Spectra of object A (upper panels) and object B (lower panels) obtained with X-shooter. Flat-field correction, bias and sky subtraction, and flux calibration were performed on both spectra. Vertical dotted lines highlight the main emission features which allow to identify object A as a QSO. Similar features are totally absent in the spectrum of object B. (Color legend – Blue: UVB arm; black: VIS arm; red: NIR arm.)