5987( 8) - 03/06/96 15:25 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5987 Version: 8 Check-in Date: 06-Mar-1996 15:19:18 1.Proposal Title: WFPC Observations of Distant, X-ray Luminous Clusters of Galaxies ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Galaxies & Clusters GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Megan Donahue Space Telescope Science Institute CoI: John T. Stocke University of Colorado N CoI: Isabella M. Gioia Institute for Astronomy, Hawaii N CoI: Gerry A. Luppino Institute for Astronomy, Hawaii N ------------------------------------------------------------------------------------ 6. Abstract Recent HST WFPC images of distant clusters of galaxies have been spectacular, revealing surprisingly complex galaxy morphologies and a much higher interaction and merger rate compared to present-day clusters. Because these images are exclusively of optically-selected clusters, our view of the z ~ 0.5 Universe may be somewhat biased due to the method of cluster selection. We therefore propose to obtain deep images of three equally distant (z=0.55-0.83) X-ray -selected, X-ray-luminous clusters of galaxies to study their galaxy morphologies and merger/interaction rates. We will compare these clusters with low-z clusters of similar X-ray luminosity and with the distant clusters that HST has already observed. Because our 3 targets are >~ 5 times more luminous in X-rays and have much denser intracluster gas than the optically-selected clusters already observed, they are directly comparable to nearby clusters with well-developed intracluster media (ICM). Since ICM evolution plays at least a partial role many models of galaxy evolution, these observations will test those models. Our supplementary ground- based and satellite (ROSAT and ASCA) observations will supply galaxy colors, spectra, velocity dispersions, gas morphology, gas temperatures and metallicities, as well as gas and cluster masses to compare to the HST imaging data. ------------------------------------------------------------------------------------ 5987( 8) - 03/06/96 15:25 - [ 2] Observations Description ------------------------ We will construct a single image of each cluster, at rest- wavelength B. (Moving the rest wavelength to U would substantially reduce the number of galaxies that we will detect, since z=0.8 galaxies are very red in the observers frame.) Minimum time calculations were done for a minimum magnitude of m(B_rest)=25 mag arcsec^-2 and minimum S/N=10 in 1 arcsec^2. This will produce observations similar to those acquired by Dressler et al. with the WFPC2. We used values for sky and color corrections from the WFPC2 instrument handbook, as well as the integral for the individual filters. Sky noise exceeds read noise in exposures far exceeding 10 minutes. Therefore each exposure is the maximum allowed exposure in a given orbit, so that sky background is the most important source of noise. Cluster z BCG r_mag Filter Orbits Exp time MS0451-03 0.55 20.055 F702W 4 10,100 S MS1054-03 0.83 20.710 F814W 6 15,300 S MS1137+66 0.78 21.312 F814W 6 15,600 S The two more distant clusters require about 20% more time for similar limiting magnitude. Each orbit will produce a single image, each can be coadded for each source to remove cosmic ray events. The pointings will be moved an integral number of pixels to facilitate hot pixel and CR removal, and 1/2 integral number of pixels to improve resolution. Real Time Justification ----------------------- CVZ observations of MS1137+66 are possible, however scattered light in the red filter may prevent effective use of CVZ time. We had originally thought that we could use CVZ time, and our time request reflects that. But experienced WFPC personnel have informed us that at least 50% of CVZ would be unusable for red observations because of scattered light, so we would like to request an additional 3 orbits to complete our dataset, or alternatively, restrict observations to times of low-background. MODIFICATION: 3 orbits have been added from the Cycle 6 allocation. No CVZ constraints on this proposal. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address*3700 San Martin Drive ,*Baltimore, MD 21218 Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5987( 8) - 03/06/96 15:25 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 MS0451-03 CLUSTER OF GALAXIES, RA=04H 51M 40.5S,DEC=-03D 05' 1950 Z = 0.55 SURF(R) = 25 High Redshift Cluster 46",REGION,R=1.5' (z>0.5) Comments: Please check that the negative declination is converted properly for telescope pointing. If scattered light can be minimized by starting or ending observations at slightly different times, please do it. 2 MS1054-03 CLUSTER OF GALAXIES, RA=10H 54M 26.9S,DEC=-03D 21' 1950 Z=0.83 SURF(I) = 25 High Redshift Cluster 25.3",REGION,R=1' (z>0.5) Comments: Please check that the negative declination is converted properly for telescope pointing. If scattered light can be minimized by starting or ending observations at slightly different times, please do it, observe during low-background times. 3 MS1137+66 CLUSTER OF GALAXIES, RA=11H 37M 36.2S,DEC=66D 24' 1950 Z=0.78 SURF(I) = 25 High Redshift Cluster 56.9",REGION,R=1' (z>0.5) Comments: If scattered light can be minimized by starting or ending observations at slightly different times, please do it. 5987( 8) - 03/06/96 15:25 - [ 4] Visit: 01 Visit Requirements: ORIENT 315D TO 360D On Hold Comments: Additional Comments: Most of the galaxies with known redshifts are in the SE quadrant with respect to the nominal cD position. By centering the cD galaxy in WF4 and constraining the orientation angle of WF3 to be either directly East or SE of the center of WF4, we get most of the galaxies in one field of view. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 MS0451-03 WFPC2 IMAGE WF4 F702W CR-SPLIT=NO 1 2600S ------------------------------------------------------------------------------------------------------------------------------------ 2 MS0451-03 WFPC2 IMAGE WF4 F702W CR-SPLIT=NO 1 2600S POS TARG 0.50,0.50 ------------------------------------------------------------------------------------------------------------------------------------ 3 MS0451-03 WFPC2 IMAGE WF4 F702W CR-SPLIT=NO 1 2600S POS TARG .25,-.25 ------------------------------------------------------------------------------------------------------------------------------------ 4 MS0451-03 WFPC2 IMAGE WF4 F702W CR-SPLIT=NO 1 2600S POS TARG 0.50,-0.50 ------------------------------------------------------------------------------------------------------------------------------------ 5987( 8) - 03/06/96 15:25 - [ 5] Visit: 02 Visit Requirements: ORIENT 325D TO 35D On Hold Comments: Additional Comments: The galaxies in this cluster are aligned East to West, a strip about 2 arcminutes across. The optimal orientation may be to put the cD galaxy near the intersection of WF3 and WF4 at a U3 orientation of 315D, or near the intersection of WF2 and WF3 with a U3 orientation of 45E, but I worried about the possibility of the cD galaxy falling on the exact intersection. So I hedged my bet by centering the cD in WF3 and allowing the position angle of U3 to vary between +/-35D of North. A 180D change in orientation is allowed here. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 MS1054-03 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 2600S ------------------------------------------------------------------------------------------------------------------------------------ 2 MS1054-03 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 2600S POS TARG 0.50,-0.50 ------------------------------------------------------------------------------------------------------------------------------------ 3 MS1054-03 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 2600S POS TARG 0.50,0.50 ------------------------------------------------------------------------------------------------------------------------------------ 4 MS1054-03 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 2600S POS TARG -.25,.25 ------------------------------------------------------------------------------------------------------------------------------------ 5 MS1054-03 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 2600S POS TARG -0.50,-0.50 ------------------------------------------------------------------------------------------------------------------------------------ 6 MS1054-03 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 2600S POS TARG -0.50,0.50 ------------------------------------------------------------------------------------------------------------------------------------ 5987( 8) - 03/06/96 15:25 - [ 6] Visit: 03 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 MS1137+66 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 2400S LOW-SKY ------------------------------------------------------------------------------------------------------------------------------------ 2 MS1137+66 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 2400S LOW-SKY ------------------------------------------------------------------------------------------------------------------------------------ 3 MS1137+66 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 2400S LOW-SKY ------------------------------------------------------------------------------------------------------------------------------------ 4 MS1137+66 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 2400S POS TARG -.25,.25 LOW-SKY ------------------------------------------------------------------------------------------------------------------------------------ 5 MS1137+66 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 2400S LOW-SKY ------------------------------------------------------------------------------------------------------------------------------------ 6 MS1137+66 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 2400S LOW-SKY ------------------------------------------------------------------------------------------------------------------------------------ 5987( 8) - 03/06/96 15:25 - [ 7] Summary Form for Proposal 5987 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Galaxies & Clusters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 315D TO 360D POS TARG 0.50,0.50 POS TARG .25,-.25 POS TARG 0.50,-0.50 ORIENT 325D TO 35D POS TARG -.25,.25 POS TARG -0.50,-0.50 POS TARG -0.50,0.50 LOW-SKY POS TARG -.25,.25 LOW-SKY ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F702W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names MS0451-03 MS1054-03 MS1137+66 ------------------------------------------------------------------------------------------------------------------------------------