Example of a spectral model used to fit the region around the Hβ line. As described in the text, we first subtract an iron template from the spectrum (black line) and then we fit the residual (blue line) with a power-law continuum plus 3 Gaussians describing the narrow Hβ and the two [OIII] lines, plus an additional Gaussian to describe the broad component of the Hβ line. These components are represented by the dashed green lines while the total fit is represented by the red continuous line.