Abstract

The findings of a nine-orbit calibration plan carried out during HST Cycle 15, to fully determine the NICMOS camera 2 (2.0 !m) polarization calibration to high accuracy, are reported. Recently Ueta et al. and Batcheldor et al. have suggested that NICMOS possesses a residual instrumental polarization at a level of 1.2%–1.5%. This would completely inhibit the data reduction in a number of GO programs, and hamper the ability of the instrument to perform high-accuracy polarimetry. We obtained polarimetric calibration observations of three polarimetric standards at three spacecraft roll angles separated by !60°. Combined with archival data, these observations were used to characterize the residual instrumental polarization in order for NICMOS to reach its full potential of accurate imaging polarimetry at p " 1%. Using these data, we place an 0.6% upper limit on the instrumental polarization and calculate values of the parallel transmission coefficients that reproduce the ground-based results for the polarimetric standards. The uncertainties associated with the parallel transmission coefficients, a result of the photometric repeatability of the observations, are seen to dominate the accuracy of p and ". However, the updated coefficients do allow imaging polarimetry of targets with p " 1:0% at an accuracy of !0:6% and !15°. This work enables a new caliber of science with HST.

Publication Date

2009

Comments

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type

Article

Department, Program, or Center

Chester F. Carlson Center for Imaging Science (COS)

Campus

RIT – Main Campus

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