\begin{table}%t8
\caption{\label{tab:xmm}Fit results of X-ray XMM spectra.}
%\centerline
 {\begin{tabular}{ccccccccc}
\hline\hline
\noalign{\smallskip}
Inst. & Model & $N_{\rm H}$ & $\Gamma$ & Norm & KT & Norm BB & $N_{\rm H}^{z}$ & $\chi^{2}\rm (d.o.f.)$\\
(1) & (2) & (3) & (4) & (5) & (6) & (7) & (8) & (9)\\
\hline
PN-M1-M2 & ab*pl & 2.0 & $\rm 1.15^{1.16}_{1.14}$ & $\rm 4.5^{4.6}_{4.4}$ & --  & -- & -- & 1110(1013)\\
PN-M1-M2 & ab*pl & $\rm 4.5^{5.1}_{3.9}$ & $\rm 1.24^{1.26}_{1.21}$ & $\rm 5.0^{5.1}_{4.9}$ & --  & -- & -- & 1050(1012)\\
PN-M1-M2 & ab(ab$_{z}$*pl) & 2.0 & $\rm 1.22^{1.24}_{1.20}$ & $\rm 4.8^{4.9}_{4.7}$ & --  & -- & $\rm 4.8^{5.9}_{3.8}$ & 1047(1012)\\
PN-M1-M2 & ab(pl+bb) & 2.0 & $\rm 1.08^{1.09}_{1.06}$ & $\rm 3.9^{4.0}_{3.7}$ & $\rm 0.35^{0.40}_{0.32}$  & $\rm 2.4^{3.1}_{1.9}$ & -- & 1057(1011)\\
\hline
\end{tabular}}
\par
\smallskip
Explanation of columns: (1)~=~instruments; (2)~=~fit model; (3)~=~column density (units of 10$^{20}$~cm$^{-2}$), (4)~=~spectral index; (5)~=~normalization (units of 
10$^{-4}$~ph~keV$^{-1}$~cm$^{-2}$); (6)~=~photon temperature; (7)~=~blackbody normalization; (8)~=~absorption parameter at the source (units of 10$^{21}$~cm$^{-2}$); (9)~=~statistical fit result.
\end{table}