6560( 6) - 12/01/98 13:03 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6560 Version: 6 Check-in Date: 01-Dec-1998 13:03:16 1.Proposal Title: Mapping an optical Einstein ring ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 6 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Stephen Warren Imperial College of Science, Technology & Medicine CoI: Dr. P. C. Hewett Institute of Astronomy N CoI: Dr. P. Moller Space Telescope Science Institute N CoI: Dr. G. F. Lewis Institute of Astronomy N ------------------------------------------------------------------------------------ 5. Abstract Observations of gravitationally lensed Einstein-ring images provide a dramatic improvement in our ability to constrain the properties of lensing mass distributions and the structure in the extended sources. The rings are so effective, relative to the more common multiply-imaged point sources, because of the constraints provided by the two-dimensional surface brightness maps obtained from high-resolution imaging. The first five known rings were discovered in radio surveys and are all very faint optically. The first optically bright ring, recently discovered spectroscopically and confirmed by imaging, is clearly a prime target for HST imaging. Here we propose a WFPC2 image through the F555W filter to provide a resolved surface-brightness map of the ring and the lensing galaxy. The lens is an early-type galaxy at z=0.485, and the source is an emission-line galaxy at z=3.591. The goal of these observations is twofold: a) to measure the radial profile of the mass-to-light ratio of the lensing galaxy, and b) to determine the structure of the background high-redshift galaxy, at a resolution of 0.2 arcsec. ------------------------------------------------------------------------------------ 6560( 6) - 12/01/98 13:03 - [ 2] Observations Description ------------------------ Four orbits broad band V imaging of the same target, comprising eight dithered images. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- Our original request was for 16 orbits with the F547M filter, which is optimal for imaging the ring itself. Instead we were awarded only 4 orbits to obtain the surface brightness profile of the lensing galaxy. This is better achieved with the broader F555W filter, which we have therefore selected. ------------------------------------------------------------------------------------ Data Distribution Paper Products: Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 6560( 6) - 12/01/98 13:03 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GAL-004942- GALAXY, ELLIPTICAL, RA=0H 49M 41.80S +/- 0.10S, DEC= J2000 Z=0.485 V = 20.4 275226 GRAVITATIONAL LENS, -27D 52' 26.0" +/- 1.0", PLATE- B-V = 1.5 EINSTEIN RING ID=025A 6560( 6) - 12/01/98 13:03 - [ 4] Visit: 01 Visit Priority: Visit Requirements: ORIENT 45.0D TO 90.0D On Hold Comments: Additional Comments: The purpose of the orientation requirement is to image a second galaxy in WF3. The position of this second galaxy relative to the target galaxy is distance 58 arcsec, and position angle 201 deg. With this range of orientation the second galaxy image should not be affected by charge bleeding or diffraction spikes from a bright star that will also lie in WF3. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 GAL-004942- WFPC2 IMAGE WF4-FIX F555W CR-SPLIT=NO 1 1100.00 275226 ------------------------------------------------------------------------------------------------------------------------------------ 2 GAL-004942- WFPC2 IMAGE WF4-FIX F555W CR-SPLIT=NO 1 1200.00 275226 ------------------------------------------------------------------------------------------------------------------------------------ 3 GAL-004942- WFPC2 IMAGE WF4-FIX F555W CR-SPLIT=NO 1 1200.00 POS TARG +0.5,+0.25 275226 ------------------------------------------------------------------------------------------------------------------------------------ 4 GAL-004942- WFPC2 IMAGE WF4-FIX F555W CR-SPLIT=NO 1 1200.00 POS TARG +0.5,+0.25 275226 ------------------------------------------------------------------------------------------------------------------------------------ 5 GAL-004942- WFPC2 IMAGE WF4-FIX F555W CR-SPLIT=NO 1 1200.00 POS TARG +0.75,+0.75 275226 ------------------------------------------------------------------------------------------------------------------------------------ 6 GAL-004942- WFPC2 IMAGE WF4-FIX F555W CR-SPLIT=NO 1 1200.00 POS TARG +0.75,+0.75 275226 ------------------------------------------------------------------------------------------------------------------------------------ 7 GAL-004942- WFPC2 IMAGE WF4-FIX F555W CR-SPLIT=NO 1 1200.00 POS TARG +0.25,+0.5 275226 ------------------------------------------------------------------------------------------------------------------------------------ 8 GAL-004942- WFPC2 IMAGE WF4-FIX F555W CR-SPLIT=NO 1 1200.00 POS TARG +0.25,+0.5 275226 ------------------------------------------------------------------------------------------------------------------------------------ 6560( 6) - 12/01/98 13:03 - [ 5] Summary Form for Proposal 6560 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WF4-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 45.0D TO 90.0D POS TARG +0.5,+0.25 POS TARG +0.75,+0.75 POS TARG +0.25,+0.5 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W ------------------------------------------------------------------------------------------------------------------------------------ Target Names GAL-004942-275226 ------------------------------------------------------------------------------------------------------------------------------------