Top: zones where individual spectra of S(1) line, have been extracted, superimposed on parameters maps (the same as in Fig. 2). Bottom: for each zone the normalized average spectrum (black) is superimposed on the respective pixel by pixel 1D model (solid blue) and regularized 3D model (solid red). The gray line reproduces another solution of the regularized 3D fitting. Both solutions have close values of χ2 (1.15 and 1.49, respectively), but the red model fits the observations much better.