! Proposal 6488, submission 1 ! PI: Ian Smail ! Received Fri Feb 2 06:48:48 EST 1996 ! From: Ian.Smail@durham.ac.uk ! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6488,v 3.1 1996/02/08 00:06:26 pepsa Exp $ ! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6488,v 3.1 1996/02/08 00:06:26 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Lucas ! Phone: 410-338-4716 , E-mail: lucas@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. ! Name of Phase I Proposal: archive-0270.smail.prop ! Date generated: Fri Dec 22 16:29:26 EST 1995 ! Proposal_Information ! Section 4 Title: AN ULTRA-FAINT GALAXY COUNT AND REDSHIFT SURVEY USING CLUSTER LENSES Proposal_Category: GO Scientific_Category: COSMOLOGY Cycle: 6 Investigators PI_name: Ian Smail PI_Institution: Department of Physics, University of Durham CoI_Name: Richard Ellis CoI_Institution: Institute of Astronomy Contact: Y ! Y or N (designate at most one contact) CoI_Name: Jean-Paul Kneib CoI_Institution: Institute of Astronomy Contact: N ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) The high surface density (~ 200 arcmin^-2) of the faintest sources revealed via ultra-deep CCD images suggests we may have detected a population of high redshift pre-galactic halos. The abundance, clustering and other properties of such sources would be valuable constraints on theories of structure formation. To verify the hypothesis redshifts and hence luminosities are required for sources well beyond the spectroscopic limits of even 10-m class telescopes. By using the gravitational distortion induced by foreground rich clusters, we demonstrate that it is possible to secure reliable distances at these limits by analysing the images of background sources viewed through a highly-constrained cluster lens. From HST images of a single cluster, the redshift distribution of ~ 60 objects to R=25 has already been determined. A further development is the use of lensing to provide constraints on source counts and redshifts to yet fainter limits, R~29, by analysing the location and abundance of highly-magnified `pairs'. The combination of both techniques, made possible only with HST, provides the only avenue towards constraining a pre-galactic halo population. We propose to apply both techniques to a further cluster enabling us to 1) compare our lensing-derived N(z) at R<=23 with spectroscopic results, 2) extend the inversion depth to R=26, and 3) analyse the frequency and geometry of faint pairs to constrain the distance and abundance of sources to R~29. Questions ! Free format text (please update) Observing_Description: Our observational strategy is similar to that successfully adopted for the Cycle 4 A2218 observations for which we have already undertaken the lensing inversion. Those observations totalled 3 orbits in F702W and were an excellent indication of the capabilities of both the telescope and the inversion method. However, a careful analysis of that data showed that we were compromised by the relatively high surface brightness limit imposed by the short exposure time -- which introduces biases into the object selection of the distorted arclets -- and equally importantly by residual flat-fielding errors from the small number of exposures available to stack. The robust inversion of these observations was thus limited to only R~25, too shallow to reach beyond the break in galaxy number counts. In this proposal we are attempting to probe the redshifts and luminosities of galaxies fainter than the break magnitude, reaching to R~26. We are thus requesting longer integration times to provide a fainter magnitude limit, a deeper limiting isophote for more robust object selection and to obtain more independent pointings to reduce contributions from flat-fielding errors. With 6 orbits per cluster and offsetting each pair of pointings by (1.0,1.0) arcsec we can construct deeper and flatter images and provide a more robust arclet catalog. Our choice of the F702W is dictated by the need for the reddest possible high-sensitivity filter combination, this choice also provides commonality with our A2218 and AC114 exposures. Real_Time_Justification: None. None. Spectroscopy of the brightest arc in this cluster has already been undertaken by ourselves. Extensive ground-based imaging, spectroscopic data for cluster members and deep ROSAT/ASCA observations are also available for this target. Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: ABELL2219 Alternate_Names: Description: CLUSTER OF GALAXIES, GRAVITATIONAL LENS, RICH CLUSTER Position: RA=16H 40M 23.76S +/- 0.1S, ! Most common specification format DEC=+46D 42' 54.4" +/- 2" ! RA=0H 0M 0.00S +/- 0S, ! DEC=0D 0' 0.0" +/- 0", ! PLATE-ID=0000 Equinox: 2000.0 RV_or_Z: Z=0.225 RA_PM: 0.0 ! Units are seconds of time per year Dec_PM: 0.0 ! Units are seconds of arc per year Epoch: 2000.0 Annual_Parallax: 0.0 Flux: R=25.5 V-R=1.5 ! Include at least V and B-V Comments: ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits ! Section 6 Visit_Number: 1 Visit_Requirements: ! Section 7.1 ORIENT 70D TO 95D On_Hold_Comments: Visit_Comments: According to the convention for WFPC2 coordinates as given in the FIXED TARGETS positions are shifted by POS TARG +10.0,+10.0 to bring the center to the apex of the pyramid. Exposures for the field are split into three groups of two exposures each with a shift introduced of (1.0,1.0) arcsec between each pair in order to displace objects situated on CCD defects or on the seams of the pyramid. Thus, POS TARG +11.0,+11.0 corresponds to the second group, POS TARG +9.0,+9.0 to the third. CR-SPLIT=NO for all observations since in all cases there are sufficient multiple exposures to perform cosmic ray rejection. ORIENT range is 80 +15/-10 DEG to keep the target major axis aligned parrallel to the X-axis of WF-4. Final Target Postion may be slightly altered when the roll-angle is fixed to provide optimal coverage of the numerous lensed features in the cluster core. LOW-SKY is selected to provide a low sky background for identification of these very faint objects. Exposure_Number: 1 ! Section 6.5 Target_Name: ABELL2219 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F702W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 2400S Special_Requirements: ! Section 7.2 EXPAND LOW-SKY POS TARG +10.0,+10.0 Comments: POS TARG +10,+10 PLACES TARGET COORDS AT APEX OF PYRAMID. Exposure_Number: 2 ! Section 6.5 Target_Name: ABELL2219 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F702W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 2400S Special_Requirements: ! Section 7.2 EXPAND LOW-SKY POS TARG +11.0,+11.0 Comments: SHIFTED BY 1.0,1.0 TO ALLOW REMOVAL OF CHIP DEFECTS Exposure_Number: 3 ! Section 6.5 Target_Name: ABELL2219 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F702W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 2400S Special_Requirements: ! Section 7.2 EXPAND LOW-SKY POS TARG +9.0,+9.0 Comments: SHIFTED BY -1.0,-1.0 TO ALLOW REMOVAL OF CHIP DEFECTS Data_Distribution ! Defaults indicated; change if desired Medium: 8MM ! 8MM or 6250BPI or 1600BPI Blocking_Factor: 10 ! 10 or 1 ! Only astronomers with very old 9- ! track tape drives should consider ! a blocking factor of 1 Ship_To: PI_Address ! STSCI or PI_Address or ! PI Address from Phase I is: Dept of Physics ! University of Durham ! 813 Santa Barbara Street South Rd ! Pasadena Durham DH1 3LE ! 91101-1292 BRITAIN ! ! Ship_Via: UPS ! UPS (2-day) or OVERNIGHT ! Overnight shipping done at PI expense Recipient_Email: ! Needed if Ship_To: is not PI_Address !