one small fix. 1458973740 Assigned ID: 639 ----- Attempting Submission 1 (Fri Apr 11 18:06:14 GMT 2014) ----- HST Phase I Proposal 639 (ring22.apt) successfully submitted. ----- Attempting Submission 2 (Fri Apr 11 18:09:00 GMT 2014) ----- 0 ----- Attempting Submission 1 (Wed Jul 23 05:45:58 GMT 2014) ----- We propose WFC3 optical and infrared imaging of the largest, nearly-complete Einstein ring known. The ring has an extreme diameter, approximately 20 arcseconds, and is the result of gravitational lensing by a massive cluster elliptical galaxy at z = 0.36. This spectacular system shows two source galaxies (perhaps interacting), resulting in double arcs with striking differences in color. The proposed high resolution images will unveil detailed structure in the ring arcs (which exhibit a complex structure), allowing for the identification of multiply imaged regions in the source galaxies. Modelling the images over the full range of position angles around the rings will provide the best constraints on the lens mass distribution, and will connect observations and models from galaxy to cluster scales. These data will allow for the study of spatially resolved star-formation in the source galaxies, and enable additional followup through a more democratic window to the high-redshift Universe. The ring features observed in the ground-based images range in surface brightness from 24 to 25 AB mag/arcsec^2 in Sloan g, and 23 to 24 AB mag/arcsec^2 in i. To achieve a S/N ~ 5 for the faintest of these in a 0.2 arcsec radius aperture requires ~1000 sec in F555W and F775W with WFC3/UVIS according to the WFC3 ETC; with overhead this corresponds to one orbit for the optical observations. We choose WFC3/UVIS rather than ACS/WFC to get the best possible spatial resolution (smaller pixels); to this end we will employ a standard dither pattern to subsample and eliminate pixel artifacts. We will also obtain one orbit of WFC3/IR F160W imaging to study at high resolution the red arcs that are bright in the IR and potentially find more distant lensed images. Coordinated parallel observations with ACS/WFC in F475W, F625W, and F775W will probe the lensing cluster environment, and a foreground cluster. COSMOLOGY Default false false false false false SUPPORTED CLUSTER OF GALAXIES EINSTEIN RING GRAVITATIONAL LENS J2000 J2000 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F775W WFC3/IR Imaging No No F160W ACS/WFC Imaging No No F475W ACS/WFC Imaging No No F625W ACS/WFC Imaging No No F775W ACS/WFC Imaging No No F850LP 1405834834639 /Users/saurabh/proposals/hst.cycle22.ring/phase2/OP-cache/ring22-phase2-v01.xml The scheduling data was generated by CASM 22.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 13756 :visit-id "01" :proposal-version -1 :trans-version "20140605" :date "20-Jul-2014 01:40:33.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 3974496 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13756 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13756 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2945 :al-overhead-at-end 116 :internal-dur-at-end 699 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3278 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13756 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3040 :al-overhead-at-end 0 :internal-dur-at-end 866 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3278 :pcs-gap 0 ) true 2 0