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Data Analysis for the SOLIS Vector SpectromagnetographThe National Solar Observatory's SOLIS Vector Spectromagnetograph (VSM), which will produce three or more full-disk maps of the Sun's photospheric vector magnetic field every day for at least one solar magnetic cycle, is in the final stages of assembly. Initial observations, including cross-calibration with the current NASA/NSO spectromagnetograph (SPM) will soon be carried out at a test site in Tucson. This paper discusses data analysis techniques for reducing the raw data, calculation of line-of-sight magnetograms and both quick-look and high-precision inference of vector fields from Stokes spectral profiles. Existing SPM algorithms, suitably modified to accomodate the cameras, scanning pattern, and polarization calibration optics for the VSM, will be used to "clean" the raw data and to process line-of-sight, magnetograms. A recent. version of the High Altitude Observatory Milne-Eddington (HAO-ME) inversion code (Skumanich and Lites; 1987, 11)J 322, p. 473) will he used for high-precision vector fields since the algorithm has been extensively tested, is well understood, and is fast enough to complete data analysis within 24 hours of data acquisition. The simplified inversion algorithm of Auer, Heasley. arid House (1977, Sol. Phys. 55, p. 47) forms the initial guess for this version of the HAO-ME code and will be used for quick-look vector analysis of VSM data since its performance on simulated Stokes profiles is better than other candidate methods. Improvements (e.g., principal components analysis or neural networks) are under consideration and will be straightforward to implement. However, current resources are sufficient to store the original Stokes profiles only long enough for high-precision analysis. Retrospective reduction of Stokes data with improved methods will not be possible, and modifications will only be introduced when the advantages of doing so are compelling enough to justify discontinuity in the long-term data stream.
Document ID
20020067637
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Jones, Harrison P.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Harvey, John W.
(National Solar Observatory Tucson, AZ United States)
Oegerle, William
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Subject Category
Astronomy
Meeting Information
Meeting: International Astronomical Union Colloquium 188: Magnetic Coupling on the Solar Atmosphere
Location: Naples
Country: Italy
Start Date: May 30, 2002
End Date: June 18, 2002
Sponsors: International Astronomical Union
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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