M 1 Calibration No calibration Modelbased calibration Databased
M 1 Calibration ● ● No calibration Model-based calibration Data-based calibration Entrance aperture calibration optics
M 1 Calibration ● No calibration – ● ● ● Off-diagonal elements ~1%. Can't meet science req Model-based calibration Data-based calibration Entrance aperture calibration optics
M 1 Calibration ● ● No calibration Model-based calibration Data-based calibration Entrance aperture calibration optics
M 1 Calibration ● ● No calibration Model-based calibration – – – ● ● Mirror imperfections, irregularities Properties change with time Importance (? ? ? ) Data-based calibration Entrance aperture calibration optics
M 1 Calibration ● ● No calibration Model-based calibration (? ) Data-based calibration Entrance aperture calibration optics
M 1 Calibration ● ● ● No calibration Model-based calibration (? ) Data-based calibration – – Reliability? Profile asymmetries arise due to physical effects ● ● Velocity/Field gradients Line-of-sight integration Departures from linear Zeeman regime Entrance aperture calibration optics
M 1 Calibration ● ● No calibration Model-based calibration (? ) Data-based calibration Entrance aperture calibration optics
M 1 Calibration ● ● ● No calibration Model-based calibration (? ) Data-based calibration – Some things that can be relied upon ● ● – HOWEVER ● ● – ● Orientation of continuum scattering polarization Orientation of sky scattering polarization Degree of polarization is unknown No source of circular polarization Standard stars (? ) Entrance aperture calibration optics
M 1 Calibration ● ● No calibration Model-based calibration (? ) Data-based calibration (? ? ) Entrance aperture calibration optics
M 1 Calibration ● ● No calibration Model-based calibration (? ) Data-based calibration (? ? ) Entrance aperture calibration optics – – Can't build a 4 -m array of polarizers An alternative approach: Non-collimated incidence
M 1 Calibration ● ● No calibration Model-based calibration (? ) Data-based calibration (? ? ) Entrance aperture calibration optics – – Can't build a 4 -m array of polarizers An alternative approach: Non-collimated incidence
M 1 Calibration
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