5967( 21) - 04/25/97 18:17 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5967 Version: 21 Check-in Date: 25-Apr-1997 17:29:10 1.Proposal Title: Imaging Clusters of Galaxies at z > 1 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Galaxies & Clusters GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Mark Dickinson SPACE TELESCOPE SCIENCE INSTITUTE CoI: Hyron Spinrad Department of Astronomy,University of N California, Berkeley CoI: S. George Djorgovski California Institute of Technology N CoI: Peter Eisenhardt Jet Propulsion Laboratory N CoI: S. Adam Stanford Infrared Processing and Analysis N Center/Jet Propulsion Laboratory ------------------------------------------------------------------------------------ 6. Abstract One of the most dramatic achievements of the refurbished HST is its capability for resolving the morphologies of galaxies at high redshift. In Cycle 4, we have obtained an extremely deep image of a rich cluster of galaxies at z=1.206 which surrounds the radio galaxy 3C 324. This observation offers a wealth of morphological data on ``normal'' galaxies at z > 1, many of which appear to be far from normal, at least by z=0 standards. At the same time, despite the early cosmic epoch (30\ is a population of apparently ordinary elliptical galaxies already in place, with colors and morphologies very similar to those of their z=0 counterparts. A substantial fraction of early--type cluster galaxies have existed throughout most of a Hubble Time, apparently unaffected by the processes which are driving strong evolution in the population of disk galaxies. We propose to continue this program, imaging two clusters at z=1.140 and 1.169 which span the range of high-z cluster properties. One cluster contains the numerous red galaxies also found around 3C 324, while the other appears to be dominated by blue, presumably star forming galaxies. In addition to extending our knowledge of ``ordinary'' galaxies at z > 1, these observations will provide high--quality data on the remarkably convoluted morphologies exhibited by the radio galaxies themselves at these redshifts. ------------------------------------------------------------------------------------ 5967( 21) - 04/25/97 18:17 - [ 2] Observations Description ------------------------ The observations we propose for Cycle 5 closely follow the approach we used in Cycle 4 for the 3C 324 cluster. The extremely long integration time (32 orbits) used for our observation of the 3C 324 cluster was motivated in part by our intent to unambiguously determine the nature of the ultra--red galaxies and compare them to present--day ellipticals. The combination of the very large k-- correction for these galaxies and the strong cosmological surface brightness dimming ((1+z)^4 = 23.7 at z=1.2) necessitated the long integration time granted in Cycle 4. We consider this experiment a success, as Fig. 3 demonstrates. Having established this to our satisfaction, for Cycle 5 we choose to reduce our exposure times and to increase our sample size to include two new clusters. Our goal is to conduct as broad a survey of cluster properties at z ~gt 1 as possible. If galaxy and cluster evolution is not precisely synchronized throughout the universe, then differences between clusters should be accentuated at higher and higher redshifts, as small differences in age become larger and larger fractions of the age of the universe. Already this appears to be the case at z ~ 0.5, where ``red'' clusters like 0016+16 coexist with ``blue'' clusters like 0939+47. We have examined subsets of our data on 3C 324, reducing the signal to noise to that equivalent to a 10--orbit exposure through F814W. We conclude that these integrations are sufficient for determining basic morphologies for cluster galaxies down to at least R=25.5. Real Time Justification ----------------------- None. Deep, ground--based optical and infrared imaging data are already in hand for our fields, and led to their selection as targets. As mentioned above, we have observed 3C 210 and 3C 324 with Rosat although only the latter was significantly detected. The most vital supporting data for this program is spectroscopy of the cluster galaxies in order to confirm their membership, determine their integrated spectral properties, and (if possible) measure cluster velocity dispersions. These clusters may represent the limit out to which this is possible with current telescopes and instrumentation: beyond z=1.2, the standard features used for redshift determination (e.g. OII, Ca H+K, the 4000Angstrom\\\\\\\\ break) move too far into the red where atmospheric emission bands are extremely strong, and LyAlpha (visible from the ground for z ~gt 1.6) is easily quenched by small amounts of dust in galaxies. Even at z=1.2, spectroscopy of these R ~ 25 galaxies provides a tremendous challenge. We plan to carry out a systematic program of multi--slit spectroscopy using the Keck 10m Telescope, to which two of the co-investigators (Spinrad and Djorgovski) have access. The multi--slit capabilities of the Keck LRIS spectrograph have only recently become functional, and no such observations were possible for the 3C 324 cluster during the spring 1994 observing season. A short (1 hour) single--slit observation of one of the ultra-- red galaxies in that field showed a spectrum consistent with that of a z=1.2 elliptical, but with insufficient signal--to- -noise to secure the redshift unambiguously. That observation is encouraging, however, and we believe that longer integrations in multi--object mode during the coming year will be capable of obtaining many redshifts within these clusters. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 5967( 21) - 04/25/97 18:17 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: ------------------------------------------------------------------------------------ 5967( 21) - 04/25/97 18:17 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 3C210 GALAXY,RADIO RA=8H 58M 10.58S +/- 1S,DEC=27D J2000 Z = R = 22 GALAXY,HIGH Z 50' 30.0" +/- 1" 1.169 GAL,BCM,CLUSTER OF GALAXIES,HIGH REDSHIFT Comments: Target position is not for radio galaxy, but is a WF2- FIX center position designed to place radio galaxy + cluster in desired location on WFPC2. 2 3C267 CLUSTER OF RA=11H 49M 55.73S +/- 1S,DEC=12D 2000 z=1.140 R = 22 GALAXIES,HIGH REDSHIFT 46' 49.2" +/- 1" CLUSTER,RICH CLUSTER,GALAXY,RADIO Comments: Target position is not for radio galaxy, but is a WF2- FIX center position designed to place radio galaxy + cluster in desired location on WFPC2. 5967( 21) - 04/25/97 18:17 - [ 5] Visit: 01 Visit Requirements: GROUP 1-2 WITHIN 7D ORIENT 99D TO 102D BEFORE 19-MAY-1996 On Hold Comments: Additional Comments: BEFORE 19-MAY-1996 special requirement included to avoid bright background (zodiacal + possible scattered light). Please schedule as early as possible -- zodiacal background increases rapidly with time. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 3C210 WFPC2 IMAGE WF2-FIX F814W CR-SPLIT=NO 5 2100 S EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 5967( 21) - 04/25/97 18:17 - [ 6] Visit: 02 Visit Requirements: SAME ORIENT AS 01 GROUP 1-2 WITHIN 7D BEFORE 19-MAY-1996 On Hold Comments: Additional Comments: BEFORE 19-MAY-1996 special requirement included to avoid bright background (zodiacal + possible scattered light). Please schedule as early as possible -- zodiacal background increases rapidly with time. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 2 3C210 WFPC2 IMAGE WF2-FIX F814W CR-SPLIT=NO 5 2100 S EXPAND POS TARG -0.95, -0.95 ------------------------------------------------------------------------------------------------------------------------------------ 5967( 21) - 04/25/97 18:17 - [ 7] Visit: 03 Visit Requirements: GROUP 3-4 WITHIN 14 D ORIENT 134.5D TO 135.5D On Hold Comments: Additional Comments: Please schedule as early as possible -- zodiacal background increases rapidly with time. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 3C267 WFPC2 IMAGE WF2-FIX F814W CR-SPLIT=NO 3 2100 S EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 2 3C267 WFPC2 IMAGE WF2-FIX F814W CR-SPLIT=NO 2 2100 S POS TARG -0.50,0.25 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 5967( 21) - 04/25/97 18:17 - [ 8] Visit: 04 Visit Requirements: GROUP 3-4 WITHIN 14 D SAME ORIENT AS 03 On Hold Comments: Additional Comments: Please schedule as early as possible -- zodiacal background increases rapidly with time. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 3C267 WFPC2 IMAGE WFALL F814W CR-SPLIT=NO 3 2100 S POS TARG -0.75,0.75 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 2 3C267 WFPC2 IMAGE WFALL F814W CR-SPLIT=NO 2 2100 S POS TARG -0.25,0.50 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 5967( 21) - 04/25/97 18:17 - [ 9] Summary Form for Proposal 5967 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Galaxies & Clusters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GROUP 1-2 WITHIN 7D ORIENT 99D TO 102D BEFORE 19-MAY-1996 EXPAND SAME ORIENT AS 01 GROUP 1-2 WITHIN 7D BEFORE 19-MAY-1996 EXPAND POS TARG -0.95,-0.95 GROUP 3-4 WITHIN 14 D ORIENT 134.5D TO 135.5D POS TARG -0.50,0.25 EXPAND GROUP 3-4 WITHIN 14 D SAME ORIENT AS 03 POS TARG -0.75,0.75 EXPAND POS TARG -0.25,0.50 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names 3C210 3C267 ------------------------------------------------------------------------------------------------------------------------------------