6000( 0) - 07/18/95 19:13 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6000 Version: ********** Check-in Date: ********** 1.Proposal Title: Morphology and Photometry of Galaxies in Optically Selected High Redshift Clusters ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Galaxies & Clusters GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Marc Postman Space Telescope Science Institute CoI: James E. Gunn Princeton University N CoI: John G. Hoessel University of Wisconsin N CoI: Lori Lubin Princeton University N CoI: J. Beverley Oke Dominion Astrophysical Observatory N CoI: Donald Schneider Penn State University N ------------------------------------------------------------------------------------ 6. Abstract We are requesting deep, broad-band red WFPC2 images of six distant clusters (0.6 < z < 1.2) to analyze the morphological characteristics of the cluster members. The high angular resolution imagery of HST, combined with our extensive ground based u,v,g,r,i,z photometry, will allow the measurement of the morphological fractions in distant clusters as functions of redshift, color, galaxy density, and global cluster properties such as core radius and ellipticity. We will also study the rest frame UV properties of the cluster galaxies as a function of morphological type. Utilizing extensive data for clusters at lower redshifts, we will place new and fundamental constraints on the evolution of structural parameters of cluster galaxies, on the origin of the morphological segregation of galaxies, and on galaxy and cluster formation. The cluster sample has been selected objectively from large area optical/near IR ground based surveys. The proposal team has committed a significant amount of time on ground based telescopes for on--going spectroscopic data acquisition that will compliment the HST observations. We have also developed and tested algorithms for performing objective measurements of galaxy morphology that will be applied to the data. ------------------------------------------------------------------------------------ 6000( 0) - 07/18/95 19:13 - [ 2] Observations Description ------------------------ The F702W filter is the most efficient choice for imaging z > 0.6 clusters given the typical spectral energy distribution of the cluster galaxies combined with the relatively high QE and broad bandpass of this filter. The sole exception is for cluster CL023143+004844 where we choose to observe with the F606W filter because this cluster contains bluer galaxies. We opt against using F814W because the sky background is slightly higher, the QE is slightly lower, and one does not gain a significant signal-to-noise ratio (S/N) improvement given a passively evolving elliptical spectral energy distribution (with significant color evolution or a high spiral fraction, the drive to observe much redward of 8000 Angstrom is negated). We will rely on our ground based data for integrated color information. Our exposure time estimates are based on a direct analysis of the WFPC2+F702W HST data of the z = 1.2 3C324 cluster observed by Dickinson (who kindly provided us access to these data). Our desire is to reach a S/N ratio of at least ~5 within the half-light radius of 0.50 L^* galaxies at z ~ 1.0. This requirement is based jointly on the desire to have quality data for a significant number of cluster members and on our estimates of the minimum signal needed to perform reliable measurement of basic morphological characteristics such as the effective radius, compactness parameter, asymmetry, and radial profile. After 16,800 seconds of exposure time, the relationship between S/N ratio and AB magnitude within the half-light radius of galaxies in the 3C324 WFC data is log_10(S/N) = -0.413 AB + 10.827. Thus, galaxies with AB <= 24.52 will typically have S/N >= 5 over their central 80 WFC pixels. This corresponds to the flux a passively evolving 0.50 L^* elliptical galaxy at z = 1.0 would have within its half-light radius (assuming an effective radius of 3h^-1 kpc). Color evolution aids S/N considerations but we want to be conservative to avoid biasing our results. We will, thus, require 7 orbits to perform our analysis on our most distant clusters; 6 orbits for the clusters at 0.7 <= z <= 0.83; and 7 orbits for CL023143+004844 because of its especially blue galaxy population. These S/N computations are relatively independent of the assumed Hubble constant. The individual exposures will be CR -split. We will request offsets of a few WFC-pixels after every 2 orbits to improve rejection of residual hot pixels and other CCD defects. Real Time Justification ----------------------- No special requirements needed. We have acquired and reduced multiband photometry for the clusters in our HST target list (see table). Spectroscopic observations for galaxies in 4 of our 6 cluster already exist and were obtained by us at the Hale 5m telescope. Lubin, Gunn, and Postman have a dedicated observing program with the Apache Point ARC 3.5m telescope to continue our spectroscopic observations. We have up to 20 hrs guaranteed time on the ARC 3.5m per month, beginning with 16 hrs in October 1994. Oke will have several nights on the Keck 10m telescope in the spring and fall of 1995 to carry out spectroscopic slit--mask observations of additional galaxies in these clusters. Schneider and Hoessel will also commit significant blocks of their GTO time on the Hobby-Eberly 8m telescope (formally the SST) and on the WIYN telescope, respectively, for spectroscopic data acquisition. All members of the proposal team have expertise in the fields of galaxy and cluster formation and evolution. Postman and Gunn have developed and tested software for measuring structural parameters and performing morphological classification of galaxies. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6000( 0) - 07/18/95 19:13 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6000( 0) - 07/18/95 19:13 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GAL-CLUS- CLUSTER OF GALAXIES, RA = 00H 23M 53.76S +/- 0.5S, J2000 Z = V = 23.7 002352+04230 RICH CLUSTER DEC = +04D 23' 11.1" +/- 2.0" 0.832 7 Comments: Gunn, Hoessel, Oke Cluster KP Chi Epsilon 2 GAL-CLUS- CLUSTER OF GALAXIES, RA = 02H 31M 43.82S +/- 0.5S, J2000 Z = V = 22.0 023143+00484 RICH CLUSTER DEC = +00D 48' 47.3" +/- 2.0" 0.607 4 Comments: Gunn, Hoessel, Oke Cluster KP Epsilon 3 GAL-CLUS- CLUSTER OF GALAXIES, RA = 16H 07M 31.63S +/- 0.5S, J2000 Z = V = 23.5 160733+41101 RICH CLUSTER DEC = +41D 10' 11.7" +/- 2.0" 0.900 3 Comments: Gunn, Hoessel, Oke Cluster C-37 = PDC Suppl. 19. 6000( 0) - 07/18/95 19:13 - [ 5] Visit: 01 Visit Requirements: ORIENT 315D TO 55D On Hold Comments: Additional Comments: Rotate U3 axis between 315D and 55D east of north Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 101 GAL-CLUS- WFPC2 IMAGE WFALL- F702W CR-SPLIT=NO 1 2300S POS TARG 10.00, 10.00 002352+0423 FIX 07 ------------------------------------------------------------------------------------------------------------------------------------ 102 GAL-CLUS- WFPC2 IMAGE WFALL- F702W CR-SPLIT=NO 3 2600S POS TARG 10.00, 10.00 002352+0423 FIX 07 ------------------------------------------------------------------------------------------------------------------------------------ 103 GAL-CLUS- WFPC2 IMAGE WFALL- F702W CR-SPLIT=NO 3 2600S POS TARG 10.50, 10.50 002352+0423 FIX 07 ------------------------------------------------------------------------------------------------------------------------------------ 6000( 0) - 07/18/95 19:13 - [ 6] Visit: 02 Visit Requirements: ORIENT 315D TO 75D On Hold Comments: Additional Comments: Rotate U3 axis between 315D and 75D east of north Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 201 GAL-CLUS- WFPC2 IMAGE WFALL- F606W CR-SPLIT=NO 1 2300S POS TARG 10.00, 10.00 023143+0048 FIX 44 ------------------------------------------------------------------------------------------------------------------------------------ 202 GAL-CLUS- WFPC2 IMAGE WFALL- F606W CR-SPLIT=NO 2 2600S POS TARG 10.00, 10.00 023143+0048 FIX 44 ------------------------------------------------------------------------------------------------------------------------------------ 203 GAL-CLUS- WFPC2 IMAGE WFALL- F606W CR-SPLIT=NO 3 2600S POS TARG 10.50, 10.50 023143+0048 FIX 44 ------------------------------------------------------------------------------------------------------------------------------------ 6000( 0) - 07/18/95 19:13 - [ 7] Visit: 03 Visit Requirements: ORIENT 115D TO 175D On Hold Comments: Additional Comments: Rotate U3 axis between 115D and 175D east of north Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 301 GAL-CLUS- WFPC2 IMAGE WFALL- F702W CR-SPLIT=NO 1 2400S POS TARG 10.00, 10.00 160733+4110 FIX 13 ------------------------------------------------------------------------------------------------------------------------------------ 302 GAL-CLUS- WFPC2 IMAGE WFALL- F702W CR-SPLIT=NO 3 2700S POS TARG 10.00, 10.00 160733+4110 FIX 13 ------------------------------------------------------------------------------------------------------------------------------------ 303 GAL-CLUS- WFPC2 IMAGE WFALL- F702W CR-SPLIT=NO 3 2700S POS TARG 10.50, 10.50 160733+4110 FIX 13 ------------------------------------------------------------------------------------------------------------------------------------ 6000( 0) - 07/18/95 19:13 - [ 8] Summary Form for Proposal 6000 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 55D POS TARG 10.00, 10.00 POS TARG 10.50, 10.50 ORIENT 315D TO 75D ORIENT 115D TO 175D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F702W F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names GAL-CLUS-002352+042307 GAL-CLUS-023143+004844 GAL-CLUS-160733+411013 ------------------------------------------------------------------------------------------------------------------------------------