18191( 2) - 29-Sep-2025 18:54:09 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 18191 Version: 2 Check-in Time: 29-Sep-2025 18:54:09 STScI Edit Number: 0 Title Multiwavelength Observations of the Highest-Redshift Dynamically Relaxed Galaxy Cluster ------------------------------------------------------------------------------------ Type Cycle GO 33 ------------------------------------------------------------------------------------ Investigators Contact? PI: Anthony M Flores Rutgers University Y CoI: Prof. Steven W. Allen Stanford University N CoI: Dr. Adam Mantz Stanford University N CoI: Dr. R. Glenn Morris Stanford University N CoI: Prof. Michael A. McDonald Massachusetts Institute of Technology N CoI: Dr. Taweewat Somboonpanyakul Chulalongkorn University N CoI: Haley Rose Stueber Stanford University N CoI: Abby Y Pan Stanford University N ------------------------------------------------------------------------------------ Abstract We propose joint Chandra, XMM-Newton, and HST observations of ACT-CL J0123.5-0428, a z=1.5 galaxy cluster newly identified as the highest redshift relaxed cool-core cluster known. Deeper X-ray observations from Chandra and XMM, paired with wideband WFC3/IR imaging from Hubble, will allow us to exquisitely characterize the (thermo)dynamics and chemistry of the ICM out to large radius - including a precise gas mass profile for cosmological studies - and constrain the morphologies and stellar histories of member galaxies over the same spatial scale. In combination, these observations will provide a greatly enhanced picture of feedback processes in the early Universe and significantly extend the redshift range probed by studies of ICM/galaxy evolution and cosmology in relaxed systems. ------------------------------------------------------------------------------------ Observations Description ------------------------ This program consists of 10 total HST orbits using the WFC3 to observe a high redshift (z=1.5) galaxy cluster. This system will be observed for 5 total orbits using the F105W IR filter, and 5 total orbits using the F140W IR filter. This program contains 5 visits to the object. Each visit will consist of 2 orbits, with one orbit corresponding to each of the above filters. For each visit, the center of the cluster (roughly the position of the BCG) will be used as the coordinates of the target. ------------------------------------------------------------------------------------ 18191( 2) - 29-Sep-2025 18:54:09 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 ACT-CLJ0123. CLUSTER OF GALAXIES, RA=01H23M32.0956S, J2000 Z = 1.5 21 (z band), 18.5 (CATWISE W1) 5-0428 HIGH REDSHIFT CLUSTER DEC=-04D28'26.22" Reference Frame: ICRS Extended: YES Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 18191( 2) - 29-Sep-2025 18:54:09 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 1.716 Line_Spacing 1.095 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 18191( 2) - 29-Sep-2025 18:54:09 - [ 4] Visit: 01 (First visit) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 ACT-CLJ0123 WFC3/IR MULTIAC IR F105W NSAMP=12, SAMP-SEQ=SPARS25 2 DEF PATTERN 1 1 .5-0428 CUM (2223.504 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ACT-CLJ0123 WFC3/IR MULTIAC IR F140W NSAMP=12, SAMP-SEQ=SPARS25 2 DEF PATTERN 1 2 .5-0428 CUM (2223.504 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 1 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 1 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 2 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 2 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 3 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 3 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 4 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 4 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 1 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 1 none 2 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 2 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 2 none 2 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 3 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 3 none 2 none 2 N/A CUM 18191( 2) - 29-Sep-2025 18:54:09 - [ 5] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 4 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 4 none 2 none 2 N/A CUM 18191( 2) - 29-Sep-2025 18:54:09 - [ 6] Visit: 02 (Second visit) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 ACT-CLJ0123 WFC3/IR MULTIAC IR F105W NSAMP=12, SAMP-SEQ=SPARS25 2 DEF PATTERN 1 1 .5-0428 CUM (2223.504 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ACT-CLJ0123 WFC3/IR MULTIAC IR F140W NSAMP=12, SAMP-SEQ=SPARS25 2 DEF PATTERN 1 2 .5-0428 CUM (2223.504 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 1 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 1 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 2 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 2 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 3 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 3 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 4 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 4 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 1 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 1 none 2 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 2 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 2 none 2 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 3 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 3 none 2 none 2 N/A CUM 18191( 2) - 29-Sep-2025 18:54:09 - [ 7] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 4 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 4 none 2 none 2 N/A CUM 18191( 2) - 29-Sep-2025 18:54:09 - [ 8] Visit: 03 (Third visit) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 ACT-CLJ0123 WFC3/IR MULTIAC IR F105W NSAMP=12, SAMP-SEQ=SPARS25 2 DEF PATTERN 1 1 .5-0428 CUM (2223.504 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ACT-CLJ0123 WFC3/IR MULTIAC IR F140W NSAMP=12, SAMP-SEQ=SPARS25 2 DEF PATTERN 1 2 .5-0428 CUM (2223.504 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 1 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 1 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 2 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 2 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 3 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 3 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 4 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 4 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 1 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 1 none 2 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 2 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 2 none 2 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 3 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 3 none 2 none 2 N/A CUM 18191( 2) - 29-Sep-2025 18:54:09 - [ 9] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 4 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 4 none 2 none 2 N/A CUM 18191( 2) - 29-Sep-2025 18:54:09 - [ 10] Visit: 04 (Fourth visit) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 ACT-CLJ0123 WFC3/IR MULTIAC IR F105W NSAMP=12, SAMP-SEQ=SPARS25 2 DEF PATTERN 1 1 .5-0428 CUM (2223.504 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ACT-CLJ0123 WFC3/IR MULTIAC IR F140W NSAMP=12, SAMP-SEQ=SPARS25 2 DEF PATTERN 1 2 .5-0428 CUM (2223.504 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 1 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 1 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 2 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 2 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 3 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 3 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 4 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 4 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 1 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 1 none 2 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 2 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 2 none 2 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 3 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 3 none 2 none 2 N/A CUM 18191( 2) - 29-Sep-2025 18:54:09 - [ 11] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 4 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 4 none 2 none 2 N/A CUM 18191( 2) - 29-Sep-2025 18:54:09 - [ 12] Visit: 05 (Fifth visit) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 ACT-CLJ0123 WFC3/IR MULTIAC IR F105W NSAMP=12, SAMP-SEQ=SPARS25 2 DEF PATTERN 1 1 .5-0428 CUM (2223.504 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ACT-CLJ0123 WFC3/IR MULTIAC IR F140W NSAMP=12, SAMP-SEQ=SPARS25 2 DEF PATTERN 1 2 .5-0428 CUM (2223.504 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 1 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 1 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 2 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 2 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 3 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 3 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 4 none 1 none 1 N/A CUM ACT-CLJ0123.5-0428 1 WFC3/IR MULTIAC IR F105W 4 none 2 none 1 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 1 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 1 none 2 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 2 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 2 none 2 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 3 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 3 none 2 none 2 N/A CUM 18191( 2) - 29-Sep-2025 18:54:09 - [ 13] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 4 none 1 none 2 N/A CUM ACT-CLJ0123.5-0428 2 WFC3/IR MULTIAC IR F140W 4 none 2 none 2 N/A CUM 18191( 2) - 29-Sep-2025 18:54:09 - [ 14] Summary Form for Proposal 18191 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=12, SAMP-SEQ=SPARS25 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F105W, F140W ------------------------------------------------------------------------------------------------------------------------------------ Target Names ACT-CLJ0123.5-0428 ------------------------------------------------------------------------------------------------------------------------------------