12493( 2) - 11-Jul-2011 16:38:19 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12493 Version: 2 Check-in Time: 11-Jul-2011 16:38:19 STScI Edit Number: 0 Title A Candidate Lensed Quasar at z=6.25 ------------------------------------------------------------------------------------ Type Cycle GO 19 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Ian McGreer University of Arizona CoI: Prof. Xiaohui Fan University of Arizona N CoI: Dr. Michael A. Strauss Princeton University N CoI: Prof. Zoltan Haiman Columbia University in the City of New N York CoI: Dr. Gordon T. Richards Drexel University N CoI: Dr. Linhua Jiang Arizona State University N CoI: Prof. Donald P. Schneider The Pennsylvania State University N ------------------------------------------------------------------------------------ Abstract We have identified a candidate lensed quasar at z=6.25 through an ongoing Cycle 18 SNAP program surveying z~6 quasars with WFC3/IR imaging. The object is resolved into multiple components on subarcsecond scales; however, the shallow, single-band SNAP data does not provide a conclusive determination as to the nature of these components. We propose follow-up imaging with ACS/WFC F775W and WFC3/IR F105W. This imaging will test various lensing hypotheses for the observed components, and color selection in these two bands will easily discriminate foreground and background objects. Faint objects seen within 0.8'' of the quasar may be lensed images or possibly galaxies at the quasar redshift, indicating the late stages of merging activity. We will take advantage of the full field-of-view to identify companion galaxies to a quasar at one of the highest redshifts known. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will obtain ACS/WFC-F775W and WFC3/IR-F105W imaging of a candidate lensed quasar at z=6.25. The ACS imaging comprises 3 orbits and will primarily be used to detect faint foreground galaxies within the field, at a depth of i(AB)~28.7 (3sigma). Objects at the redshift of the quasar will have very red i-Y colors and can be discriminated from foreground galaxies by i-Y color or i non-detection. The WFC3 imaging comprises 2 orbits and will be used to obtain deep, high-resolution imaging of the quasar, with the goal of deblending components separated by as little as ~0.15''. Part of the second WFC3 orbit will be utilized to observe a nearby PSF star (1' from the quasar) with similar colors as the quasar. The WFC3 imaging will also be the detection band for z~6 galaxies in the field, with a depth of Y(AB)~27. The WFC3 imaging consists of two patterns (4 and 2 dithers) with the using the IR-FIX aperture with a slight offset to avoid the center of the array. The patterns should provide optimal resolution. The same patterns and offsets are 12493( 2) - 11-Jul-2011 16:38:19 - [ 2] repeated for the shorter PSF observations, which use the IRSUB128-FIX aperture and SPARS10 sampling in order to capture the PSF star at high S/N without saturation. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 12493( 2) - 11-Jul-2011 16:38:19 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 CFHQS-J00500 GALAXY, QSO RA=00H50M6.6700S +/- 0.1", J2000 Z = 6.25 z=20.5 (AB) 6+344522 DEC=+34D45'22.60" +/- 0.1" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ005004. STAR, M V-IV RA=00H50M4.8152S +/- 0.1", J2000 J(Vega)=16.8 81+344619.9 DEC=+34D46'19.95" +/- 0.1" Reference Frame: ICRS Comments: PSF star selected based on SDSS/2MASS colors to have a similar SED as the quasar. This star is not above the 2MASS catalog detection limit, but we have determined from aperture photometry that it has J=16.9 and H=15.9. ------------------------------------------------------------------------------------------------------------------------------------ 12493( 2) - 11-Jul-2011 16:38:19 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.572 Line_Spacing 0.365 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 6 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.636 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 41.788 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 7 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: 8 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 ------------------------------------------------------------------------------------------------------------------------------------ 12493( 2) - 11-Jul-2011 16:38:19 - [ 5] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 CFHQS-J0050 ACS/WFC ACCUM WFC F775W 1 1200 S PATTERN 7 1 06+344522 see below ------------------------------------------------------------------------------------------------------------------------------------ 2 CFHQS-J0050 ACS/WFC ACCUM WFC F775W 1 1200 S PATTERN 8 2 06+344522 see below ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ CFHQS-J005006+34452 1 ACS/WFC ACCUM WFC F775W 1 none none none 1 1282.0 S 2 CFHQS-J005006+34452 1 ACS/WFC ACCUM WFC F775W 2 none none none 1 1282.0 S 2 CFHQS-J005006+34452 1 ACS/WFC ACCUM WFC F775W 3 none none none 2 1378.0 S 2 CFHQS-J005006+34452 1 ACS/WFC ACCUM WFC F775W 4 none none none 2 1378.0 S 2 CFHQS-J005006+34452 2 ACS/WFC ACCUM WFC F775W 1 none none none 3 1376.0 S 2 CFHQS-J005006+34452 2 ACS/WFC ACCUM WFC F775W 2 none none none 3 1376.0 S 2 12493( 2) - 11-Jul-2011 16:38:19 - [ 6] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 CFHQS-J0050 WFC3/IR MULTIAC IR-FIX F105W NSAMP=10, SAMP-SEQ=SPARS100 1 DEF POS TARG -0.5, -1.5; 06+344522 CUM PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 CFHQS-J0050 WFC3/IR MULTIAC IR-FIX F105W NSAMP=8, SAMP-SEQ=SPARS100 1 DEF POS TARG 0.326, 1.326; 06+344522 CUM PATTERN 6 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ005004 WFC3/IR MULTIAC IRSUB128- F105W NSAMP=4, SAMP-SEQ=SPARS10 1 DEF POS TARG -0.5, -1.5; .81+344619. CUM FIX PATTERN 2 3 9 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ005004 WFC3/IR MULTIAC IRSUB128- F105W NSAMP=4, SAMP-SEQ=SPARS10 1 DEF POS TARG 0.326, 1.326; .81+344619. CUM FIX PATTERN 6 4 9 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ CFHQS-J005006+34452 1 WFC3/IR MULTIAC IR-FIX F105W 1 none none none 1 N/A 2 CUM CFHQS-J005006+34452 1 WFC3/IR MULTIAC IR-FIX F105W 2 none none none 1 N/A 2 CUM CFHQS-J005006+34452 1 WFC3/IR MULTIAC IR-FIX F105W 3 none none none 1 N/A 2 CUM CFHQS-J005006+34452 1 WFC3/IR MULTIAC IR-FIX F105W 4 none none none 2 N/A 2 CUM CFHQS-J005006+34452 2 WFC3/IR MULTIAC IR-FIX F105W 1 none none none 2 N/A 2 CUM CFHQS-J005006+34452 2 WFC3/IR MULTIAC IR-FIX F105W 2 none none none 2 N/A 2 CUM SDSSJ005004.81+3446 3 WFC3/IR MULTIAC IRSUB128 F105W 1 none none none 2 N/A 19.9 CUM -FIX SDSSJ005004.81+3446 3 WFC3/IR MULTIAC IRSUB128 F105W 2 none none none 2 N/A 19.9 CUM -FIX SDSSJ005004.81+3446 3 WFC3/IR MULTIAC IRSUB128 F105W 3 none none none 2 N/A 19.9 CUM -FIX SDSSJ005004.81+3446 3 WFC3/IR MULTIAC IRSUB128 F105W 4 none none none 2 N/A 19.9 CUM -FIX SDSSJ005004.81+3446 4 WFC3/IR MULTIAC IRSUB128 F105W 1 none none none 2 N/A 19.9 CUM -FIX 12493( 2) - 11-Jul-2011 16:38:19 - [ 7] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ005004.81+3446 4 WFC3/IR MULTIAC IRSUB128 F105W 2 none none none 2 N/A 19.9 CUM -FIX 12493( 2) - 11-Jul-2011 16:38:19 - [ 8] Summary Form for Proposal 12493 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR-FIX, IRSUB128-FIX, WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=10, NSAMP=4, NSAMP=8, SAMP-SEQ=SPARS10, SAMP-SEQ=SPARS100 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 2 1, PATTERN 2 3, PATTERN 6 2, PATTERN 6 4, PATTERN 7 1, PATTERN 8 2, POS TARG -0.5, -1.5, POS TARG 0.326, 1.326 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F105W, F775W ------------------------------------------------------------------------------------------------------------------------------------ Target Names CFHQS-J005006+344522, SDSSJ005004.81+344619.9 ------------------------------------------------------------------------------------------------------------------------------------