\begin{table}%t2
\caption{GRB~X-ray afterglow results. For each afterglow, we give the source name, the exposure duration and the net observation duration, together with the results of the spectral and temporal analysis. We quote the absorption (measured at the host redshift or at a value of $z=1$ when the host redshift is unknown) in excess to the galactic absorption. The X-ray absorption excess upper limits are given at the 90\% confidence level. We also indicate the number of detected counts for the source as a proxy of the detection confidence level.}
\label{table_chandra_grating}
\label{table_chandra_imaging}
\label{table_xmm}
\label{table3}
\label{table4}
%\centerline
{\begin{tabular}{ccccccccccc}
\hline\hline
Source  & Flag & Time             & Exposure & Net      & Detected & Temporal & Energy   & Spectral & Excess of & Flux\\
name    &      &since      burst  & duration & duration & count   & decay    & spectral & fit & absorption & \\
        &      &(days)            &  (ksec)  & (ksec)   &number& &index&$\chi_\nu^2$ (d.o.f.)&($10^{21}$ cm$^{-2}$)&erg s$^{-1}$ cm$^{-2}$\\
\hline
\object{GRB~991216}&G&1.52 & 9.8  & 9.8  &1305&  (0.9)        &  0.7 $\pm$ 0.2 & 0.94 (56) & ${<} 9.6$    &1.92 $\pm$ $0.08 \times 10^{-12}$\\
\object{GRB~000210}&I&0.84 & 10.0 & 10.0 &533 & 1.38 $\pm$ 0.03 & 0.9  $\pm$ 0.2 & 1.0 (15)  & 4.7 $\pm$ 1.3& $2.7 \pm 0.2 \times 10^{-13}$\\
\object{GRB~000926}&I&2.67 & 10.0 & 10.0 &307 &1.9  $\pm$ 0.4& 0.7  $\pm$ 0.2 & 1.5 (8)   & ${<} 3.4$      &$1.06 \pm 0.07 \times 10^{-13}$\\
\object{GRB~001025A}&X&1.88& 40.8 & 33.4 &911 & (1.2)        & 1.8  $\pm$ 0.4 & 0.90 (13) & 6 $\pm$ 3     & $2.0 \pm 0.2 \times 10^{-14}$\\
\object{GRB~011030}&I&10.00& 50.0 & 29.6 &248 & 1.9  $\pm$ 0.4& 0.7  $^{+2.1}_{-1.0}$ & 0.1 (6)& ${<} 39$   & $ 5 \pm 1.2 \times 10^{-14}$\\
\object{GRB~011130}&U& 9.77& 30.2 & 30.2 & --&       --    &     --        &  --      &    --        & ${<}0.6\times 10^{-15}$    \\
\object{GRB~011211}&X& 0.50& 33.6 & 33.6 &3589& 2.1 $\pm$ 0.3& 1.3 $\pm$ 0.1 & 1.20 (67) &    ${<}$4.1     & $7.3 \pm 0.2 \times 10^{-14}$\\
\object{GRB~020127}&F& 4.05& 10.0 & 10.0 &26  &       --    &     --        &  --      &    --        & $2.1 \pm 0.5 \times 10^{-14}$\\
                   & &14.53& 10.1 & 10.1 &13  &       --    &     --        &  --      &    --        & $0.6 \pm 0.2 \times 10^{-14}$\\
\object{GRB~020321}&F?&0.43& 50.0 & 32.0 &227 &       --    &     --        &  --      &    --        & see text                 \\
\object{GRB~020322}&X& 0.62& 29.0 & 28.4 &4226& 1.3 $\pm$ 0.3& 1.1  $\pm$ 0.1 & 1.00 (178)& 6.5 $\pm$ 0.8 &$2.11 \pm 0.05 \times 10^{-13}$\\
\object{GRB~020405}&G&1.68 & 51.2 & 51.2 &2086& 1.6 $\pm$ 0.9 &  1.0 $\pm$ 0.2 & 1.24 (75) &5 $\pm$ 2     &$8.9 \pm 0.3 \times 10^{-13}$\\
\object{GRB~020427}&F& 9.06& 13.9 & 13.9 &55  &       --    &     --        &  --      &    --        &  $1.0\pm 0.2 \times 10^{-14}$\\
                   & &17.00& 14.8 & 14.8 &24  &       --    &     --        &  --      &    --        & $0.4 \pm 0.1 \times 10^{-14}$\\
\object{GRB~020531}&U& 5.14& 20.1 & 20.1 & --&       --    &     --        &  --      &    --        & ${<}1.2\times 10^{-15}$    \\
\object{GRB~020813}&G&0.86 & 78.1 & 78.1 &8041& 1.4 $\pm$ 0.2 & 0.83 $\pm$ 0.06& 0.93 (364)& ${<} 2.9$    &$1.63 \pm  0.03  \times 10^{-12}$\\
\object{GRB~021004}&G&0.85 & 88.1 & 88.1 &2656& 1.2 $\pm$ 0.3 & 1.01 $\pm$ 0.07& 1.08 (112)& ${<} 2.8$      &$4.0 \pm  0.2  \times 10^{-13}$\\
\object{GRB~021201}&U& 8.73& 20.0 & 20.0 & --&       --    &     --        &  --      &    --        & ${<}1.2\times 10^{-15}$    \\
\object{GRB~030226}&I&1.54 & 40.0 & 40.0 &371 &2.7  $\pm$ 1.6&0.9 $\pm$ 0.3 & 1.1 (10)&6.6$^{+4.1}_{-3.3}$& $ 3.6 \pm 0.2 \times 10^{-14}$\\
\object{GRB~030328}&G&0.64 & 98.1 & 98.1 &1575& 1.6 $\pm$ 0.3 & 1.1  $\pm$ 0.2 & 0.79 (39) & ${<} 4.0$    &$1.70  \pm  0.08 \times 10^{-13}$\\
\object{GRB~030329}&X&37.04& 244.9& 143.5&639 &    (2)       & 1.0  $\pm$ 0.2 & 0.98 (22) &    ${<}$0.5     & $1.8 \pm 0.2 \times 10^{-14}$\\
\object{GRB~030528}&F& 5.97& 26.1 & 26.1 &44  &       --    &     --        &  --      &    --        & $7.8 \pm 1.3 \times 10^{-15}$\\
                   & &11.80& 20.3 & 20.3 &-- &       --    &     --        &  --      &    --        & ${<} 3.2 \times 10^{-15}$      \\
\object{GRB~030723}&F& 2.14& 24.8 & 24.8 &76  &       --    &     --        &  --      &    --        & $1.4 \pm 0.7 \times 10^{-14}$\\
                   & &12.69& 84.1 & 84.1 &70  &       --    &     --        &  --      &    --        & $2.3 \pm 1.7 \times 10^{e-15}$\\
\object{GRB~031203}&X& 0.26& 112.8& 92.2 &6261& 0.5 $\pm$ 0.1& 0.8  $\pm$ 0.1 & 1.04 (244)& 2.6 $\pm$ 0.7 &$3.95 \pm 0.08 \times 10^{-13}$\\
\object{GRB~031220}&F& 5.62& 40.2 & 40.2 &31  &       --    &     --        &  --      &    --        & $5.2 \pm 1.3 \times 10^{-15}$\\
                   & &28.47& 19.7 & 19.7 &-- &       --    &     --        &  --      &    --        & ${<} 1.5 \times 10^{-15}$       \\
\object{GRB~040106}&X&0.23 & 44.6 & 37.0 &15738&1.4 $\pm$ 0.1& 0.49 $\pm$ 0.04& 1.07 (515)&    ${<}$0.5     & $9.1 \pm 0.2 \times 10^{-13}$\\
\object{GRB~040223}&X& 0.20& 45.2 & 14.3 &1230&0.7 $\pm$ 0.3& 1.6 $\pm$ 0.3 &1.04 (43)&(45--88) $\pm$ 16$^a$& $2.3 \pm 0.2 \times 10^{-13}$\\
\object{GRB~040701}&F& 7.77& 20.0 & 20.0 &68  &       --    &     --        &  --      &    --        & $1.2 \pm 0.2 \times 10^{-14}$ \\
                   & &16.50& 19.0 & 17.5 &39  &       --    &     --        &  --      &    --        & $0.8 \pm 0.2 \times 10^{-14}$ \\
\object{GRB~040812}&F& 5.04& 10.2 & 10.2 &58  &       --    &     --        &  --      &    --        & $1.6 \pm 0.3 \times 10^{-14}$ \\
                   & &10.16& 10.2 & 10.2 &42  &       --    &     --        &  --      &    --        &$ 1.2 \pm 0.2 \times 10^{-14}$ \\
\object{GRB~040827}&X&0.27 & 52.3 & 39.3 &2899& 1.4 $\pm$ 0.3& 1.3  $\pm$ 0.1 & 1.07 (116)& 8.6 $\pm$ 1.5 &$1.25 \pm 0.04 \times 10^{-13}$\\
\hline
\end{tabular}}
\medskip
\par
Note: $^a$ A high galactic density column affect this observation. See Sect. \ref{section_absorp} for details.
\end{table}