Top: parts of the X-shooter counts spectrum of BZB J0505+0415 in the VIS arm after a median filtering with a 3-pixel window. The absorption features are identified as corresponding to the Mg and CaI+FeI (left) and Na I D (right) lines for z = 0.424. The expected positions are indicated by the dashed vertical lines. Bottom: UV-to-NIR spectrum of BZB J0505+0415 (in black) along with the result of our modelling (in red), based on a fit of a galaxy template (in green) and a power law (see Sect. 3 for details, and Table 8 for results). In the inset, a zoom of the absorption lines corresponding to Ca II H&K doublet at z = 0.424, identified after flux calibration and telluric correction, is shown along with a local fit (in red).