\begin{table}%t1
%\centering
\par
\caption{Models of the PN~spectrum of \ob, taking into account absorption.  {\tt po}: power law. {\tt bb}: black body. {\tt diskbb}: multi black body (Mitsuda et~al.\ \cite{M84}).  {\tt brems}: bremsstrahlung. The number of degrees of freedom is~161. 
The column density is expressed in units of 10$^{22}$~cm$^{-2}$. The flux ($F_{\rm X}$) and luminosity ($L_{\rm X}$) corrected for absorption are expressed in 10$^{-11}$~erg~cm$^{-2}$~s$^{-1}$ and 10$^{35}$~erg~s$^{-1}$, respectively. 
The luminosity is calculated assuming $d=8$~kpc.}\label{tab:fit}
\begin{tabular}{@{}cccccccc@{}}
\hline\hline
%\smallskip
Model  &   ${\cal N}_{\rm H}$ &  $\Gamma$ or $kT$ & $\chi^{2}_{\rm red}$ & $F_{\rm X}$ & $L_{\rm X}$ & $F_{\rm X}$ & $L_{\rm X}$ \\
%       &  &  & & \multicolumn{2}{c}{\hline} & \multicolumn{2}{c}{\hline} \\
       &  &  & & \multicolumn{2}{c}{2--10~keV} & \multicolumn{2}{c}{0.5--10~keV} \\
\hline
{\tt po}     &  $\rm 14.1^{+1.6}_{-1.4}$  & $\rm 1.65^{+0.17}_{-0.16}$ & 0.87 & 1.4 & 1.0 & 2.1 & 1.5 \\
{\tt bb}     &  $7.3\pm0.9$  & $1.9\pm0.1$      &1.08&   1.0 & 0.7  & 1.0 & 0.7    \\
{\tt diskbb} &  $11.0\pm1.0$  & $3.7\pm0.5$     & 0.93 & 1.2 & 0.9 & 1.4 & 1.0 \\
{\tt brems} &   $13.6\pm1.2$  & $\rm 22^{+40}_{-15}$  & 0.88 & 1.3 & 0.9 & 1.8 & 1.3 \\
\hline
\end{tabular}
%\vspace*{-0.3cm}
\end{table}