10408( 5) - 04/21/05 13:04 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 10408 Version: 5 Check-in Date: 21-Apr-2005 17:03:32 1.Proposal Title: The Extended Emission Region in the Extreme Type-2 QSO IRAS F15307+3252: Scattered QSO Light or Starbursting Companion ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle 4. Parallel Pointing Tolerance GO 13 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Dean C. Hines Space Science Institute CoI: Dr. Paul Smith University of Arizona N CoI: Dr. Michael S. Brotherton University of Wyoming N ------------------------------------------------------------------------------------ 6. Abstract The polarimetry capability of the ACS will be used to image the extended emission in the most extreme Hyperluminous Infrared Galaxy and Type-2 QSO: IRAS F15307+3252. Ground-based imaging polarimetry reveals high polarization, but does not have sufficient spatial resolution to resolve the source of the polarization, much less elucidate its structure. Previous WFPC2 and ACS observations without polarimetry optics reveal at least two companions and extended emission near the QSO. However, the nature of this structure is unknown. It could be powered by starburst light from an interaction, or it may be debris lit by the central misdirected QSO. Our proposed observations will completely remove this uncertainty. If the extended emission is the source of polarized light, the observations will highly constrain its physical structure and enable detailed modeling of this prototypical Type-2 QSO. If it is not the source of polarized light, then the observations combined with previous HST images will place very tight constraints on the stellar population (or line emission) responsible for the emssion. Either way, as the most extreme object of its class, the results will have a fundamental impact on our understanding of the Hyperluminous Infrared Galaxy phenomenon which may be a dominant phase of galaxies and QSOs in the high redshift universe. ------------------------------------------------------------------------------------ 10408( 5) - 04/21/05 13:04 - [ 2] Observations Description ------------------------ We will use the High Resolution Camera (HRC) with the visible polarizers (POL_V) and the F475W band-pass filter to obtain high-resolution (27 mas/pixel) images of F15307+3252 in polarized light. The HRC+POL_V+F606W combination was chosen to obtain the highest spatial resolution in a pass-band that encompasses the maximum observed polarization as measured by our spectropolarimetry. In addition, POL_V+F606W is less affected by instrumental errors caused by the 47.9? reflection off flat mirror M3 inside the ACS (ISR 0101: Walsh), and this combination has been well calibrated by STScI. We have followed the instructions in the Cycle 13 ACS Handbook for planning the observations. To estimate the required orbit allocation, we used the ACS ETC and the S/N formulae for ACS polarimetry from Sparks & Axon (1999, PASP, 111, 1298) log[ sp/P] = -0.102 ? 0.9898log[P*(S/N) /i], ], (where (S/N) i is the S/N of the ith th polarizer image). Because polarization measurements follow the non-Gaussian Rice distribution, accurate polarimetry requires P sp > 4. The minimum polarization observed in our optical spectropolarimetry near 6000 angstrom in F15307+3252 is 20%, but the polarization of the MgII line is much higher, so Hines et al. (1995) argue that the intrinsic polarization after correction for unpolarized light in the aperture is at least 30%-40%. Therefore, the required uncertainty for the ACS observations sp " 0.07?0.1 ( 6-10%). Solving the above equation yields S/N = 12 per polarizer image. The resolved patches of polarized light might have even higher polarization. The extended emission as imaged with WFPC2 by Farrah et al. (2002) has a F814W magnitude 18.7 in a 0.5'' aperture. Using the ACS ETC and assuming uniform surface brightness, a CR-SPLIT for cosmic rays, and the QSO spectrum fit to the polarized light from Hines et al. (1995), we estimate a S/N = 13 per 2x2 pixel box in about 4800 seconds, which is over a single orbit but less than two orbits per polarizer. Using the ACS Handbook as a guide, 6.1 minutes for target acquisition (5.7 for reacquisition), 2.5 minutes overhead for first exposure, and 1.0 minute within the orbit for the next exposures in series, the total wall clock time = (6.1+20+2.5+20+1) + (5.7+20+2.5+20+1) = 49.6 + 49.2 = 98.8 minutes which fits nicely within 2, 54 minute orbits. The object has elongated structure at 55 degrees, which cannot be along the diffraction spikes. We therefore give ranges of ORIENT to avoid the spikes. All 6 orbits must be obtained in sequence. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 10408( 5) - 04/21/05 13:04 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 F15307+3252 GALAXY, ULTRALUMINOUS RA=15H32M44.0520S +/- 0.1", J2000 Z = V = 19.1+/-0.1 IR GAL DEC=+32D42'46.73" +/- 0.1" 0.9265 Coordinate Source: Other_Source: VLA 10408( 5) - 04/21/05 13:04 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-HRC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.15 Line_Spacing 0.098 Coordinate_Frame POS-TARG Pattern_Orient 19.89 Angle_Between_Sides 63.5 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 10408( 5) - 04/21/05 13:04 - [ 5] Visit: 01 Visit Priority: Visit Requirements: PCS MODE FINE; NUMBER OF GYROS 3; SCHED 30%; ORIENT 5.0D TO 16.0 D; ORIENT 95.0D TO 105.0 D; ORIENT 185.0D TO 195.0 D; ORIENT 276.0D TO 286.0 D; SEQ 01, 02, 03 WITHIN 4.1 Orbits 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 F15307+3252 ACS/HRC ACCUM HRC F606W, CR-SPLIT=NO 1 1360 S PATTERN 1 1 POL0V ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ F15307+3252 1 ACS/HRC ACCUM HRC F606W, 1 none none none 1 N/A POL0V F15307+3252 1 ACS/HRC ACCUM HRC F606W, 2 none none none 1 N/A POL0V F15307+3252 1 ACS/HRC ACCUM HRC F606W, 3 none none none 2 N/A POL0V F15307+3252 1 ACS/HRC ACCUM HRC F606W, 4 none none none 2 N/A POL0V 10408( 5) - 04/21/05 13:04 - [ 6] Visit: 02 Visit Priority: Visit Requirements: PCS MODE FINE; NUMBER OF GYROS 3; SCHED 30%; SAME ORIENT AS 01 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 F15307+3252 ACS/HRC ACCUM HRC F606W, CR-SPLIT=NO 1 1360 S PATTERN 1 1 POL60V ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ F15307+3252 1 ACS/HRC ACCUM HRC F606W, 1 none none none 1 N/A POL60V F15307+3252 1 ACS/HRC ACCUM HRC F606W, 2 none none none 1 N/A POL60V F15307+3252 1 ACS/HRC ACCUM HRC F606W, 3 none none none 2 N/A POL60V F15307+3252 1 ACS/HRC ACCUM HRC F606W, 4 none none none 2 N/A POL60V 10408( 5) - 04/21/05 13:04 - [ 7] Visit: 03 Visit Priority: Visit Requirements: PCS MODE FINE; NUMBER OF GYROS 3; SCHED 30%; SAME ORIENT AS 01 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 F15307+3252 ACS/HRC ACCUM HRC F606W, CR-SPLIT=NO 1 1360 S PATTERN 1 1 POL120V ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ F15307+3252 1 ACS/HRC ACCUM HRC F606W, 1 none none none 1 N/A POL120V F15307+3252 1 ACS/HRC ACCUM HRC F606W, 2 none none none 1 N/A POL120V F15307+3252 1 ACS/HRC ACCUM HRC F606W, 3 none none none 2 N/A POL120V F15307+3252 1 ACS/HRC ACCUM HRC F606W, 4 none none none 2 N/A POL120V 10408( 5) - 04/21/05 13:04 - [ 8] Summary Form for Proposal 10408 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures HRC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/HRC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE FINE; NUMBER OF GYROS 3; SCHED 30%; ORIENT 5.0D TO 16.0 D; ORIENT 95.0D TO 105.0 D; ORIENT 185.0D TO 195.0 D; ORIENT 276.0D TO 286.0 D; SEQ 01, 02, 03 WITHIN 4.1 Orbits PATTERN 1 1 PCS MODE FINE; NUMBER OF GYROS 3; SCHED 30%; SAME ORIENT AS 01 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W,POL0V F606W,POL60V F606W,POL120V ------------------------------------------------------------------------------------------------------------------------------------ Target Names F15307+3252 ------------------------------------------------------------------------------------------------------------------------------------