\begin{table}%t5
\caption{DLA and sub-DLA systems where no candidate emission lines
  are found and 3$\sigma$~upper limits for the line fluxes.  Fluxes
  are in units of $10^{-17}$~\ecs.}
  \label{tab:hiz_non_det}
%\centering
\small
\begin{tabular}{lll}
 \hline \hline
QSO & $z_{{\rm abs}}$ & $f_{{\rm lim}} (3\sigma)$\\
   \hline
Q0953+4749 & 4.244 & 2.5\\
Q1451+1223 & 2.256 & 4.0\\
Q1802+5616 & 3.554 & 4.0\\
Q1802+5616 & 3.811 & 2.2\\
Q2155+1358 & 3.565 & 3.5\\
Q2233+131  & 2.551 & 4.8\\
\hline
\end{tabular}
\end{table}