SDSS spectrum of J0234−08 (X-HESS 7) at z = 0.992 (in gold) compared to the composite QSO’s template of Vanden Berk et al. (2001). The template (in black) is extinguished according to the SMC extinction law by Prevot et al. (1984), with progressively increasing values of E(B − V). The value of E(B − V) that minimises the distance between the reddened template (in purple) and the observed SDSS spectrum at wavelengths of λ_obs < 8000 Å in the observer frame, corresponds to our estimate of the internal reddening of the source. J0234−08 has the largest E(B − V) among our sources, i.e. E(B − V) = 0.33.