10158( 2) - 05/24/04 17:30 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 10158 Version: 2 Check-in Date: 24-May-2004 21:27:20 1.Proposal Title: ACS Observations of the Gravitational Lens B1608+656: Characterizing the Einstein Ring ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle 4. Parallel Pointing Tolerance GO 13 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Prof. Christopher Fassnacht University of California - Davis CoI: Dr. Leon Koopmans Kapteyn Astronomical Institute N CoI: Dr. Tommaso Treu University of California - Los Angeles N CoI: Prof. Roger D. Blandford Stanford University N ------------------------------------------------------------------------------------ 6. Abstract We request time to obtain ACS deep images of the B1608+656 gravitational lens system to fully characterize its enclosing Einstein ring with high signal-to-noise ratio (SNR). These data will allow us to determine the gravitational potential of the lens, locally, to several percent accuracy and, combined with the three independent time delays, measure H_0 to much better than 10% precision. For this goal, we have developed powerful new lens modeling codes that make use of the full brightness distribution of the Einstein ring in lens systems. The B1608+656 system is ideal for our new code. It has precisely measured time delays, a well-determined stellar velocity dispersion, and an Einstein ring that is not dominated by the lensed nuclear emission of the background source. When combined with high-SNR images of Einstein rings, the new modeling codes provide qualitatively different and much improved analysis of the ring emission than was previously possible. The proposed ACS observations will reach the SNR at which the new modeling code can be fully exploited (SNR=5 per pixel). Our simulations show that these new data will allow us to reduce the total uncertainties in H_0 derived from the system by at least a factor of two, to the 5-7% level for this system. ------------------------------------------------------------------------------------ 10158( 2) - 05/24/04 17:30 - [ 2] Observations Description ------------------------ This program has the goal of producing high-sensitivity images of the Einstein ring in the gravitational lens system B1608+656. There are 9 orbits in F814W and 6 orbits in F606W on the lens system. Each orbit consists of one ACS box dither pattern. Two interlocking box patterns have been created. One is the standard ACS-WFC-DITHER-BOX pattern. The second is the same pattern, but with the center pattern parameter set to yes. In addition to the observations on the lens system, there are 2 orbits each on two stars which will be used as PSF stars to deconvolve the ring emission. The PSF stars are observed with a variety of exposure times in order to build up a PSF with both an unsaturated core and high sensitivity wings. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 10158( 2) - 05/24/04 17:30 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 B1608+656 GALAXY, GRAVITATIONAL RA=16H09M14.0S +/- 0.1", J2000 Z = 0.63 V = 19.0 LENS DEC=+65D32'28.0" +/- 0.1" Coordinate Source: Other_Source: VLA observations 2 PG1633+099A STAR, DA RA=16H35M25.95S +/- 0.1", J2000 V = 15.3 DEC=+09D47'53.38" +/- 0.1", B=16.13 PLATE-ID=006K Coordinate Source: GSC_SURVEY_PLATE 3 G138-25 STAR, UNDESIGNATED, M RA=16H25M13.79S +/- 0.1", J2000 V = 13.5 V-IV DEC=+15D41'15.85" +/- 0.1", B=14.9 PLATE-ID=01GC Coordinate Source: GSC_SURVEY_PLATE Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1989.27 0.01 -1.232 0.0 10158( 2) - 05/24/04 17:30 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.265 Line_Spacing 0.187 Coordinate_Frame POS-TARG Pattern_Orient 20.67 Angle_Between_Sides 69.05 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.265 Line_Spacing 0.187 Coordinate_Frame POS-TARG Pattern_Orient 20.67 Angle_Between_Sides 69.05 Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 3.011 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 85.28 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 10158( 2) - 05/24/04 17:30 - [ 5] Visit: 01 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: 2 orbits at F814W and 2 orbits at F606W. Each orbit consists of one dither pattern. The dither patterns are boxes, and the boxes are offset so that they are interlocking. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 B1608+656 ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 609 S PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 B1608+656 ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 646 S PATTERN 2 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 B1608+656 ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 632 S PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 B1608+656 ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 646 S PATTERN 2 4 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 01 1 1 none none none 1 tbd 01 1 2 none none none 1 tbd 01 1 3 none none none 1 tbd 01 1 4 none none none 1 tbd 01 2 1 none none none 2 tbd 01 2 2 none none none 2 tbd 01 2 3 none none none 2 tbd 01 2 4 none none none 2 tbd 01 3 1 none none none 3 tbd 01 3 2 none none none 3 tbd 01 3 3 none none none 3 tbd 01 3 4 none none none 3 tbd 01 4 1 none none none 4 tbd 01 4 2 none none none 4 tbd 01 4 3 none none none 4 tbd 01 4 4 none none none 4 tbd 10158( 2) - 05/24/04 17:30 - [ 6] Visit: 02 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: 2 orbits at F814W and 2 orbits at F606W. Each orbit consists of one dither pattern. The dither patterns are boxes, and the boxes are offset so that they are interlocking. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 B1608+656 ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 609 S PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 B1608+656 ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 646 S PATTERN 2 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 B1608+656 ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 632 S PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 B1608+656 ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 646 S PATTERN 2 4 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 02 1 1 none none none 1 tbd 02 1 2 none none none 1 tbd 02 1 3 none none none 1 tbd 02 1 4 none none none 1 tbd 02 2 1 none none none 2 tbd 02 2 2 none none none 2 tbd 02 2 3 none none none 2 tbd 02 2 4 none none none 2 tbd 02 3 1 none none none 3 tbd 02 3 2 none none none 3 tbd 02 3 3 none none none 3 tbd 02 3 4 none none none 3 tbd 02 4 1 none none none 4 tbd 02 4 2 none none none 4 tbd 02 4 3 none none none 4 tbd 02 4 4 none none none 4 tbd 10158( 2) - 05/24/04 17:30 - [ 7] Visit: 03 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: 2 orbits at F814W and 2 orbits at F606W. Each orbit consists of one dither pattern. The dither patterns are boxes, and the boxes are offset so that they are interlocking. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 B1608+656 ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 609 S PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 B1608+656 ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 646 S PATTERN 2 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 B1608+656 ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 632 S PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 B1608+656 ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 646 S PATTERN 2 4 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 03 1 1 none none none 1 tbd 03 1 2 none none none 1 tbd 03 1 3 none none none 1 tbd 03 1 4 none none none 1 tbd 03 2 1 none none none 2 tbd 03 2 2 none none none 2 tbd 03 2 3 none none none 2 tbd 03 2 4 none none none 2 tbd 03 3 1 none none none 3 tbd 03 3 2 none none none 3 tbd 03 3 3 none none none 3 tbd 03 3 4 none none none 3 tbd 03 4 1 none none none 4 tbd 03 4 2 none none none 4 tbd 03 4 3 none none none 4 tbd 03 4 4 none none none 4 tbd 10158( 2) - 05/24/04 17:30 - [ 8] Visit: 04 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: 2 orbits at F814W and 2 orbits at F606W. Each orbit consists of one dither pattern. The dither patterns are boxes, and the boxes are offset so that they are interlocking. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 B1608+656 ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 609 S PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 B1608+656 ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 646 S PATTERN 2 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 B1608+656 ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 632 S PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 B1608+656 ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 646 S PATTERN 2 4 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 04 1 1 none none none 1 tbd 04 1 2 none none none 1 tbd 04 1 3 none none none 1 tbd 04 1 4 none none none 1 tbd 04 2 1 none none none 2 tbd 04 2 2 none none none 2 tbd 04 2 3 none none none 2 tbd 04 2 4 none none none 2 tbd 04 3 1 none none none 3 tbd 04 3 2 none none none 3 tbd 04 3 3 none none none 3 tbd 04 3 4 none none none 3 tbd 04 4 1 none none none 4 tbd 04 4 2 none none none 4 tbd 04 4 3 none none none 4 tbd 04 4 4 none none none 4 tbd 10158( 2) - 05/24/04 17:30 - [ 9] Visit: 10 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: 3 orbits at F814W and 1 orbits at F606W. Each orbit consists of one dither pattern. Note: This is a different combination of F814W and F606W than that used in visits 01-04. The dither patterns are boxes, and the boxes are offset so that they are interlocking. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 B1608+656 ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 609 S PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 B1608+656 ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 632 S PATTERN 2 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 B1608+656 ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 646 S PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 B1608+656 ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 646 S PATTERN 2 4 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 10 1 1 none none none 1 tbd 10 1 2 none none none 1 tbd 10 1 3 none none none 1 tbd 10 1 4 none none none 1 tbd 10 2 1 none none none 2 tbd 10 2 2 none none none 2 tbd 10 2 3 none none none 2 tbd 10 2 4 none none none 2 tbd 10 3 1 none none none 3 tbd 10 3 2 none none none 3 tbd 10 3 3 none none none 3 tbd 10 3 4 none none none 3 tbd 10 4 1 none none none 4 tbd 10 4 2 none none none 4 tbd 10 4 3 none none none 4 tbd 10 4 4 none none none 4 tbd 10158( 2) - 05/24/04 17:30 - [ 10] Visit: 21 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Exposures on the PSF star PG1633+099A. Box dither patterns of 0.5 and 8 seconds in each of the two filters, plus a 300 second long exposure in F606W, split as a 2-point line dither. In order to avoid the serial dump problem for the short exposures, a subaperture has been used (WFC1-2K). In order to get the PSF star close to the position at which the lens system will be observed in visits 01-10, namely the WFC aperture, a POS TARG offset has been used. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PG1633+099A ACS/WFC ACCUM WFC1-2K F814W CR-SPLIT=NO 1 8 S POS TARG -30,-30; PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 PG1633+099A ACS/WFC ACCUM WFC1-2K F814W CR-SPLIT=NO 1 0.5 S POS TARG -30,-30; PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 PG1633+099A ACS/WFC ACCUM WFC1-2K F606W CR-SPLIT=NO 1 8 S POS TARG -30,-30; PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 PG1633+099A ACS/WFC ACCUM WFC1-2K F606W CR-SPLIT=NO 1 0.5 S POS TARG -30,-30; PATTERN 1 4 ------------------------------------------------------------------------------------------------------------------------------------ 5 PG1633+099A ACS/WFC ACCUM WFC1-2K F606W CR-SPLIT=NO 1 150 S POS TARG -30,-30; PATTERN 3 5 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 21 1 1 none none none 1 tbd 21 1 2 none none none 1 tbd 21 1 3 none none none 1 tbd 21 1 4 none none none 1 tbd 21 2 1 none none none 1 tbd 21 2 2 none none none 1 tbd 21 2 3 none none none 1 tbd 21 2 4 none none none 1 tbd 21 3 1 none none none 1 tbd 21 3 2 none none none 2 tbd 21 3 3 none none none 2 tbd 21 3 4 none none none 2 tbd 21 4 1 none none none 2 tbd 21 4 2 none none none 2 tbd 10158( 2) - 05/24/04 17:30 - [ 11] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 21 4 3 none none none 2 tbd 21 4 4 none none none 2 tbd 21 5 1 none none none 2 tbd 21 5 2 none none none 2 tbd 10158( 2) - 05/24/04 17:30 - [ 12] Visit: 31 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Exposures on the PSF star G138-25. Box dither patterns of 0.5 and 8 seconds in each of the two filters, plus a 300 second long exposure in F814W, split as a 2-point line dither. In order to avoid the serial dump problem for the short exposures, a subaperture has been used (WFC1-2K). In order to get the PSF star close to the position at which the lens system will be observed in visits 01-10, namely the WFC aperture, a POS TARG offset has been used. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 G138-25 ACS/WFC ACCUM WFC1-2K F606W CR-SPLIT=NO 1 8 S POS TARG -30,-25; PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 G138-25 ACS/WFC ACCUM WFC1-2K F606W CR-SPLIT=NO 1 0.5 S POS TARG -30,-25; PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 G138-25 ACS/WFC ACCUM WFC1-2K F814W CR-SPLIT=NO 1 8 S POS TARG -30,-25; PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 G138-25 ACS/WFC ACCUM WFC1-2K F814W CR-SPLIT=NO 1 0.5 S POS TARG -30,-25; PATTERN 1 4 ------------------------------------------------------------------------------------------------------------------------------------ 5 G138-25 ACS/WFC ACCUM WFC1-2K F814W CR-SPLIT=NO 1 150 S POS TARG -30,-25; PATTERN 3 5 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 31 1 1 none none none 1 tbd 31 1 2 none none none 1 tbd 31 1 3 none none none 1 tbd 31 1 4 none none none 1 tbd 31 2 1 none none none 1 tbd 31 2 2 none none none 1 tbd 31 2 3 none none none 1 tbd 31 2 4 none none none 1 tbd 31 3 1 none none none 1 tbd 31 3 2 none none none 2 tbd 31 3 3 none none none 2 tbd 31 3 4 none none none 2 tbd 31 4 1 none none none 2 tbd 31 4 2 none none none 2 tbd 31 4 3 none none none 2 tbd 10158( 2) - 05/24/04 17:30 - [ 13] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 31 4 4 none none none 2 tbd 31 5 1 none none none 2 tbd 31 5 2 none none none 2 tbd 10158( 2) - 05/24/04 17:30 - [ 14] Summary Form for Proposal 10158 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC WFC1-2K ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1 PATTERN 2 2 PATTERN 1 3 PATTERN 2 4 POS TARG -30,-30; PATTERN 1 1 POS TARG -30,-30; PATTERN 1 2 POS TARG -30,-30; PATTERN 1 3 POS TARG -30,-30; PATTERN 1 4 POS TARG -30,-30; PATTERN 3 5 POS TARG -30,-25; PATTERN 1 1 POS TARG -30,-25; PATTERN 1 2 POS TARG -30,-25; PATTERN 1 3 POS TARG -30,-25; PATTERN 1 4 POS TARG -30,-25; PATTERN 3 5 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names B1608+656 PG1633+099A G138-25 ------------------------------------------------------------------------------------------------------------------------------------