\begin{table}%t4
\caption{\label{taball}GRB los available from the literature.}
%\centerline
{\begin{tabular}{cccccccc}
\hline
\hline
GRB &  $z_{\rm GRB}$  & $z_{\rm start}$ & $z_{\rm end}$ & $z_{\rm abs}$ & $W_{\rm r}(2796)$ & 
$\Delta v_{\rm ej}$   & Reference $^\dagger$\\
    &                 &  &   &   &  (\AA) & (km/s) & \\
\hline
991216& 1.022 & 0.366 & 1.002 &0.770$^a$  & $4.0 \pm 0.8^b$  & $\sim$40~000 & 3\\
& &&  & 0.803  & $6.1 \pm 0.7^b$ &  $\sim$34~000&  \\
000926 & 2.038 & 0.616 & 2.008 &  &  &  & 1\\
010222 & 1.477 & 0.430 & 1.452  & 0.927  & $1.00 \pm 0.14$ &$\sim$74~000& 2\\
       & &&  & 1.156  & $2.49 \pm 0.08$ & $\sim$41~000 &  \\
011211 & 2.142 & 0.366 & 1.932 &  &  &   & 3 \\
020405 & 0.695 & 0.366 & 0.678 & 0.472 & $1.1 \pm 0.3$ &$\sim$42~000 & 4 \\
020813 & 1.255 & 0.366 & 1.232  & 1.224 & $1.67 \pm 0.02$ & $\sim$4000  & 5 \\
030226 & 1.986 & 0.366 & 1.956 & & & & 6 \\
030323 & 3.372 & 0.824 & 1.646  & & & & 7 \\
030328& 1.522 & 0.366& 1.497  & & & & 14 \\
030429 & 2.66 & 0.620 & 1.861  & 0.8418    & $3.3\pm0.4^b$ & $\sim$179~000 & 15 \\
050505 & 4.275 & 1.414 & 2.27  & 1.695    & $1.98$ & $\sim$176~000  & 8 \\
& &&  & 2.265 & $1.74 $ & $\sim$134~000 & \\
050908 & 3.35 & 0.814 & 2.27  & 1.548  & $1.336 \pm 0.107$ & $\sim$147~000  & 9\\
051111 & 1.55 & 0.488 & 1.524  & 1.190  & $1.599 \pm 0.007$ & $\sim$45~000  & 9\\
060206 & 4.048 & 1.210 & 2.27  & 2.26  & $1.60$ & $\sim$123~000 & 10, 13\\
060526 & 3.221 & 0.836 & 2.27  &  & &   & 11\\
071003 & 1.604 & 0.366 & 1.578  & 0.372  & $2.48 \pm 0.20$ & $\sim$170~000  & 12\\
\hline
\end{tabular}}
\par
\medskip
 $^\dagger$ 1: \cite{Castro2003}; 2: \cite{Mirabal2002}; 3: \cite{Vreeswijk2006a}; 5: \cite{Barth2003}; 4: \cite{Masetti2003};   6: \cite{Klose2004}; 7: \cite{Vreeswijk2004}; 8: \cite{Berger2006}; 9: \cite{Prochter2006a}; 10: \cite{Chen2009};   11: \cite{Thoene2008}; 12: \cite{Perley2008}; 13: \cite{Hao2007}; 14: \cite{Maiorano2006}; 15: \cite{Jakobsson2004}.
$^a$The very low resolution of the GRB~991216 spectrum makes the $z$=0.77 absorber identification uncertain.
$^b$The $W_{\rm r}$ values refer to the total equivalent width of the MgII doublet.
\end{table}