0 Assigned ID: 566 ----- Attempting Submission 1 (Fri Apr 08 16:13:15 GMT 2016) ----- HST Phase I Proposal 566 (phase1-GO_v1.pdf.apt) successfully submitted. Receipt: # 566-1 ----- Attempting Submission 2 (Fri Apr 08 23:40:43 GMT 2016) ----- 0 ----- Attempting Submission 1 (Wed Jul 20 03:51:55 GMT 2016) ----- We have recently discovered a remarkable concentration of massive galaxies at z=2.506 in the COSMOS field, containing 11 very red galaxies within a 10'' radius, defining a 11.6sigma overdensity. The total stellar mass M* ~ 10^{12} Msun found within 80 kpc is consistent with a core of a dark matter halo with total mass M_{200c} ~ 10^{14} Msun, as further confirmed with extended X-ray emission and velocity dispersion (16 spectroscopic members), identifying it as the most distant galaxy cluster known to date. However, unlike other clusters discovered so far the red galaxies in this structure are virtually all star forming with a total star formation rates (SFR) ~3400Msun yr^{-1} in its 80 kpc-wide core, suggesting that it was caught in a rapid formation phase of a dense cluster core. Hence this structure provides a rare chance to witness the build-up of the cluster central galaxies, and explore environmental effects on massive galaxy evolution in the densest environment. Here we propose WFC3 F125W and F160W imaging (rest-frame U and B band, respectively) of this structure to push the study of mass-size relation and SFR-morphology relation for cluster galaxies to the highest redshift. These observations of this unique structure will provide crucial insights on the interplay between morphological transformation and star formation quenching in cluster cores. WFC3 F125W and F160W imaging of a distant galaxy cluster at z=2.5 Galaxies Intergalactic Medium and Cosmology 12 false false false false false false SUPPORTED CLUSTER OF GALAXIES HIGH REDSHIFT CLUSTER INTERACTING GALAXY RICH CLUSTER NO J2000 J2000 WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F125W POS-TARG DITHER 0.572 LINE 0.365 false false 74.653 4 18.528 WFC3-IR-DITHER-BOX-MIN 2 false 1468986582724 /Users/twang/Dropbox/Latex/proposal/HST/cycle24/OP-cache/phase2-v01.xml The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14750 :visit-id "01" :proposal-version -1 :trans-version "20160601" :date "20-Jul-2016 11:49:42.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 3063936 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14750 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14750 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2829 :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 3210 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14750 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2829 :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 3210 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14750 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2829 :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 3210 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14750 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2829 :al-overhead-at-end 0 :internal-dur-at-end 462 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3210 :pcs-gap 0 ) true 4 0