\begin{table}%t5
\caption{\ion{O}{vi} column densities.}
\label{tbl_5}
%\centering
\par
\begin{tabular}{lccc}
\hline
\hline
  &\zabs& $N$(\ion{O}{vi}), \cm & Comments\\
\hline
1& 1.8617 & $(3.2\pm0.8)$E13 & $\lambda1037$ blended \\
2& 1.8533 & $(3.0\pm0.8)$E13 & $\lambda1037$ blended \\
3& 1.8073 & $(1.1\pm0.3)$E14 & \\
4& 1.7790 & $(2.5\pm0.8)$E13 & $\lambda1037$ below detection limit \\
5& 1.7744 & $(4.0\pm1.0)$E13 & $\lambda1037$ blended \\
6& 1.7302 & $(4.0\pm1.0)$E13 & \\
7& 1.7154 & $(2.5\pm0.8)$E13 & $\lambda1037$ blended \\
8& 1.6331 & $(7.0\pm1.5)$E13 & $\lambda1037$ blended \\
9& 1.6134 & $(1.3\pm0.3)$E14 & \\ 
10& 1.5955& $(4.2\pm0.8)$E14 & \\
11& 1.5401& $(1.9\pm0.4)$E13 & \\
12& 1.4856& $(1.1\pm0.3)$E14 & $\lambda1037$ blended \\
13& 1.4648& $(1.7\pm0.4)$E14 & \\
14& 1.2910& $(5.0\pm3.0)$E13 & noisy spectrum, {\it S/N} $\sim 3$ \\
15& 1.1896& $(7.0\pm3.0)$E13 & $\lambda1037$ blended \\
16& 1.0778& $(5.0\pm3.0)$E13 & noisy spectrum, {\it S/N} $\sim 3$ \\
\hline
\end{tabular}
\end{table}