Community Spectro-Polarimetric Analysis Center (CSAC) Overview

The Community Spectro-Polarimetric Analysis Center (CSAC) is a National Center for Atmospheric Research (NCAR) Strategic Initiative that provides a suite of community resource tools for analysis of the precision polarization data for remote sensing of magnetic fields in the solar atmosphere. The tools provided range from those used for data reduction/calibration through those which extract measures of the magnetic field vector (and associated thermodynamic properties) from the observed data and finally to those which allow the user to display and manipulate the derived vector magnetic fields.

CSAC has contributed data reduction/calibration software to two ground-based spectro-polarimetric instruments available to the community: the Diffraction-Limited Spectro-Polarimeter (DLSP) at the National Solar Observatory (NSO), and the Spectro-Polarimeter at the Swedish Solar Observatory on La Palma, Canary Islands, Spain. Importantly, this software has been adapted to process data from the Spectro-Polarimeter on the Hinode satellite. CSAC also has now completed the workhorse MERLIN data analysis package that performs the critical process of extraction of the magnetic field vector from the observed polarization spectra. This is the first such package that is composed for distribution to the community: the software is portable, carefully documented, computationally efficient, and modular so that it may be adapted for other purposes. MERLIN will be used to provide bulk processing of data from the Hinode Spectro-Polarimeter data, thereby providing the first large-scale database of precision measures of the solar magnetic field vector to a wider community that is not highly versed in the complexity of analysis of spectro-polarimetric data.

Other components of CSAC include the exploration of advanced techniques for data analysis and display. A new, fast analysis technique based on artificial neural networks has been completed and tested as an initialization of the MERLIN least-squares fitting routine. Although this technique gives accurate results for a high percentage of solar conditions, it still does not provide the best guess possible that has been achieved by the standard, but much slower, genetic algorithm initialization. In the coming year CSAC will implement a code (LILIA) that extracts a more detailed physical characterization of the magnetic structure of the solar atmosphere: adapt the AZimuth AMbigiuty (AZAM) utility for display of results from MERLIN and assist in resolving an inherent ambiguity in the inferred azimuth of the magnetic field; and begin implementation of inversion procedures for the analysis of chromospheric magnetic fields, e.g. from the Prominence Magnetometer.