Recently, it has been shown that NICMOS possesses an instrumental polarization at a level of 1.2%. This completely inhibits the data reduction in a number of previous GO programs, and hampers the ability of the instrument to perform high accuracy polarimetry. In all, 90 orbits of HST data are affected, with potentially many more in Cycle 15. We propose to obtain high signal to noise observations of three polarimetric standards at the cardinal roll angles of the NICMOS polarizers for both NIC1 and NIC2. These observations are designed to fully characterize the instrumental polarization in order for NICMOS to reach its full potential by enabling high accuracy polarimetry of sources with polarizations around 1%. The residual polarization will also be determined as a function of position and spectral energy distribution. Our group will rapidly turn around the required data products and produce reports and software for the accurate representation of the instrumental polarization. These items will be presented to STScI and for dissemination among the wider astronomical community.

We will observe three standard stars (two polarized, one unpolarized), at three discrete roll angles,using the three polarizers of NIC1 (POL0S, POL120S, POL240S) and the three polarizers of NIC2 (POL0L, POL120L, POL240L). In NIC2, each target will be observed in each quadrant of the array. NIC1 observations will be placed at a position defined by the lack of grot and relatively shallow flat field gradient. Each NIC2 exposure sequence will follow a spiral dither pattern with at least N+1/2 pixel offsets, where N is sufficiently large so that at least the second airy ring from the PSF at each position does not overlap. Observing the standard stars at the three cardinal roll angles of the polarizers removes the dependence of the measured Stokes parameters on the relative transmission of each of the filters and, at the same time, any dependence of the instrumental polarization on detector sensitivity to polarized light (since the analyzer detector system is fixed for a given polarizer). By doing this one removes degrees of freedom in the transfer Muller matrix. Combining two polarized stars with largely different polarimetric orientations and an additional unpolarized star similarly observed, will enable us to accurately measure the instrumental polarization. These observations will allow us to comprehensively investigate how the NICMOS polarization depends on field position, camera choice and the color of the target. We will be able to derive matrix co-efficients capable of giving accurate polarimetry in targets that have an intrinsic polarization of around 1%. Essential for the success of this calibration proposal is the observation of each standard star at three separate roll angles, hence three separate epochs. The requested roll angles have been chosen in order to maximize the science return from the optimum number of orbits. They must be separated by 120D+/-3D in each epoch. We also require the collection of high signal to noise dark frames. It is essential that we count the incoming photons with as high an accuracy as possible in order to get confident polarimetry. These dark frames will also provide the institute with a good comparison for the synthetic darks. NIC1 Observations: We will adjust the current pos-targs for these observations at a later date. The most appropriate position on this array for polarimetry has yet to be identified. SAA Impact: This is a fundamental calibration to enable new HST science. As a consequence we must have SAA non-impacted orbits. Darks: We have scheduled darks at the end of each exposure sequence. The APT-OP does not accurately represent how these darks may be taken. If acquiring the needed SAA non-impacted darks proves impossible with the darks defined this way, our PC is free to "break up" the darks into separate visits PROVIDED that the darks remain SAA non-impacted and that they are acquired within 24 hours of the observations. Hold: We have placed all observations on hold for the time being. Concerns have very recently been raised about the characteristics of our chosen polarimetric standards. There is a possibility that the targets will be changed after the phase II deadline. AGN/QUASARS 0 true 0.0 false false false false false false AVAILABLE STAR B3-B5 V-IV The co-oridinates for this object are the ones supplied by the GSC2 Hipparcos/Tycho web interface at http://galex.stsci.edu/gsc2/GSC2webform.aspx We would like to note that there has been some discrepancies regarding SIMBAD ICRS, VTT and GSC2 co-ordinates, and that the differences (5.5") will significantly impact this calibration proposal if they are not clearly resolved. STScI is aware of this problem. J = 9.34+/-0.02(2MASS), K = 9.13+/-0.02(2MASS) WKK-F-7 VR84C J2000 00 00 0.0000 +00 00 0.00 J2000 STAR K III-I The co-oridinates for this object are the ones supplied by the GSC2 Hipparcos/Tycho web interface at http://galex.stsci.edu/gsc2/GSC2webform.aspx We would like to note that there has been some discrepancies regarding SIMBAD ICRS, VTT and GSC2 co-ordinates, and that the differences (5.5") will significantly impact this calibration proposal if they are not clearly resolved. STScI is aware of this problem. J = 9.648+/-0.02(2MASS), K = 8.677+/-0.02(2MASS) VSS-VIII-13 R-CRA-DC-NO.13 J2000 00 00 0.0000 +00 00 0.00 J2000 STAR A4-A9 V-IV The co-oridinates for this object are the ones supplied by the GSC2 Hipparcos/Tycho web interface at http://galex.stsci.edu/gsc2/GSC2webform.aspx We would like to note that there has been some discrepancies regarding SIMBAD ICRS, VTT and GSC2 co-ordinates, and that the differences (5.5") will significantly impact this calibration proposal if they are not clearly resolved. STScI is aware of this problem. J = 8.80+/-0.03(2MASS), K = 8.72+/-0.02(2MASS) J2000 00 00 0.0000 +00 00 0.00 J2000 NIC1 Imaging No Yes NIC2 Imaging No Yes NIC1 Imaging No Yes NIC2 Imaging No Yes NIC1 Imaging No Yes NIC2 Imaging No Yes (Tic-Visit :proposal-id 10839 :visit-id "01" :proposal-version -1 :trans-version "20060619" :date "10-Oct-2006 16:48:38.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 1407952 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10839 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10839 :visit-id "01" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2926 :al-overhead-at-end 0 :internal-dur-at-end 2449 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3355 :pcs-gap 0 ) false 1 0 Orientation: <Orient From:> can also be <by: 297> <to: 303> as the effective orientation of the polarizers can be +/-180D. (Tic-Visit :proposal-id 10839 :visit-id "02" :proposal-version -1 :trans-version "20060619" :date "10-Oct-2006 16:52:36.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 1407952 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10839 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10839 :visit-id "02" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2926 :al-overhead-at-end 0 :internal-dur-at-end 2449 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3355 :pcs-gap 0 ) false 1 0 Orientation: <Orient From:> can also be <by: 57> <to: 63> as the effective orientation of the polarizers can be +/-180D. (Tic-Visit :proposal-id 10839 :visit-id "03" :proposal-version -1 :trans-version "20060619" :date "10-Oct-2006 16:54:40.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 1407952 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10839 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10839 :visit-id "03" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2926 :al-overhead-at-end 0 :internal-dur-at-end 2449 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3355 :pcs-gap 0 ) false 1 0 There may be some difficulty with getting the required orientation seperation. From inspection of the available roll angles it would seem most appropriate to use 42D, 342D and 282D for visits 4, 5 and 6 respectively. The same format for visits 1, 2, and 3 could be used, but we have placed the suggested orientations in the APT for use with the visit planner. (Tic-Visit :proposal-id 10839 :visit-id "04" :proposal-version -1 :trans-version "20060322" :date "19-May-2006 15:13:47.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 1575760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10839 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10839 :visit-id "04" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2677 :al-overhead-at-end 0 :internal-dur-at-end 2531 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3159 :pcs-gap 0 ) false 1 0 There may be some difficulty with getting the required orientation seperation. From inspection of the available roll angles it would seem most appropriate to use 42D, 342D and 282D for visits 4, 5 and 6 respectively. The same format for visits 1, 2, and 3 could be used, but we have placed the suggested orientations in the APT for use with the visit planner. (Tic-Visit :proposal-id 10839 :visit-id "05" :proposal-version -1 :trans-version "20060322" :date "19-May-2006 15:34:39.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 1575760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10839 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10839 :visit-id "05" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2677 :al-overhead-at-end 0 :internal-dur-at-end 2531 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3159 :pcs-gap 0 ) false 1 0 There may be some difficulty with getting the required orientation seperation. From inspection of the available roll angles it would seem most appropriate to use 42D, 342D and 282D for visits 4, 5 and 6 respectively. The same format for visits 1, 2, and 3 could be used, but we have placed the suggested orientations in the APT for use with the visit planner. (Tic-Visit :proposal-id 10839 :visit-id "06" :proposal-version -1 :trans-version "20060322" :date "19-May-2006 15:36:12.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 1575760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10839 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10839 :visit-id "06" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2677 :al-overhead-at-end 0 :internal-dur-at-end 2531 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3159 :pcs-gap 0 ) false 1 0 The position of this object introduces tight constraints on possible roll angles according to the Visit Planner. Not all angles +/-180D area available, and the roll angle window is limited, thus we have placed rigid acceptable orientations in this case. There is room to shift the orientation zero point (140D) slightly if necessary. (Tic-Visit :proposal-id 10839 :visit-id "07" :proposal-version -1 :trans-version "20060322" :date "19-May-2006 15:15:20.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 1575760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10839 :visit-id "07" :obset-id "07" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10839 :visit-id "07" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2677 :al-overhead-at-end 0 :internal-dur-at-end 2531 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3152 :pcs-gap 0 ) false 1 0 The position of this object introduces tight constraints on possible roll angles according to the Visit Planner. Not all angles +/-180D area available, and the roll angle window is limited, thus we have placed rigid acceptable orientations in this case. There is room to shift the orientation zero point (140D) slightly if necessary. (Tic-Visit :proposal-id 10839 :visit-id "08" :proposal-version -1 :trans-version "20060322" :date "19-May-2006 15:39:01.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 1575760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10839 :visit-id "08" :obset-id "08" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10839 :visit-id "08" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2677 :al-overhead-at-end 0 :internal-dur-at-end 2531 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3152 :pcs-gap 0 ) false 1 0 The position of this object introduces tight constraints on possible roll angles according to the Visit Planner. Not all angles +/-180D area available, and the roll angle window is limited, thus we have placed rigid acceptable orientations in this case. There is room to shift the orientation zero point (140D) slightly if necessary. (Tic-Visit :proposal-id 10839 :visit-id "09" :proposal-version -1 :trans-version "20060322" :date "19-May-2006 15:40:46.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 1575760 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10839 :visit-id "09" :obset-id "09" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10839 :visit-id "09" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2677 :al-overhead-at-end 0 :internal-dur-at-end 2531 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3152 :pcs-gap 0 ) false 1 0