Top: KUV 00311–1938 counts spectrum in different regions of interest: where an Mg II doublet, associated to the host galaxy or to an intervening cold system, is identified at z = 0.506 (left); and where the Ca II H&K absorption features are expected for the tentative redshifts z = 0.61 and z = 0.7635 respectively, as proposed by Piranomonte et al. (2007) and Jones et al. (2009) (right). The expected or measured positions for these spectral features are indicated by the dashed vertical lines. Bottom: UV-to-NIR spectrum of KUV 00311–1938 obtained with X-shooter after flux calibration and telluric corrections. The spectrum is dominated by the non-thermal emission from the nucleus and is well described by a single power law (see Table 9 for details). Only a single extragalactic spectral feature is identified, a doublet corresponding to the absorption by an Mg II system (see the top-left panel of this figure). The Ca II H&K doublet associated with our own Galaxy is also identified and indicated in the figure.