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Paper: The Diffraction Limited Spectro-Polarimeter
Volume: 358, Solar Polarization 4
Page: 201
Authors: Sankarasubramanian, K.; Lites, B.; Gullixson, C.; Elmore, D.; Hegwer, S.; Streander, K.; Rimmele, T.; Fletcher, S.; Gregory, S.; Sigwarth, M.
Abstract: The Diffraction Limited Spectro-Polarimeter (DLSP) is a collaboration between the National Solar Observatory (NSO) and the High Altitude Observatory (HAO) to provide a stable instrument for precision measurements of solar vector magnetic fields at high angular resolution. The DLSP is integrated with the new high-order Adaptive Optics (HOAO) system at the Dunn Solar Telescope (DST) and provides Stokes spectra of the Fe I 630nm lines approaching the 0.″2 diffraction limit of the DST. It is configured as a fixed, well-calibrated instrument that may be used simultaneously with G-band (1nm bandpass) and a CaK imagers (0.1nm bandpass). The 2K×2K G-band imager allows fast frame selection and includes a burst mode for speckle imaging. The setup of DLSP and its imagers require only about 10 min of preparation before start of observations. This fixed setup facilitates standardized data reduction. The DLSP permits observations with 0.″09 sampling in high resolution mode. In wide-field mode, the 0.″27 sampling allows one to map regions about 3′ on a side. The achieved continuum S/N is 500 (1500) in high resolution (wide-field) mode for a 4 s integration. It is possible to achieve higher S/N by integrating longer. Data reduction routines are now available in IDL for post-observation processing, and parallel analysis routines in FORTRAN77 are being developed to allow “on-the-fly” data reduction and inversion.
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