Spectra of the z _ { em } = 4.12 quasar Q 0000 - 2619 have been obtained in the range \lambda \lambda = 4880 - 8115 Åwith a resolution of 13 kms ^ { -1 } and signal–to–noise ratio of s / n = 15 - 60 per resolution element .
The list of the identified absorption lines is given together with their fitted column densities and Doppler widths .
The mode of the distribution of the Doppler parameters for the Ly \alpha lines is \simeq 25 kms ^ { -1 } .
The fraction of lines with 10 < b < 20 kms ^ { -1 } is 17 % .
The Doppler values derived from uncontaminated Ly \beta lines are smaller than those obtained from the corresponding Ly \alpha lines , indicating the contribution of non saturated , non resolved components in the Ly \alpha profiles .

The integrated UV background estimated from the proximity effect is found to be J \sim 7 \times 10 ^ { -22 } erg s ^ { -1 } cm ^ { -2 } Hz ^ { -1 } sr ^ { -1 } .
This value is consistent with previous estimates obtained at a lower z , implying no appreciable redshift evolution of the UVB up to z = 4 .

13 metal systems are identified , five of which previously unknown .
The analysis of the associated metal systems suggests abundances generally below the solar value with an average [ C/H ] \sim - 0.5 .
This value is about one order of magnitude higher than that found in intervening systems at about the same redshift .

The analysis of the intervening metal line systems has revealed in particular the presence of three optically thin systems with \log N _ { HI } \sim 15 showing associated CIV and SiIV absorptions .
In order to make the observed column densities consistent with [ Si/C ] ratios lower than 10 times the solar value , it is necessary to assume a large jump in the spectrum of the ionizing UV background beyond the HeII edge ( J _ { 912 } / J _ { 228 } \raise - 2.0 pt \hbox { \hbox to 0.0 pt { \hbox { $ \sim$ } } \raise 5.0 pt% \hbox { $ > $ } } 1000 ) .
This result , if confirmed in other spectra at the same redshift is suggestive of a possible dominance of a stellar ionizing emissivity over the declining quasar one at z > 3 .

Key words : Galaxies : formation of – general : intergalactic medium – quasars : Q 0000 - 2619