 :pcs-time 355 :si-vis-utilization 2772 :al-overhead-at-end 0 :internal-dur-at-end 91 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) false 5 0 start HD209458 primary eclipse G206 spectra - visit is 5 orbits long with primary eclipse viewed on orbit 3 - constraint roll angle held constant 1219788338000 175.0 false -1 -1 start HD209458 primary eclipse G206 spectra - visit is 5 orbits long with primary eclipse viewed on orbit 3 - constraint roll angle held constant 1219190084000 182.68285079806756 (Tic-Visit :proposal-id 554 :visit-id "03" :proposal-version -1 :trans-version "20080624" :date "22-Jul-2008 10:33:18.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 6397584 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 554 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 554 :visit-id "03" :obset-id "A3" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 554 :visit-id "03" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2493 :al-overhead-at-end 0 :internal-dur-at-end 141 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) (Tic-Orbit :proposal-id 554 :visit-id "03" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2408 :al-overhead-at-end 0 :internal-dur-at-end 91 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) (Tic-Orbit :proposal-id 554 :visit-id "03" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2434 :al-overhead-at-end 0 :internal-dur-at-end 135 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) (Tic-Orbit :proposal-id 554 :visit-id "03" :orbit-number 4 :pcs-time 355 :si-vis-utilization 2408 :al-overhead-at-end 0 :internal-dur-at-end 91 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) (Tic-Orbit :proposal-id 554 :visit-id "03" :orbit-number 5 :pcs-time 355 :si-vis-utilization 2505 :al-overhead-at-end 0 :internal-dur-at-end 91 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) false 5 0 start HD209458 primary eclipse G206 spectra - visit is 5 orbits long with primary eclipse viewed on orbit 3 - constraint roll angle held constant This is a repeat of failed visit 03. (Tic-Visit :proposal-id 554 :visit-id "03" :proposal-version -1 :trans-version "20080624" :date "22-Jul-2008 10:33:18.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 6397584 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 554 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 554 :visit-id "03" :obset-id "A3" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 554 :visit-id "03" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2493 :al-overhead-at-end 0 :internal-dur-at-end 141 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) (Tic-Orbit :proposal-id 554 :visit-id "03" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2408 :al-overhead-at-end 0 :internal-dur-at-end 91 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) (Tic-Orbit :proposal-id 554 :visit-id "03" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2434 :al-overhead-at-end 0 :internal-dur-at-end 135 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) (Tic-Orbit :proposal-id 554 :visit-id "03" :orbit-number 4 :pcs-time 355 :si-vis-utilization 2408 :al-overhead-at-end 0 :internal-dur-at-end 91 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) (Tic-Orbit :proposal-id 554 :visit-id "03" :orbit-number 5 :pcs-time 355 :si-vis-utilization 2505 :al-overhead-at-end 0 :internal-dur-at-end 91 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) false 5 0