12368( 3) - 15-Mar-2011 10:25:45 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12368 Version: 3 Check-in Time: 15-Mar-2011 10:25:45 STScI Edit Number: 0 Title Extreme Mergers from the Massive Cluster Survey ------------------------------------------------------------------------------------ Type Cycle GO 18 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Roger G. Morris Stanford University CoI: Prof. Steven W. Allen Stanford University N CoI: Dr. Anja von der Linden Stanford University N CoI: Dr. Harald Ebeling University of Hawaii N ------------------------------------------------------------------------------------ Abstract We will observe an extraordinary, high-redshift galaxy cluster from the Massive Cluster Survey. The target is a very rare, triple merger system, and likely lies at the one of deepest nodes of the cosmic web. The target shows multiple strong gravitational lensing arcs in the cluster core. This target only possesses a very short (10ks) Chandra observations, and is unobserved by XMM-Newton. The X-ray data from this joint Chandra/HST proposal will be used to probe the mass distribution of hot, baryonic gas, and to reveal the details of the merger physics and the process of cluster assembly. We will also search for hints of X-ray emission from filaments between the merging clumps. Subaru and some Hubble Space Telescope imaging data are in hand; we will gather additional HST coverage for a lensing analysis. ------------------------------------------------------------------------------------ Observations Description ------------------------ The galaxy cluster MACS J1226 consists of three merging sub-clumps. The two main clumps (NE and S) each possess strong gravitational lensing arcs. We will observe these two main clumps with two separate pointings. Our aim is a combined strong and weak gravitational lensing analysis. The prime instrument will be ACS, with WFC3 operating in coordinated parallel mode for increased spatial coverage of this significantly extended galaxy cluster. Each pointing will consist of two orbits, one in F606W and one in F814W. The LOW SKY condition is required to allow a weak lensing analysis (this needs accurate shape measurements of faint background galaxies and hence the lowest possible instrumental background). The time required to dump the ACS and WFC3 buffers makes it impossible to obtain more than three equal length exposures in any one orbit. Since we prefer to use more than 3 dither positions for effective removal of cosmic rays etc, the exposures are of non-equal length so that it is possible to fit 4 of them into each orbit. Real Time Justification ----------------------- Calibration Justification 12368( 3) - 15-Mar-2011 10:25:45 - [ 2] ------------------------- Additional Comments ------------------- There are fairly bright stars at i) 12 26 46.17, +21 48 50.57; and ii) 12 26 38.81, +21 47 21.13. The latter is of unknown magnitude in BOT but is clearly visible as a bright object in our existing ground-based Subaru data. Depending on the roll angle with which the observations are performed, these stars could potentially impact the quality of science data from the ACS exposure of the S clump (star i) and both parallel WFC3 observations (star ii). It might therefore be advantageous to allow us to fine-tune the target positions (by of the order of 10 arc-seconds) and/or the precise roll angle once the observations are scheduled and the range of allowed roll angles is known. Because these sources are highly extended, there is quite a wide range of acceptable target positions. This flexibility would also allow us to position the apertures to cover the largest possible fraction of the region of interest. (The system is much larger than the ACS field of view, but the W direction, towards the third sub-clump, is likely the most interesting direction.) ------------------------------------------------------------------------------------ 12368( 3) - 15-Mar-2011 10:25:45 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 MACSJ1226.8+ CLUSTER OF GALAXIES, RA=12H26M51.6500S +/- 0.1", J2000 Z = V = 16 +/- 1 2153-NE GRAVITATIONAL LENS, DEC=+21D52'25.00" +/- 0.1" 0.437 HIGH REDSHIFT CLUSTER Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 2 MACSJ1226.8+ CLUSTER OF GALAXIES, RA=12H26M51.1600S +/- 0.1", J2000 Z = V = 16 +/- 1 2153-S GRAVITATIONAL LENS, DEC=+21D49'52.50" +/- 0.1" 0.437 HIGH REDSHIFT CLUSTER Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 12368( 3) - 15-Mar-2011 10:25:45 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 3.011 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 85.28 Angle_Between_Sides Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ 12368( 3) - 15-Mar-2011 10:25:45 - [ 5] Visit: 01 Visit Requirements: ORIENT 148D TO 154 D 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 MACSJ1226.8 ACS/WFC ACCUM WFC1-FIX F606W CR-SPLIT=NO 1 650 S POS TARG 17, 0; LOW-SKY; +2153-NE see below PATTERN 1 1-2; PAR 2 WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY WFC3/UVI ACCUM UVIS F606W CR-SPLIT=NO 1 700 S S see below ------------------------------------------------------------------------------------------------------------------------------------ 3 MACSJ1226.8 ACS/WFC ACCUM WFC1-FIX F814W CR-SPLIT=NO 1 650 S POS TARG 17, 0; LOW-SKY; +2153-NE see below PATTERN 1 3-4; PAR 4 WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO 1 700 S S see below ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ MACSJ1226.8+2153-NE 1 ACS/WFC ACCUM WFC1-FIX F606W 1 none none none 1 370.0 S MACSJ1226.8+2153-NE 1 ACS/WFC ACCUM WFC1-FIX F606W 2 none none none 1 N/A MACSJ1226.8+2153-NE 1 ACS/WFC ACCUM WFC1-FIX F606W 3 none none none 1 N/A MACSJ1226.8+2153-NE 1 ACS/WFC ACCUM WFC1-FIX F606W 4 none none none 1 370.0 S ANY 2 WFC3/UVI ACCUM UVIS F606W 1 none none none 1 465.0 S S ANY 2 WFC3/UVI ACCUM UVIS F606W 2 none none none 1 N/A S ANY 2 WFC3/UVI ACCUM UVIS F606W 3 none none none 1 N/A S ANY 2 WFC3/UVI ACCUM UVIS F606W 4 none none none 1 465.0 S S MACSJ1226.8+2153-NE 3 ACS/WFC ACCUM WFC1-FIX F814W 1 none none none 2 370.0 S MACSJ1226.8+2153-NE 3 ACS/WFC ACCUM WFC1-FIX F814W 2 none none none 2 N/A MACSJ1226.8+2153-NE 3 ACS/WFC ACCUM WFC1-FIX F814W 3 none none none 2 N/A MACSJ1226.8+2153-NE 3 ACS/WFC ACCUM WFC1-FIX F814W 4 none none none 2 370.0 S ANY 4 WFC3/UVI ACCUM UVIS F814W 1 none none none 2 465.0 S S ANY 4 WFC3/UVI ACCUM UVIS F814W 2 none none none 2 N/A S ANY 4 WFC3/UVI ACCUM UVIS F814W 3 none none none 2 N/A S 12368( 3) - 15-Mar-2011 10:25:45 - [ 6] 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 | ------------------------------------------------------------------------------------------------------------------------------------ ANY 4 WFC3/UVI ACCUM UVIS F814W 4 none none none 2 465.0 S S 12368( 3) - 15-Mar-2011 10:25:45 - [ 7] Visit: 02 Visit Requirements: ORIENT 148D TO 154 D 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 MACSJ1226.8 ACS/WFC ACCUM WFC1-FIX F606W CR-SPLIT=NO 1 650 S POS TARG -11, 1; +2153-S see below LOW-SKY; PATTERN 1 1-2; PAR 2 WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY WFC3/UVI ACCUM UVIS F606W CR-SPLIT=NO 1 700 S S see below ------------------------------------------------------------------------------------------------------------------------------------ 3 MACSJ1226.8 ACS/WFC ACCUM WFC1-FIX F814W CR-SPLIT=NO 1 650 S POS TARG -11, 1; +2153-S see below LOW-SKY; PATTERN 1 3-4; PAR 4 WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO 1 700 S S see below ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ MACSJ1226.8+2153-S 1 ACS/WFC ACCUM WFC1-FIX F606W 1 none none none 1 370.0 S MACSJ1226.8+2153-S 1 ACS/WFC ACCUM WFC1-FIX F606W 2 none none none 1 N/A MACSJ1226.8+2153-S 1 ACS/WFC ACCUM WFC1-FIX F606W 3 none none none 1 N/A MACSJ1226.8+2153-S 1 ACS/WFC ACCUM WFC1-FIX F606W 4 none none none 1 370.0 S ANY 2 WFC3/UVI ACCUM UVIS F606W 1 none none none 1 465.0 S S ANY 2 WFC3/UVI ACCUM UVIS F606W 2 none none none 1 N/A S ANY 2 WFC3/UVI ACCUM UVIS F606W 3 none none none 1 N/A S ANY 2 WFC3/UVI ACCUM UVIS F606W 4 none none none 1 465.0 S S MACSJ1226.8+2153-S 3 ACS/WFC ACCUM WFC1-FIX F814W 1 none none none 2 370.0 S MACSJ1226.8+2153-S 3 ACS/WFC ACCUM WFC1-FIX F814W 2 none none none 2 N/A MACSJ1226.8+2153-S 3 ACS/WFC ACCUM WFC1-FIX F814W 3 none none none 2 N/A MACSJ1226.8+2153-S 3 ACS/WFC ACCUM WFC1-FIX F814W 4 none none none 2 370.0 S ANY 4 WFC3/UVI ACCUM UVIS F814W 1 none none none 2 465.0 S S ANY 4 WFC3/UVI ACCUM UVIS F814W 2 none none none 2 N/A S ANY 4 WFC3/UVI ACCUM UVIS F814W 3 none none none 2 N/A S 12368( 3) - 15-Mar-2011 10:25:45 - [ 8] 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 | ------------------------------------------------------------------------------------------------------------------------------------ ANY 4 WFC3/UVI ACCUM UVIS F814W 4 none none none 2 465.0 S S 12368( 3) - 15-Mar-2011 10:25:45 - [ 9] Summary Form for Proposal 12368 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS, WFC1-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements LOW-SKY, ORIENT 148D TO 154 D, PAR 2 WITH 1, PAR 4 WITH 3, PATTERN 1 1-2, PATTERN 1 3-4, POS TARG -11, 1, POS TARG 17, 0 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names ANY, MACSJ1226.8+2153-NE, MACSJ1226.8+2153-S ------------------------------------------------------------------------------------------------------------------------------------