\begin{table}%t4
\caption{\label{fit_neb_ab}Fit parameters for a H/He/C/N/O NLTE atmosphere;  $F_{\rm X}$ is the unabsorbed source flux in the 0.1--0.5~keV energy band.}
%\centering
\small 
\begin{tabular}{cccccccc}
 \hline \hline
\noalign{\smallskip}
$\log{g}$&$\chi^{2}_{\rm red}$/d.o.f. &$N_{\rm H}$                                             & $T$                 & $R$ & $M$ & $F_{\rm X}$ & $F_{\rm bol}$\\
          (cm s$^{-2}$)&          & ($10^{20}~ \mbox{cm}^{-2}$) &($10^{5}$ K) & ($10^{10}$ cm) & ($10^{33}$ g)& ($10^{-11}$ $\frac{\rm erg}{\rm cm^{2}~ s}$) &($10^{-10}$ $\frac{\rm erg}{\rm cm^{2}~ s})$\\
\noalign{\smallskip} \hline
 6.0	&1.17/124	& $2.8\pm0.4$ & $1.54\pm0.01$ & $1.3\pm0.1$ & $2.4\pm0.2$ & $2.96$ & $1.51$ \\\noalign{\smallskip}
  6.5	&1.11/124	& $3.2^{\rm +0.3}_{-0.5}$ & $1.54^{\rm +0.01}_{-0.02}$ & $1.5\pm0.1$ & $10.1\pm0.6$ & $3.5$ & $2.0$ \\\noalign{\smallskip}
 7.0	&1.09/124	& $3.0\pm0.5$ & $1.54^{\rm +0.01}_{-0.02}$ & $1.3\pm0.1$ & $25.1^{\rm +2.2}_{-1.3}$ & $2.73$ & $1.56$ \\[2pt]
\hline
\end{tabular}
\end{table}