Fast Inversion of Spectral Lines Using Principal Components Analysis. II. Inversion of Real Stokes Data
The principal components analysis (PCA) technique is used to develop an extremely fast and stable Stokes inversion code, suitable for application to large data sets from instruments that operate under standard conditions. This paper provides some tips on reducing the dimensionality of the problem, which are then used to develop a practical implementation of PCA for the automatic analysis of Stokes profiles. The resulting code is tested using real spectropolarimetric observations of the pair of Fe I lines at 6302 Å at a sunspot.