STARLIGHT fit for the spectrum of the X-shaped source J1424+2637. The plot shows the observed spectrum (top black line), the modeled spectrum (second red line, displaced from observed spectrum), the AGN continuum (blue line), and the residual spectrum (bottom green line). Note that the residual spectrum contains narrow and (in some objects) broad emission lines. Properties of these lines are measured separately (see Sect. 3.2).