7337( 10) - 02/04/99 13:30 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7337 Version: 10 Check-in Date: 04-Feb-1999 13:30:09 1.Proposal Title: The central mass profile in the lowest redshift cluster lenses ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Andrew Fabian Institute of Astronomy CoI: Dr Steve Allen Institute of Astronomy, University of N Cambridge CoI: Dr Jean-Paul Kneib Observatoire du Pic de Midi N ------------------------------------------------------------------------------------ 5. Abstract The X-ray luminous cluster of galaxies around the radio source PKS 0745-191 produces the brightest gravitational arc known, with an I band magnitude of 17.7, and has several other possible, unresolved arcs. We propose to image the core of this cluster, an d A478, another massive low redshift cluster with suspected arcs, to map the dark mass profile at radii of ~ 30-100 kpc from the central galaxy. The excellent X-ray data on the clusters, which appear relaxed with no large-scale substructure, means that th e potential is smooth, and is well determined on larger scales. The proposed observations will enable us to determine how it changes to match with that of the central galaxy, using the distortion of the lensed objects. We shall also obtain a detailed map of the redshift 0.433 lensed galaxy in PKS0745 and emission and absorption structures in the central galaxy of both clusters. ------------------------------------------------------------------------------------ 7337( 10) - 02/04/99 13:30 - [ 2] Observations Description ------------------------ We will observe PKS0745-191 and ABELL478 for 1 full orbit in each of the R (F702W) and V (F555W) filters (making 4 orbits of observation in total). The target positions supplied are the optical centroids of the central cluster galaxies, which mark the cen ters of the mass and arc(let) distributions in the two clusters. For PKS0745-191 we will use the WF3-FIX aperture, placing the central galaxy at the geometric centre of WFC CCD3. The bightest arcs in PKS0745-191, which are at radii of less than 25 arcse c, should then all be observed in CCD3. For ABELL478, for which the brightest arcs are observed at larger radii (more than 30 arcsec) we will use the WFALL aperture. For PKS0745- 191 the brightest arc (called A) is 17.7 in I and 21 in V. For the R band fil ter we estimate that the mean surface brightness is about 21.5 mag per square arcsec. We can then detect it in WFC pixels at a S/N of approximately 8 per orbit. The high reddening means that the V exposure will not allow match ing S/N. However, the V exposures are important for distinguishing between intrinsic and extrinsic (lens) structures in the arcs. The data will permit unambiguous identification of fainter arcs, unresolved by ground-based data, and reveal their propertie s. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7337( 10) - 02/04/99 13:30 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PKS0745-191 CLUSTER OF GALAXIES, RA=7H 47M 31.30S +/- 0.1S, DEC=- J2000 Z=0.1028 SURF(V) = 16.0+/-1.0 RICH CLUSTER, 19D 17' 40.0" +/- 1.0" SURF(B) = 17.0+/-1.0 GRAVITATIONAL LENS E(B-V) = 0.7+/-0.2 2 ABELL478 CLUSTER OF GALAXIES, RA=4H 13M 25.27S +/- 0.1S, J2000 Z=0.088 SURF(V) = 16.0+/-1.0 RICH CLUSTER, DEC=10D 27' 53.8" +/- 1.0" SURF(B) = 17.0+/-1.0 GRAVITATIONAL LENS E(B-V) = 0.7+/-0.2 7337( 10) - 02/04/99 13:30 - [ 4] Visit: 01 Visit Priority: 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 PKS0745-191 WFPC2 IMAGE WF3-FIX F814W CR-SPLIT=NO,DITHER-TYPE=LINE, 1 600 S DITHER-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 2 PKS0745-191 WFPC2 IMAGE WF3-FIX F555W CR-SPLIT=NO,DITHER-TYPE=LINE, 1 700 S DITHER-LINE-STEPS=2 ------------------------------------------------------------------------------------------------------------------------------------ 3 PKS0745-191 WFPC2 IMAGE WF3-FIX F555W CR-SPLIT=NO 1 700 S ------------------------------------------------------------------------------------------------------------------------------------ 7337( 10) - 02/04/99 13:30 - [ 5] Visit: 02 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 4 ABELL478 WFPC2 IMAGE WFALL F814W CR-SPLIT=NO,DITHER-TYPE=LINE, 1 600 S DITHER-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 5 ABELL478 WFPC2 IMAGE WFALL F555W CR-SPLIT=NO,DITHER-TYPE=LINE, 1 700 S DITHER-LINE-STEPS=2 ------------------------------------------------------------------------------------------------------------------------------------ 6 ABELL478 WFPC2 IMAGE WFALL F555W CR-SPLIT=NO 1 700 S ------------------------------------------------------------------------------------------------------------------------------------ 7337( 10) - 02/04/99 13:30 - [ 6] Summary Form for Proposal 7337 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WF3-FIX WFALL ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO DITHER-TYPE=LINE DITHER-LINE-STEPS=3 DITHER-LINE-STEPS=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F555W ------------------------------------------------------------------------------------------------------------------------------------ Target Names PKS0745-191 ABELL478 ------------------------------------------------------------------------------------------------------------------------------------