Clumps of star formation spreading widely in galactic disks are common features of star-forming galaxies at 1 < z < 3. This is the epoch when galaxy assembly activities peaked. These clumps could represent a pathway through which a majority of the stellar mass in the Universe was formed; understanding their formation and evolution is central to our understanding of galaxy evolution. However, the intensely star-forming clumps in disk galaxies at z ~ 2 have rarely been studied. Each of these clumps is forming stars in situ at a rate comparable to the most luminous merger-triggered starbursts in the local Universe. They are thus unique test cases to study the mechanism that drives intense star formation at z ~ 2. We propose WFC3 near-IR imaging and spatially-resolved spectroscopy of a gravitationally lensed, kinematically ordered, vigorously star-forming galaxy at z = 1.885 with physical resolutions up to 40 pc. This galaxy contains two luminous clumps that are forming stars at the rates of 100 solar mass/yr/clump. Spatially-resolved map of star formation from HST provides the most critical missing piece to interpret our existing observations of this galaxy in far-IR, CO emission lines, and radio continuum. We will probe the frontier research areas in z ~ 2 star formation, particularly the spatially-resolved star formation laws and dynamics of cold and ionized gases, which have never been probed at this spatial resolution. Our proposed observations will provide a benchmark against which to interpret the structures of vigorous star-forming clumps in general. This object can therefore have a unique impact on our understanding of the star-forming modes that dominate at z ~ 2. We are observing a 2" Einstein ring image of a star-forming galaxy at z ~ 2 using WFC3 imaging and grism spectroscopy to obtain spatially-resolved color and H-beta/[OIII] variations, respectively. We set up this observation in two different ORIENT angles, each with 4.8 ks of G141 spectroscopy divided into 4 exposures (2 per orbit, 8 grism exposures total). Each G141 exposure is preceded by either F105W (6 exposures) or F140W (2 exposures) direct imaging (the target is fainter in F105W). We follow dithering strategy of program# 12177 (3D-HST, PI: van Dokkum), i.e., POS-TARG: (0, 0) (1.355, 0.424) (0.881, 1.212) (-0.474, 0.788) The narrow ORIENT requests (ORIENT-A = 237-249 deg, ORIENT-B = 165-185 deg) are to (1) avoid the 0th and 1st-order images from nearby bright objects, (2) avoid dispersing the elliptical lens galaxy onto the bright regions of the Einstein ring, and (3) avoid dispersing the bright regions of the Einstein ring onto themselves. UNRESOLVED STELLAR POPULATIONS AND GALAXY STRUCTURE Default false false false false false SUPPORTED GALAXY EINSTEIN RING STARBURST ULTRALUMINOUS IR GAL J2000 J2000 F140W = 23.1 mag, F105W = 23.7 mag WFC3/IR Imaging No No F140W WFC3/IR Spectroscopic No No G141 WFC3/IR Imaging No No F105W WFC3/IR Spectroscopic No No G141 The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 13411 :visit-id "01" :proposal-version -1 :trans-version "20130502" :date "17-Jun-2013 17:01:36.0" :trans-errors '(:WARNINGS 4 :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 1706048 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13411 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13411 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2950 :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 3287 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13411 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3062 :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 3287 :pcs-gap 0 ) false 2 0 The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 13411 :visit-id "03" :proposal-version -1 :trans-version "20130502" :date "17-Jun-2013 16:51:38.0" :trans-errors '(:WARNINGS 4 :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 1706048 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13411 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13411 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2950 :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 3287 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13411 :visit-id "03" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3050 :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 3287 :pcs-gap 0 ) true 2 0