11993( 3) - 06-Feb-2009 15:09:31 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 11993 Version: 3 Check-in Time: 06-Feb-2009 15:09:31 STScI Edit Number: 1 Title High Resolution Imaging of a Binary Supermassive Black Hole Candidate ------------------------------------------------------------------------------------ Type Cycle GO/DD 16 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Tod R. Lauer National Optical Astronomy Observatories, AURA CoI: Dr. Todd A. Boroson National Optical Astronomy Observatories, N AURA ------------------------------------------------------------------------------------ Abstract Dithered high resolution images of a supermassive binary black hole candidate SDSS J153636.22+044127.0 will be obtained with the WFPC2/PC in F675W. This QSO was identified in November, 2008 by a principal components analysis of the ~ 17, 500 QSOs in the SDSS DR7 sample. It is unique among all known QSOs in having two broadline regions, indicative of two supermassive black holes being actively fed. It is the best candidate for a supermassive binary black hole known. Such binaries should be common in the Universe and play key roles in the formation and evolution of galaxies, yet no convincing examples had been identified prior to this QSO. The HST imaging should be able to constrain two alternative hypotheses that this object is 1) the site of a black hole ejected from a nucleus by a multi-body interaction, or 2) a simple line of sight superposition of two unrelated AGN. With the superb spatial resolution of HST, two AGN separated by > 300pc (projected) should be readily visible. ------------------------------------------------------------------------------------ Observations Description ------------------------ The observational goal is to test if the QSO is a pure point source. We will conduct F675W imaging in the PC1 CCD of WFPC2. The observations will be dithered in a 2X2 pattern of 0.5 pixel steps (with a CR-split at each position) to provide a Nyquist-sampled superimage. The final resolution should be ~0.06'' FWHM. The F675W bandpass covers H-beta for both redshift systems, as well as the [O III] lines of the r-system. With the left-over time in the orbit, we have added a single CR-split F439W exposure to add color information and to provide slightly better resolution. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- 11993( 3) - 06-Feb-2009 15:09:31 - [ 2] ------------------------------------------------------------------------------------ 11993( 3) - 06-Feb-2009 15:09:31 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ153636. GALAXY, QSO, QUASAR RA=15H36M36.2200S +/- 0.1", J2000 V = 17.2 +/- 0.05 AB(675W)=16.73 22+044127.0 DEC=+04D41'27.30" +/- 0.1" Reference Frame: ICRS Comments: ------------------------------------------------------------------------------------------------------------------------------------ 11993( 3) - 06-Feb-2009 15:09:31 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFPC2-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.559017 Line_Spacing 0.559017 Coordinate_Frame POS-TARG Pattern_Orient 26.56505 Angle_Between_Sides 143.130102 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 11993( 3) - 06-Feb-2009 15:09:31 - [ 5] Visit: 01 Visit Requirements: PCS MODE FINE 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 SDSSJ153636 WFPC2 IMAGE PC1 F675W ATD-GAIN=7, CR-SPLIT=0.5 1 160 S PATTERN 1 1 .22+044127. 0 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ153636 WFPC2 IMAGE PC1 F439W CR-SPLIT=0.5, ATD-GAIN=7 1 200 S .22+044127. 0 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ153636.22+0441 1 WFPC2 IMAGE PC1 F675W 1 none none 1 1 N/A 27.0 SDSSJ153636.22+0441 1 WFPC2 IMAGE PC1 F675W 1 none none 2 1 N/A 27.0 SDSSJ153636.22+0441 1 WFPC2 IMAGE PC1 F675W 2 none none 1 1 N/A 27.0 SDSSJ153636.22+0441 1 WFPC2 IMAGE PC1 F675W 2 none none 2 1 N/A 27.0 SDSSJ153636.22+0441 1 WFPC2 IMAGE PC1 F675W 3 none none 1 1 N/A 27.0 SDSSJ153636.22+0441 1 WFPC2 IMAGE PC1 F675W 3 none none 2 1 N/A 27.0 SDSSJ153636.22+0441 1 WFPC2 IMAGE PC1 F675W 4 none none 1 1 N/A 27.0 SDSSJ153636.22+0441 1 WFPC2 IMAGE PC1 F675W 4 none none 2 1 N/A 27.0 SDSSJ153636.22+0441 2 WFPC2 IMAGE PC1 F439W none none none 1 1 N/A 27.0 SDSSJ153636.22+0441 2 WFPC2 IMAGE PC1 F439W none none none 2 1 N/A 27.0 11993( 3) - 06-Feb-2009 15:09:31 - [ 6] Summary Form for Proposal 11993 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ATD-GAIN=7, CR-SPLIT=0.5 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PCS MODE FINE ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F439W, F675W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SDSSJ153636.22+044127.0 ------------------------------------------------------------------------------------------------------------------------------------