12240( 3) - 14-Jul-2010 17:00:19 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12240 Version: 3 Check-in Time: 14-Jul-2010 17:00:19 STScI Edit Number: 1 Title ACS polarimetry of the Vela Pulsar Wind Nebula ------------------------------------------------------------------------------------ Type Cycle GO 18 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Oleg Y. Kargaltsev University of Florida CoI: Dr. George G. Pavlov The Pennsylvania State University N CoI: Prof. Jeff J. Hester Arizona State University N ------------------------------------------------------------------------------------ Abstract Observations of the Vela pulsar region with the Chandra X-ray observatory have revealed the fine structure of its synchrotron pulsar-wind nebula (PWN). Deep radio observations have also shown a large, highly polarized (~70%) radio nebula located further away from the pulsar. However, no firm optical detection of the Vela PWN has been reported yet. The detection of the extended emission in previous observations was hindered by the presence of a bright background due to SNR filaments and field stars. Since the degree of polarization in the optical should be similar to that observed in radio, we propose to use the ACS/WFC imaging polarimetry to detect the highly polarized optical emission from the Vela PWN. By subtracting the images obtained with different polarizers we will eliminate the very weakly polarized background component and preserve the strongly polarized PWN emission. Polarimetry will allow us to determine the magnetic field structure inside the PWN. This approach has been successfully tested with ASC/WFC polarimetry of the Crab PWN. Detection of the optical nebula, combined with the radio and X-ray data, will establish the properties of the relativistic pulsar wind, including its energetics, magnetic field structure, spatial evolution and interaction with the ambient medium. ------------------------------------------------------------------------------------ Observations Description ------------------------ The purpose of this proposal is to obtain polarization observations of the Vela synchrotron nebula in 5 visits with ACS/WFC. First visit consists of 4 orbits. During one of the orbits a CR-SPLIT image is obtained with F550M, an almost line-free continuum filter. This exposure will provide an image of the total intensity from the synchrotron nebula, with little contamination from emission-line filaments. The other three orbits obtain CR-SPLIT F606W images crossed with POL0V, POL60V, and POL120V. The "WFC1-2K" aperture is used with F550M, while the "WFC" aperture is used with F606W+POL0V, F606W+POL60V and F606W+POL120V. This should put the object at the same place on the WFC [reference pixel (3096, 1024)] for all the four exposures. The remaining visits (2nd through the 5th) consist of 3 orbits each, with polarizing filters only (i.e. no imaging with F550M). The only special requirement is that the position and orientation be the same for each of the three polarizer images taken during each visit, which is needed to extract most reliable polarization information. We intentionally choose to point at RA=08 35 20.86, DEC=-45 10 44.90, i.e. 10'' south of the Vela pulsar since optical synchrotron emission is expected to be brighter in this direction. We also request to schedule the visits as close to 12240( 3) - 14-Jul-2010 17:00:19 - [ 2] each other as possible since having similar Roll Angle values for all visits would simplify the analysis of the polarimetric data and provide more accurate results. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 12240( 3) - 14-Jul-2010 17:00:19 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 VELAPWN ISM, JET, SNR, WIND RA=08H35M20.8600S +/- 0.2", J2000 V=27 mag arcsec^-2 DEC=-45D10'44.90" +/- 0.2" Reference Frame: ICRS Comments: Our target is an extended source, hence pointing accuracy of ~1 arcsec is sufficient. We intentionally point 10'' south of the Vela pulsar. The target coordinates are based on HST images. We request that the position and orientation of the target be the same for each of the three polarizer images taken during each visit. We also request to schedule the visits as close to each other as possible since having similar Roll Angle values for all visits would simplify the analysis of the polarimetric data and provide more accurate results. ------------------------------------------------------------------------------------------------------------------------------------ 12240( 3) - 14-Jul-2010 17:00:19 - [ 4] 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 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL0V see below ------------------------------------------------------------------------------------------------------------------------------------ 2 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL60V see below ------------------------------------------------------------------------------------------------------------------------------------ 3 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL120V see below ------------------------------------------------------------------------------------------------------------------------------------ 4 VELAPWN ACS/WFC ACCUM WFC1-2K F550M CR-SPLIT=2 1 2333.0 S 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 | ------------------------------------------------------------------------------------------------------------------------------------ VELAPWN 1 ACS/WFC ACCUM WFC F606W, none none none 1 1 1299.5 S POL0V VELAPWN 1 ACS/WFC ACCUM WFC F606W, none none none 2 1 1299.5 S POL0V VELAPWN 2 ACS/WFC ACCUM WFC F606W, none none none 1 2 1386.5 S POL60V VELAPWN 2 ACS/WFC ACCUM WFC F606W, none none none 2 2 1386.5 S POL60V VELAPWN 3 ACS/WFC ACCUM WFC F606W, none none none 1 3 1386.5 S POL120V VELAPWN 3 ACS/WFC ACCUM WFC F606W, none none none 2 3 1386.5 S POL120V VELAPWN 4 ACS/WFC ACCUM WFC1-2K F550M none none none 1 4 1362.5 S VELAPWN 4 ACS/WFC ACCUM WFC1-2K F550M none none none 2 4 1362.5 S 12240( 3) - 14-Jul-2010 17:00:19 - [ 5] Visit: 02 Visit Requirements: ORIENT -2.0D TO 2.0D FROM 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 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL0V see below ------------------------------------------------------------------------------------------------------------------------------------ 2 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL60V see below ------------------------------------------------------------------------------------------------------------------------------------ 3 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL120V 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 | ------------------------------------------------------------------------------------------------------------------------------------ VELAPWN 1 ACS/WFC ACCUM WFC F606W, none none none 1 1 1299.5 S POL0V VELAPWN 1 ACS/WFC ACCUM WFC F606W, none none none 2 1 1299.5 S POL0V VELAPWN 2 ACS/WFC ACCUM WFC F606W, none none none 1 2 1386.5 S POL60V VELAPWN 2 ACS/WFC ACCUM WFC F606W, none none none 2 2 1386.5 S POL60V VELAPWN 3 ACS/WFC ACCUM WFC F606W, none none none 1 3 1386.5 S POL120V VELAPWN 3 ACS/WFC ACCUM WFC F606W, none none none 2 3 1386.5 S POL120V 12240( 3) - 14-Jul-2010 17:00:19 - [ 6] Visit: 03 Visit Requirements: ORIENT -2.0D TO 2.0D FROM 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 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL0V see below ------------------------------------------------------------------------------------------------------------------------------------ 2 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL60V see below ------------------------------------------------------------------------------------------------------------------------------------ 3 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL120V 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 | ------------------------------------------------------------------------------------------------------------------------------------ VELAPWN 1 ACS/WFC ACCUM WFC F606W, none none none 1 1 1299.5 S POL0V VELAPWN 1 ACS/WFC ACCUM WFC F606W, none none none 2 1 1299.5 S POL0V VELAPWN 2 ACS/WFC ACCUM WFC F606W, none none none 1 2 1386.5 S POL60V VELAPWN 2 ACS/WFC ACCUM WFC F606W, none none none 2 2 1386.5 S POL60V VELAPWN 3 ACS/WFC ACCUM WFC F606W, none none none 1 3 1386.5 S POL120V VELAPWN 3 ACS/WFC ACCUM WFC F606W, none none none 2 3 1386.5 S POL120V 12240( 3) - 14-Jul-2010 17:00:19 - [ 7] Visit: 04 Visit Requirements: ORIENT -2.0D TO 2.0D FROM 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 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL0V see below ------------------------------------------------------------------------------------------------------------------------------------ 2 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL60V see below ------------------------------------------------------------------------------------------------------------------------------------ 3 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL120V 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 | ------------------------------------------------------------------------------------------------------------------------------------ VELAPWN 1 ACS/WFC ACCUM WFC F606W, none none none 1 1 1299.5 S POL0V VELAPWN 1 ACS/WFC ACCUM WFC F606W, none none none 2 1 1299.5 S POL0V VELAPWN 2 ACS/WFC ACCUM WFC F606W, none none none 1 2 1386.5 S POL60V VELAPWN 2 ACS/WFC ACCUM WFC F606W, none none none 2 2 1386.5 S POL60V VELAPWN 3 ACS/WFC ACCUM WFC F606W, none none none 1 3 1386.5 S POL120V VELAPWN 3 ACS/WFC ACCUM WFC F606W, none none none 2 3 1386.5 S POL120V 12240( 3) - 14-Jul-2010 17:00:19 - [ 8] Visit: 05 Visit Requirements: ORIENT -2.0D TO 2.0D FROM 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 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL0V see below ------------------------------------------------------------------------------------------------------------------------------------ 2 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL60V see below ------------------------------------------------------------------------------------------------------------------------------------ 3 VELAPWN ACS/WFC ACCUM WFC F606W, CR-SPLIT=2 1 2333.0 S POL120V 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 | ------------------------------------------------------------------------------------------------------------------------------------ VELAPWN 1 ACS/WFC ACCUM WFC F606W, none none none 1 1 1299.5 S POL0V VELAPWN 1 ACS/WFC ACCUM WFC F606W, none none none 2 1 1299.5 S POL0V VELAPWN 2 ACS/WFC ACCUM WFC F606W, none none none 1 2 1386.5 S POL60V VELAPWN 2 ACS/WFC ACCUM WFC F606W, none none none 2 2 1386.5 S POL60V VELAPWN 3 ACS/WFC ACCUM WFC F606W, none none none 1 3 1386.5 S POL120V VELAPWN 3 ACS/WFC ACCUM WFC F606W, none none none 2 3 1386.5 S POL120V 12240( 3) - 14-Jul-2010 17:00:19 - [ 9] Summary Form for Proposal 12240 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC, WFC1-2K ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT -2.0D TO 2.0D FROM 01 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F550M, F606W, POL0V, POL120V, POL60V ------------------------------------------------------------------------------------------------------------------------------------ Target Names VELAPWN ------------------------------------------------------------------------------------------------------------------------------------