| The 2005 HST Calibration Workshop (2008) | |||||||||||||
Abstract | |||||||||||||
| Abstract. NICMOS cameras 1 and 2 (with ∼ 43 and ∼ 76 mas/pixel, respectively) each carry a set of three polarizing elements to provide high sensitivity observations of linearly polarized light. The polarizers are bandpass limited and provide diffractionlimited imaging in camera 1 at 0.8- 1.3µm, and in camera 2 at 1.9-2.1µm. The NICMOS design specified the intra-camera primary axis angles of the polarizers to be differentially offset by 120 ◦ , and with identical polarizing efficiency and transmittance. While this ideal concept was not strictly achieved, accurate polarimetry in both cameras, over their full (11 ′ ′ and ∼ 19.2 ′ ′ square) fields of view was enabled through ground and on-orbit calibration of the as-built and HST-integrated systems. The Cycle 7 & 7N calibration program enabled and demonstrated excellent imaging polarimetric performance with uncertainties in measured polarization fractions ≤ 1%. After the installation of the NICMOS Cooling System (NCS), the polarimetric calibration was re-established in Cycle 11, resulting in systemic performance comparable to (or better than) Cycle 7 & 7N. | |||||||||||||
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