\begin{table}%t3
\label{zz}
\caption{\label{tab3}Results of the spectral analysis of GRB~with known redshift.}
%\centerline
{
\begin{tabular}{cccccc}
\hline\hline
GRB~   &Redshift & $N_{\rm H}$ Gal.  & $N_{\rm H}$ obs.$^*$   & $\chi^2_{\rm red}$ & $N_{\rm H}$
DLA ($90\%$)\\
       & (ref.)  &$10^{20}\cmdue$& $10^{20}\cmdue$    & (d.o.f.)	          & $10^{20}\cmdue$  \\
\hline
050126 &1.29 (1) & 5.3       &$<$$9.4          $    & 1.0 (10)         & 0.8 (6.4)\\
050315 &1.95 (2) & 4.3	     &$\rm 83.7^{+19.7}_{-17.4}$ &  1.4 (43)      & 1.4 (5.7)\\
050318 &1.44 (3) & 2.8       &$\rm 11.3^{+10.7}_{-8.9}$ & 0.6 (39)        & 0.9 (12.9)\\
050319 &3.24 (4) & 1.1       &$\rm 38.6^{+18.0}_{-16.0}$& 1.4 (29)        & 3.6 (447)\\
050401 &2.90 (5) & 4.8       &$\rm 366^{+47}_{-46}$    & 1.1 (294)      & 3.0 (272)\\
050408 &1.24 (6) & 1.7       &$\rm 134^{+34}_{-28}$    & 1.0 (45)       & 0.8 (4.7)\\
\hline
980703 &0.97     & 5.8       &$\rm 290^{+71}_{-27}$    &            & 0.6 (1.7) \\ 
990123 &1.60     & 2.1       &$\rm 30^{+70}_{-20}$   	&            & 1.1 (23.1) \\ 
990510 &1.63     & 9.4       &$\rm 160^{+19}_{-13}$    &            & 1.1(25.1)\\ 
000210 &0.85     & 2.5       &$\rm 50^{+10}_{-10}$    &             & 0.0 (0.0) \\
000214 &0.47     &5.8        &$<$$2.7$            &            & 0.0 (0.0) \\
000926 &2.07     & 2.7       &$\rm 40^{+35}_{-25 }$    &            & 1.6 (73.9)\\
010222 &1.48     & 1.6       &$\rm 120^{+70}_{-60 }$   &             & 1.0 (15.1)\\
001025a&1.48     & 6.1       &$\rm 66^{+30}_{-30}$    &             & 1.0 (15.1) \\
020322 &1.80     & 4.6       &$\rm 130^{+20}_{-20}$    &            & 1.3 (40.7)\\
020405 &0.70     & 4.3       &$\rm 47^{+37}_{-37}$     &            & 0.0 (0.0) \\
020813 &1.25     &7.5        &$<$$36.5$           &            & 0.8 (5.0)\\
021004 &2.33     &4.3        &$<$$34$             &            & 2.0 (118)\\
030226 &1.98     & 1.6       &$\rm 68^{+41}_{-33}$     &            & 1.5 (60.8)\\
030227 &3.90     & 22        &$\rm 680^{+18}_{-38}$    &            & 5.2 (649)\\
030328 &1.52     &4.3        &$<$$44.3$           &            & 1.0 (17.3)\\
\hline
\end{tabular}}
\smallskip
$^*$ Column density values have been computed at the GRB~redshift.\\
References: (1) Berger et~al. (\cite{Berger2005}); (2) Kelson \&  Berger (\cite{Kelson2005}); (3) Berger
\& Mulchaey (\cite{Berger2005m}); (4) Fynbo et~al. (\cite{Fynbo2005}); (5) Fynbo et~al. (\cite{Fynbo2005e}); (6) Berger et~al.  (\cite{Berger2005e}). 
Values in the second part of the table are from Stratta et~al. (\cite{Stratta2004}), De~Luca
et~al. (\cite{Luca2005}) and Gendre et~al. (\cite{Gendre2005}).
\end{table}