Assigned ID: 1111 ----- Attempting Submission 1 (Mon May 21 16:35:18 GMT 2012) ----- ----- Attempting Submission 1 (Thu Aug 30 08:35:16 GMT 2012) ----- Between February and April 2012, we have detected and confirmed a new exoplanet transiting the bright (J=8.8, H=8.2) M dwarf GJ 3470 (Bonfils et al., submitted): with a mass of 13.3+/-1.6 M_Earth and a radius of 4.2+/-0.7 R_Earth, this exoplanet is a rare beast at the boundary between super-Earths and Neptunes. Its weak density suggests that it can have a thick hydrogen and helium atmosphere, and thus a large atmospheric scale height. Combined with the proximity and brightness of its red dwarf host, this makes the planet an excitingly favorable target for atmospheric characterization with HST. In particular, the 1.4-µm water band defining the boundary between J and H bands for ground-based observations, thus non-detectable from the ground, is well detectable with WFC3 in case of an H/He atmosphere with solar composition, which is the favored hypothesis for a sub-Neptune. In contrast, a non-detection of this water band would imply (i) a surprisingly water-rich atmosphere - in which case GJ 3470b would rather be a giant ocean-planet, bridging together the super-Earth and Neptune classes, or (ii) the presence of high-altitude clouds or hazes. A non-detection would thus motivate complementary observations of scattering signatures in the optical. These observations consist in one visit of 5 consecutive orbits aimed at obtaining a low-resolution transit spectrum of the exoplanet GJ 3470b. The first exposure in the first orbit of the visit has timing constraints set so that the third HST orbit precisely occurs during the transit of the exoplanet. In each orbit, we will observe a sequence of G141 grism exposures. F130N direct images will also be taken at the start and end of each orbit. Both grism and direct images will be taken with the GRISM512 aperture. No dithering is to be done at any point during these observations: we need to keep the target in the same position on the detector to obtain the best possible accuracy for this differential measurement. EXTRA-SOLAR PLANETS 0 false 0.0 0.0 false false false false SUPPORTED STAR M V-IV This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 J=8.79 mag, H=8.21 mag, K=7.99 mag WFC3/IR Spectroscopic No No G141 1346315572432 /private/var/folders/n0/fszwvj4s67ng55v_317dpf940000gn/T/OPVisit1084407635187241367.xml The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 13064 :visit-id "01" :proposal-version -1 :trans-version "20120604" :date "30-Aug-2012 16:32:39.0" :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 6452704 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13064 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13064 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2125 :al-overhead-at-end 0 :internal-dur-at-end 738 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3244 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13064 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2986 :al-overhead-at-end 0 :internal-dur-at-end 281 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3244 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13064 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2944 :al-overhead-at-end 0 :internal-dur-at-end 241 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3244 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13064 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2944 :al-overhead-at-end 0 :internal-dur-at-end 241 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3244 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13064 :visit-id "01" :orbit-number 5 :pcs-time 222 :si-vis-utilization 2944 :al-overhead-at-end 0 :internal-dur-at-end 230 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3244 :pcs-gap 0 ) true 5 0