Merging clusters of galaxies are beginning to provide constraints on fundamental physics, such as the dark matter self-interaction cross-section and the matter/antimatter ratio. We request joint Chandra and HST imaging to examine a merger at z=0.53 which we have identified optically and spectroscopically confirmed. Our optical data and weak lensing mass map clearly show three sub-clusters within the same redshift range, while our SZ data are consistent with an offset between the hot ICM and sub-clusters; Combined HST and Chandra imaging are needed to confirm this offset and provide accurate displacements between X-ray-emitting gas, galaxies, and mass which can constrain the physics of merging clusters. The requested observations will also facilitate a wide range of non-merger science.

We will perform a coordinated parallel observation with ACS/WFC as the primary and WFC3/UVIS as the secondary. Our program consists of a modified two point ACS/WFC mosaic with three orbits per pointing (two with F814W and one with F606W) with simultaneous WFC3/UVIS exposures (two with F814W and one with F606W). In order to place the WFC3/UVIS field-of-view as close to the third subcluster as possible without compromising the primary ACS observations of the two main subclusters we will require an orientation constraint of +/- 5 degrees for each pointing. A three exposure per orbit program is required by buffer limitations in order to fully utilize of each orbit. For the F814W orbits we will use an ACS/WFC box dither pattern that performs a 1/2 subpixel sampling, covers the chip gaps of ACS/WFC and WFC3/UVIS, and performs a near 1/2 box subpixel sampling of the WFC3/UVIS chips; followed by a dither pattern that performs a 1/3 & 2/3 diagonal subpixel sampling of the WFC3/UVIS chip, covers the chip gaps of WFC3/UVIS and ACS/WFC, and is a near 1/3 & 2/3 diagonal subpixel sampling of the AFC/WFC chip. For the F606W orbits the dither pattern is designed to perform 1/3 & 2/3 ACS/WFC diagonal subpixel sampling, cover the chip gaps of ACS/WFC and WFC3/UVIS chips, and near 1/3 & 2/3 WFC3/UVIS diagonal subpixel sampling. Due to the orientation constraints we have designed this observation to be done in two visits (one per target). 12 false 0.0 0.0 false false false false false false SUPPORTED CLUSTER OF GALAXIES GRAVITATIONAL LENS HIGH REDSHIFT CLUSTER This pointing is centered on the location of the western subcluster of DLSCL J0916+2953. J2000 09 16 15.0000 +29 51 0.00 J2000 CLUSTER OF GALAXIES GRAVITATIONAL LENS HIGH REDSHIFT CLUSTER This pointing is centered on the location of the southern subcluster of DLSCL J0916+2953. J2000 09 16 15.0000 +29 51 0.00 J2000 ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F814W ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F814W POS-TARG DITHER 5.943 This is the first dither pattern for the F814W exposures. It is an ACS/WFC box dither pattern that performs a 1/2 subpixel sampling, covers the chip gaps of ACS/WFC and WFC3/UVIS, and is performs a near 1/2 box subpixel sampling of the WFC3/UVIS chips. LINE 3.077 false false 166.993 4 91.429 ACS-WFC-DITHER-BOX 1 false POS-TARG DITHER 2.746 This is meant to be the second dither pattern for the F814W set of exposures. It is a 1/3 & 2/3 diagonal subpixel sampling of the WFC3/UVIS chip, covers the chip gaps of WFC3/UVIS and ACS/WFC, and is a near 1/3 & 2/3 diagonal subpixel sampling of the AFC/WFC chip. This dither pattern is designed to be complementary to pattern 1 which is an ACS/WFC box and approximatly WFC/UVIS box pattern. LINE false false 2 277.936 ACS-WFC-DITHER-LINE 2 false POS-TARG DITHER 2.746 This is the dither pattern for the F606W orbits and is designed to perform 1/3 & 2/3 ACS/WFC diagonal subpixel sampling, cover the chip gaps of ACS/WFC and WFC3/UVIS chips, and near 1/3 & 2/3 WFC3/UVIS diagonal subpixel sampling. LINE false false 3 103.052 ACS-WFC-DITHER-LINE 3 false The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. ACS/WFC & WFC3/UVIS parallel observations of DLSCL J0916+2953-West subcluster. The orient constraints are required to place the WFC3 FOV as close to the East subcluster as possible. (Tic-Visit :proposal-id 12377 :visit-id "01" :proposal-version -1 :trans-version "20100505" :date "27-Sep-2010 11:52:43.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 5156768 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12377 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12377 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2923 :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 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12377 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3035 :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 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12377 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) true 3 0 The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. ACS/WFC & WFC3/UVIS parallel observations of DLSCL J0916+2953-South subcluster. The orient constraints are required to place the WFC3 FOV as close to the East subcluster as possible. (Tic-Visit :proposal-id 12377 :visit-id "02" :proposal-version -1 :trans-version "20100505" :date "27-Sep-2010 11:53:00.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 5156768 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12377 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12377 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2923 :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 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12377 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3035 :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 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12377 :visit-id "02" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) true 3 0