5918( 7) - 06/21/96 22:21 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5918 Version: 7 Check-in Date: 21-Jun-1996 22:18:45 1.Proposal Title: Imaging polarimetry of the Narrow Line Region of Seyfert galaxies ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle AGN GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: David J. Axon SPACE TELESCOPE SCIENCE INSTITUTE CoI: Alessandro Capetti Space Telescope Science Institute N CoI: Duccio Macchetto Space Telescope Science Institute N CoI: William B. Sparks Space Telescope Science Institute N ------------------------------------------------------------------------------------ 6. Abstract defEtal et al. We propose to unveil the origin of the polarization of forbidden lines observed in Seyfert galaxies by performing imaging polarimetry of the Narrow Line Region (NLR) of three nearby Seyfert 2 galaxies. The origin of the polarization of the narrow lines is not understood. HST imaging polarimetry of NGC 1068 has shown that the polarization of the forbidden lines in this galaxy is due to scattering, by analogy with the continuum and the permitted lines polarization. When trying to establish the properties of the NLR, it is fundamental to understand the relevance of line scattering in Seyfert galaxies. If NGC 1068 is typical, and we believe it is, the overall structure of the NLR is dramatically influenced by scattering: light produced in the brightest region of line emission is reverberated within the whole nuclear region and can actually dominate the NLR. The observed morphology of the NLR does not correspond to the true distribution of line-emitting gas but rather to a mixture of emitting and reflecting media. Imaging polarimetry allows us to disentangle intrinsic and scattered emission and to determine the true distribution of the emitting gas and the reflecting medium. The information we will obtain on the nature and distribution of the scattering material is crucial in the framework of the unified models for Seyfert galaxies. ------------------------------------------------------------------------------------ 5918( 7) - 06/21/96 22:21 - [ 2] Observations Description ------------------------ Three objects have been chosen for this project, Mrk 3, Mrk 78 and IC 5063. They belong to the sample of Seyfert galaxies where polarized broad lines have been detected, which indicates that scattering is indeed important. To increase the efficiency of the program, the three brightest objects that lie in the Continuous Viewing Zones have been selected. These galaxies will be imaged using the FOC with the filter F502M combined with the three polarizers. The F502M includes the Oxygen lines O IIILambdaLambda4959,5007. The continuum emission in this wavelength range is expected to significantly polarized (~ 2 \\ the analysis of archival HST images shows that the continuum emission contributes for only ~ 10 \\ contribution of the continuum polarized flux is negligible. Observations in adjacent band are available and will be used to subtract the residual continuum contribution from our images. The FOC was preferred to WFPC2 for these observations for several reasons. Polarimetry with WFPC2 must be performed either taking images in four different cameras (which introduces uncertainties due to the relative photometric calibration) or using the non-optimal polarization angles available. In addition the spatial resolution of the FOC is vastly superior and it offers a better filter selection. Using the FOC, the polarization images will be derived using three polarizers at different polarization angles. The count rate for these objects never exceeds the linearity limit for the FOC. The accuracy of the polarization measurements is only limited by photons statistics. The exposure time calculation is based on previous HST FOC/COSTAR images for two of the objects, Mrk 3 and Mrk 78, while ground based observations have been used for IC 5063. As an example, in Fig. 1 we show the expected number of counts in each polarizer in the case of Mrk 3 for a 85 minutes exposure through the F502M+POL0 filter. Since we selected only objects within the CV Zones, only three orbits are needed to obtain three of these exposures. To achieve an accuracy of ~ 2\\ measurements, about 1600 counts in each polarizer are needed. Given the estimated count rate this number will be reached on the brightest regions co- adding the pixels 2 by 2. On the extended and weaker regions the same result will be obtained co-adding 8 x 8 pixels, corresponding to ~ 0".1 resolution. Analogous results will be obtained for Mrk 78 in five orbits while for IC5603 three orbits will sufficient. . 8truecm Fig. 1: total counts for a 85 minutes exposure of Mrk3. Contours are plotted at 25,100 and 400 counts per pixel. These corresponds to integration regions of 8 x 8, 4 x 4 and 2 x 2 pixels (indicated on the image with the filled squares) to achieve an error of less than 2 \\ Real Time Justification ----------------------- None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 5918( 7) - 06/21/96 22:21 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5918( 7) - 06/21/96 22:21 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 3 MRK3 GALAXY,SEYFERT RA=06H 15M 36.33S +/- 0.01S, 2000 V = 14.0+/-0.1 DEC=+71D 02' 15.4" +/- 0.1" 6 MRK78 GALAXY,SEYFERT RA=07H 42M 41.60S +/- 0.01S, 2000 V = 15.0+/-0.1 DEC=+65D 10' 35.62" +/- 0.01" 7 IC5063 GALAXY,SEYFERT RA=20H 52M 02.22S +/- 0.10S, 2000 V = 12.9+/-0.1 DEC=-57D 04' 07.0" +/- 1.00", PLATE-ID=03BT Comments: The coords have been measured by W. Sparks from Malkan's SNAP image, however it is not known which GS plate was the one from which the guide stars used for Malkan's SNAP were taken. Since the nucleus is somewhat obscured in this galaxy anyway, and the optimal pointing therefore somewhat uncertain, the PI has decided today ( 21 June, 1996 ) to just use the coords measured by W. Sparks from Malkan's SNAP together with the GS Plate ID from the GASP finder chart. Although this may lead to some inconsistency between the two if the chart was not made from the same GS plate as that used for Malkan's guide stars, the PI has decided that the uncertainty due to the obscured nucleus negates any need to make the coords more accurate than they already are. 5918( 7) - 06/21/96 22:21 - [ 5] Visit: 01 Visit Requirements: CVZ On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 MRK3 FOC/96 IMAGE 512X512 F502M, 1 5265 S POL0 ------------------------------------------------------------------------------------------------------------------------------------ 12 MRK3 FOC/96 IMAGE 512X512 F502M, 1 5265 S POL60 ------------------------------------------------------------------------------------------------------------------------------------ 13 MRK3 FOC/96 IMAGE 512X512 F502M, 1 5265 S POL120 ------------------------------------------------------------------------------------------------------------------------------------ 5918( 7) - 06/21/96 22:21 - [ 6] Visit: 02 Visit Requirements: CVZ On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 MRK78 FOC/96 IMAGE 512X512 F502M, 1 9125 S POL0 ------------------------------------------------------------------------------------------------------------------------------------ 12 MRK78 FOC/96 IMAGE 512X512 F502M, 1 9125 S POL60 ------------------------------------------------------------------------------------------------------------------------------------ 13 MRK78 FOC/96 IMAGE 512X512 F502M, 1 9125 S POL120 ------------------------------------------------------------------------------------------------------------------------------------ 5918( 7) - 06/21/96 22:21 - [ 7] Visit: 03 Visit Requirements: CVZ On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 IC5063 FOC/96 IMAGE 512X512 F502M, 1 5265 S POL0 ------------------------------------------------------------------------------------------------------------------------------------ 12 IC5063 FOC/96 IMAGE 512X512 F502M, 1 5265 S POL60 ------------------------------------------------------------------------------------------------------------------------------------ 13 IC5063 FOC/96 IMAGE 512X512 F502M, 1 5265 S POL120 ------------------------------------------------------------------------------------------------------------------------------------ 5918( 7) - 06/21/96 22:21 - [ 8] Summary Form for Proposal 5918 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOC/96 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category AGN ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CVZ ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F502M,POL0 F502M,POL60 F502M,POL120 ------------------------------------------------------------------------------------------------------------------------------------ Target Names MRK3 MRK78 IC5063 ------------------------------------------------------------------------------------------------------------------------------------