Observed (black) and synthetic (red) intensity and circular polarization profiles for AD Leo in all considered wavelength regions. The synthetic profiles were calculated using two components: one non-magnetic (“photospheric”) and one magnetic (“spot”) atmosphere model (Allard et al. 2001). Fits to Stokes I and V spectra for each atom and molecule were obtained individually (see Sect. 4.2), but all the parameters were obtained simultaneously: the photosphere and spot temperatures, the magnetic field strength, the spot filling factor for the intensity f_I, and the circular polarization f_V. In three regions Stokes V was not fitted because of lower signal to noise in this particular wavelength region and observation,while in other regions the signal is stronger, despite the fact that it looks like noise because the region contains many lines.