7259( 3) - 06/16/97 16:16 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7259 Version: 3 Check-in Date: 16-Jun-1997 16:15:10 1.Proposal Title: Polarization mapping of the infrared emission from the jet in M87 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle AGN/QUASARS GO 7 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: ROBERT C. THOMSON UNIVERSITY OF HERTFORDSHIRE CoI: Jim Hough University of Hertfordshire N CoI: Simon Garrington Nuffield Radio Astronomy Laboratories N CoI: Tom Muxlow Nuffield Radio Astronomy Laboratories N CoI: Alistair Nelson University of Wales College of Cardiff N CoI: John Sleath University of Wales College of Cardiff N ------------------------------------------------------------------------------------ 6. Abstract The jet in M87 is unusually bright at optical through x-ray wavelengths. Being the closest such optical jet it is a prime target for high resolution imaging with the HST. The jet is highly polarized (20%+) at both radio and optical wavelengths, and a comparison of the ultraviolet (pre-COSTAR FOC) and radio (VLA) polarization maps of the jet revealed a region of strong depolarization immediately adjacent to and downstream from the brightest knot in the jet. This is interpreted as evidence for the interaction of the jet with a dense cloud or filament in the interstellar medium of M87. If correct, then it implies that the jet brightness is primarily determined not by relativistic beaming, but by its interaction with the interstellar medium of the host galaxy. We propose to use NICMOS to map the polarization of the jet at infrared wavelengths - intermediate between the ultraviolet and radio wavelengths used previously. We will compare these new infrared data with VLA radio archive data, new MERLIN radio data, our pre-COSTAR FOC ultraviolet data, and post-COSTAR FOC ultraviolet archive data to produce high resolution spectral index, depolarization and rotation measure maps of the jet. We will use these maps to investigate the origin of the jet emission and, in particular, to look for any evidence of a jet-cloud interaction. ------------------------------------------------------------------------------------ 7259( 3) - 06/16/97 16:16 - [ 2] Observations Description ------------------------ We propose to use both Camera 1 (NIC1) and Camera 2 (NIC2) of NICMOS to obtain high spatial resolution imaging polarimetry of the M87 jet in the wavelength ranges 0.8micron - 1.3micron (NIC1) and 1.9micron - 2.1micron (NIC2) as defined with the polarizing filters. We propose to accomplish this in two visits. Firstly using NIC1 to image our primary target - the main jet between 10 - 21 arcsec west of the nucleus - through each polarizer in turn. At the same time, NIC2 will image the eastern hotspot 20 arcsec east of the nucleus, again using each polarizer in turn. On the second visit, we will use NIC2 to image the main jet, and NIC1 will image the eastern hotspot. In either case, Camera 3 would be employed for one of the attached parallel programs, as described in the NICMOS Instrument Handbook. Assuming only photon shot noise (ie, signal to noise ratio S/N=sqrtN), the uncertainty in the measured fractional polarization is given by sqrt2/N, where N is the total number of counts in all three polarized images (Thomson & Robinson 1995, ST-ECF Newsletter No. 23, 33). This generalises to sqrt[2/(S/N)] in the presence of additional background counts. To detect >4% polarization, we therefore require a total S/N=35, or equivalently S/N=20 per resolution element in each of the individual polarized images. Taking a resolution element of 2*2 pixels, we therefore require a S/N per pixel of 10. Background subtraction will be done for each polarized image by fitting a smooth surface to the underlying sky plus galaxy which will be present over most of the frame (NB. the jet is only 1 arcsec wide). Proposed observations with NIC1 For exposure time estimation, we use the surface brightness of Knot B (Stiavelli et al, 1996, preprint) that is typical of the jet. The J band surface brightness of Knot B is 0.18 mJy arcsec^-2. Using the NICMOS exposure time software, we estimate an exposure time of 2000 sec per polarizer. The total exposure required with NIC1 is therefore 6000 secs. Proposed observations with NIC2 The K band surface brightness of Knot B is 0.27 mJy arcsec^-2. Using the NICMOS exposure time software, we estimate a similar exposure time of 2000 sec per polarizer. The total exposure time required with NIC2 is therefore 6000 secs. vspace*0.3cm Assuming a target visibility of 52 mins per orbit, and a target re-acquisition time of 6 mins, plus an estimated instrument overhead of up to 2 minutes, the maximum orbital exposure will be 2640 secs. We are therefore asking for exposures lasting over 1 orbit for each polarizer of NIC1, and the same for NIC2. The total allocation we are requesting for this program is 6 orbits. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- See visit comments. ------------------------------------------------------------------------------------ 7259( 3) - 06/16/97 16:16 - [ 3] Data Distribution Media: DAT Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7259( 3) - 06/16/97 16:16 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4486-JET GALAXY,ELLIPTICAL,RADIO RA=187.70188D +/- J2000 SURF(J) = 17.4 GALAXY 0.0003D,DEC=12.39263D +/- SURF(K) = 15.9 0.0003D,PLATE-ID=00IY Comments: The target position is the same as that used by Biretta (Program ID: 5941) to image the outer jet in M87 using the FOC (viz: position M87-JET-POS3). 7259( 3) - 06/16/97 16:16 - [ 5] Visit: 01 Visit Requirements: PCS MODE FINE ORIENT 157D TO 163D On Hold Comments: Additional Comments: Primary target (the main jet on the western side of M87) centred in NIC2. Secondary target (the eastern hotspot in M87) in NIC1. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4486-JET NIC2 MULTIAC NIC2-FI POL0L SAMP-SEQ=SPARS256,NSAMP=12 1 DEF PAR 2 WITH 1 CUM X ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC4486-JET NIC1 MULTIAC NIC1-FI POL0S SAMP-SEQ=SPARS256,NSAMP=12 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC4486-JET NIC2 MULTIAC NIC2-FI POL120L SAMP-SEQ=SPARS256,NSAMP=13 1 DEF PAR 4 WITH 3 CUM X ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC4486-JET NIC1 MULTIAC NIC1-FI POL120S SAMP-SEQ=SPARS256,NSAMP=13 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC4486-JET NIC2 MULTIAC NIC2-FI POL240L SAMP-SEQ=SPARS256,NSAMP=13 1 DEF PAR 6 WITH 5 CUM X ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC4486-JET NIC1 MULTIAC NIC1-FI POL240S SAMP-SEQ=SPARS256,NSAMP=13 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 7259( 3) - 06/16/97 16:16 - [ 6] Visit: 02 Visit Requirements: PCS MODE FINE ORIENT 160D TO -160D FROM 01 On Hold Comments: Additional Comments: I had to specify a wider tolerance in the ORIENTation Special Requirement for this visit which RPS2 otherwise reported as unschedulable. I wanted to rotate the NIC1-NIC2 apertures by 180 +/- 10 degrees using ORIENT 170D TO - 170D FROM 1, but had to settle for 180 +/- 20 degrees using ORIENT 160D TO - 160D FROM 1. NB. This does not affect our primary science program (the main jet on the western side of M87), but it does mean that our our secondary target (the eastern hotspot in M87) may be outside the NIC2 field of view during visit 2. Although not an essential observation, please let me know if it is possible to reduce the tolerance from 20 to 10 degrees. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4486-JET NIC1 MULTIAC NIC1-FI POL0S SAMP-SEQ=SPARS256,NSAMP=12 1 DEF PAR 2 WITH 1 CUM X ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC4486-JET NIC2 MULTIAC NIC2-FI POL0L SAMP-SEQ=SPARS256,NSAMP=12 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC4486-JET NIC1 MULTIAC NIC1-FI POL120S SAMP-SEQ=SPARS256,NSAMP=13 1 DEF PAR 4 WITH 3 CUM X ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC4486-JET NIC2 MULTIAC NIC2-FI POL120L SAMP-SEQ=SPARS256,NSAMP=13 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC4486-JET NIC1 MULTIAC NIC1-FI POL240S SAMP-SEQ=SPARS256,NSAMP=13 1 DEF PAR 6 WITH 5 CUM X ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC4486-JET NIC2 MULTIAC NIC2-FI POL240L SAMP-SEQ=SPARS256,NSAMP=13 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 7259( 3) - 06/16/97 16:16 - [ 7] Summary Form for Proposal 7259 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC2 NIC1 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMP-SEQ=SPARS256 NSAMP=12 NSAMP=13 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category AGN/QUASARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE FINE ORIENT 157D TO 163D PAR 2 WITH 1 PAR 4 WITH 3 PAR 6 WITH 5 PCS MODE FINE ORIENT 160D TO -160D FROM 01 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements POL0L POL0S POL120L POL120S POL240L POL240S ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC4486-JET ------------------------------------------------------------------------------------------------------------------------------------