fixed the aperture to be the same for both grism and short imaging exposures based on an email from Nor Pirzkal on Oct 11. Please use this for observations. 2095520750 ----- Attempting Submission 4 (Fri Oct 11 18:01:38 GMT 2013) ----- We propose WFC3 G102 and G141 grism spectral imaging of two gravitationally lensed dusty, starburst galaxies found with the 600 square degree Herschel-ATLAS survey. One galaxy is the brightest (both in far-IR at 250 micron and in near-IR in J/K-band), while the second is the largest (11 arcsec on the sky) of the lensed sub-mm galaxies in a sample of 200 imaged with WFC3/F110W. The two galaxies are at redshifts that are optimal for grism observations with HST/WFC3. The lensing flux magnification and spatial enhancement makes them very unique for the study proposed here and will increase the number of lensed galaxies imaged in spectral lines with WFC3 grisms to three from existing single serendipitous lens studied in HST-3D survey. With WFC3 grism spectra taken in a specific orientation to minimize foreground and lensing galaxy confusion we can map each of these galaxies in a variety of spatially-resolved spectral lines in the rest-frame optical, including impostant Balmer lines for studies on the interstellar medium. The grism spectra will allow us to determine the gas-phase metallicities of these two galaxies and to study the extinction of optically-thin regions compared to direct sub-mm emission seen in interferometric continuum images of optically thick dust in starbursting knots and clumps. With spatial resolution provided by gravitational lensing combined with HST/WFC3 resolution, we will be able to study the dependence of line ratios in high density/SFR regions to low dense diffuse environments. The program is related to rest-frame optical spectro-imaging of two lensed starbursting galaxies (G15.19 at z=1.06 and NB.43 at z=1.667) found with Herschel. The two lensed galaxies are near-IR bright and spans 3 arcsec Einstein ring in G15.19 to a giant arc of 11 arcsec long in NB.43. The most basic goals of this program are (i) Obtain spatially resolved imaging in multiple spectral lines to study the line intensity variations across two starburst galaxies within the ISM in at least 20 spatial resolution elements (i.e., independent spectral pixels). (ii) Derive extinction corrections using either Halpha/Hbeta (G15.19 at z = 1.026) or Hbeta/Hgamma (NB.43 at z = 1.677) at multiple locations within the galaxy. Compare and contrast with the spatial distribution of optically-thick dust extinction directly seen with high-resolution sub-mm dust emission maps from ALMA (G15.19) and SMA (NB.43/G15.19). (iii) Derive gas-phase metallicities of these two galaxies with either R23 or O23 ratios, and study any differences in the rest UV and optical line intensities and line ratios relative to the gas and SFR surface densities of these galaxies derived from mm-wave interferometeric observations. To achieve these science goals we make use of both G141 and G102 grisms of WFC3. To align grism spectra on the sky we also take deep images following the guidelines of the WFC3 handbook. We use F160W and F105W. We have used the on-line calculator to estimate the exposure time necessary to detect the Halpha or Hbeta from each of the G102 or G141 spectra of the two sources. The times are such that we need to spend 2 orbits on G15.19 and 3 orbits on NB.43. To minimize the source overlap in grism spectra and to separate the lensed starbursting galaxy from the foreground lens, these grism observations require certain ranges in orientation. These were described in the original science proposal. We do not need to do orthogonal grism observations as the sources we are studying are bright and the contamination can be minimized over a range of PA. The request ranges were calculated based on the orientation and the angle between the WFC3/grism dispersion direction and the U3 roll angle. To allow a range of possible scheduling options, we have left +/- 30 degrees from the preferred position angle for observations. COSMOLOGY 12 false false 0.0 0.0 false false false SUPPORTED GALAXY GRAVITATIONAL LENS STARBURST J2000 J2000 K-band AB = 18 GALAXY GRAVITATIONAL LENS STARBURST J2000 J2000 K-band AB = 20.5 WFC3/IR Spectroscopic No No G141 WFC3/IR Spectroscopic No No G102 WFC3/IR Spectroscopic No No G102 WFC3/IR Spectroscopic No No G141 POS-TARG DITHER 0.636 LINE false false 2 41.788 WFC3-IR-DITHER-LINE 1 false The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. /private/var/folders/kn/pslb0xt88v55zk006s6hv7mr0000gn/T/OPVisit1930098873777726000.xml 1381514406558 52 (Tic-Visit :proposal-id 13399 :visit-id "01" :proposal-version -1 :trans-version "20130502" :date "11-Oct-2013 11:00:05.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1357872 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13399 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13399 :visit-id "01" :orbit-number 1 :pcs-time 241 :si-vis-utilization 2744 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3120.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13399 :visit-id "01" :orbit-number 2 :pcs-time 176 :si-vis-utilization 2870 :al-overhead-at-end 0 :internal-dur-at-end 690 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3120.0 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 21.2. 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