\begin{table}%t3
\caption{\label{rgs3_pars}The best-fit parameters of the RGS spectral fitting with the three-component NEI model. $\chi^2/{\rm d.o.f.} = 1.8$ }
%\centering
\small
\begin{tabular}{llll}
\hline\hline
Parameter  & O & Fe-low & Fe-high  \\
\hline\noalign{\smallskip} 
$n_{\rm e}n_{\rm H}~V\; (10^{58},\;\mt{cm}^{-3}$) & $0.50^{+0.08}_{\rm -0.06}$ & $5.6^{+0.2}_{\rm -0.3}$ & $4.8^{+1.2}_{\rm -0.7}$   \\
$kT_{\rm e}$ (keV)                                       & $0.84^{+0.27}_{\rm -0.18}$ & $1.22^{+0.05}_{\rm -0.33}$ & $2.51^{+6.54}_{\rm -0.99}$  \\
$n_{\rm e}t\; (10^{10},\;\mt{s\;cm}^{-3}$)     & $2.3^{+0.8}_{\rm -0.5}$ & $3.0^{+2.3}_{\rm -0.2}$ & $5.2^{+3.4}_{\rm -1.4}$ \\ 
$\sigma_\mt{RGS} (\mt{km\;s}^{-1})$           & \multicolumn{3}{c}{$1873\pm50$} \\
\hline
\end{tabular}
\end{table}