\begin{table}%t3
\caption{Estimates of the equivalent hydrogen column density $N_{\rm H}$, 
from combined LECS (0.1--4 keV) and MECS (1.6--10 keV) observations with 
various absorption models and chemical abundances.
\label{tab:nh}}
%\begin{center}
 {
\begin{tabular}{cccccc}
\hline\hline
\noalign{\smallskip}
\multicolumn{1}{c}{Model} & \multicolumn{1}{c}{$N_{\rm H}(^*)$} & \multicolumn{1}{c}{$\Gamma$} & \multicolumn{1}{c}{$F_O$} & \multicolumn{1}{c}{$F_{Fe}$} & \multicolumn{1}{c}{$\chi^2_r$}\\
\hline
\texttt{aneb+wabs} & 3.54 $\pm$ 0.01 & 2.124 $\pm$ 0.001 & --            & --            & 0.89 \\
\texttt{angr+bcmc}  & 3.33 $\pm$ 0.01 & 2.124 $\pm$ 0.001 & --            & --            & 0.99 \\
\texttt{angr+bcmc}  & 3.62 $\pm$ 0.04 & 2.125 $\pm$ 0.001 & 0.81 $\pm$ 0.02 & --            & 0.90 \\
\texttt{angr+bcmc}  & 3.63 $\pm$ 0.04 & 2.124 $\pm$ 0.001 & 0.83 $\pm$ 0.03 & 0.87 $\pm$ 0.05 & 0.88 \\
\texttt{angr+bcmc}  & 3.42 $\pm$ 0.02 & 2.123 $\pm$ 0.001 & --            & 0.74 $\pm$ 0.04 & 0.93 \\
\hline 
\end{tabular}}
\parbox{11cm}{
$(^*)$ In units of 10$^{21}$ cm$^{-2}$.}
%\end{center}
\par
\end{table}