Upper panel: flux-calibrated spectrum of J2310 in the region of the Lyα emission with the two continua used to normalize it. Lower panels: fit of the observed transitions for the proximate DLA in the spectrum of J2310. In each panel, the observed spectrum is shown in blue, the error in red, and the Voigt fit in green. The top panel shows the fit of the H I Lyα velocity profile. The red mark indicates the redshift z = 5.938646, which is also the zero-point of the velocity scale in all other panels.