\begin{table}%t3
  \caption{\label{tab3}The XIS 1--10 keV spectra of the six time-intervals.}
%\centerline
 {\begin{tabular}{lcccc}
\hline\hline
\noalign{\smallskip}
Interval & $\Gamma $ & log $\xi$\tablefootmark{a} & $N_{\rm W}$\tablefootmark{b}   & $F_{\rm 2-10}$\tablefootmark{c}\\
\hline
1 & $1.50\pm 0.07$ & $1.6\pm 0.1$ & $1.6\pm 0.2$ & 4.8 \\
2 & $1.67\pm 0.06$ & $1.7\pm 0.1$ & $1.2\pm 0.2$ & 5.2 \\
3 & $1.32\pm 0.08$ & $1.3\pm 0.1$ & $2.0\pm 0.2$ & 3.3 \\
4 & $1.08\pm 0.06$ & $1.0\pm 0.1$ & $2.4\pm 0.2$ & 2.6 \\
5 & $1.16\pm 0.06$ & $1.0\pm 0.1$ & $2.4\pm 0.2$ & 4.9 \\
6 & $1.58\pm 0.06$ & $1.6\pm 0.1$ & $1.3\pm 0.2$ & 5.6 \\[5pt]
$\Gamma $ & -- & $1.47\pm 0.04$ & $1.40\pm 0.04$ \\
log $\xi$\tablefootmark{a}  & $1.5\pm 0.1$ & --  & $1.2\pm 0.1$ \\
$N_{\rm W}$\tablefootmark{b}  & $2.2\pm 0.3$ & $2.2\pm 0.1$ & --  \\[5pt]
$\chi^2$/d.o.f. & 671.8/676 & 707.2/676 & 698.1/676 \\
\hline
\end{tabular}}
\tablefoot {Results of fitting a single warm absorber model to the 1--10~keV XIS spectra from the six time-intervals are presented. One of the three
    parameters, $\Gamma $, $\xi $, and $N_{\rm W}$, is a free
    parameter when fitting the six spectra, besides the normalizations of
    the power-law continuum. The other two are tied together between the
    spectra and reported below. Observed \mbox{2--10}~keV flux is also given.
\tablefoottext{a}{In unit of erg~s$^{-1}$~cm.}
\tablefoottext{b}{In unit of $10^{22}$~cm$^{-2}$.}
\tablefoottext{c}{The 2--10~keV flux in unit of $10^{-12}$~erg~cm$^{-2}$~s$^{-1}$.}}
\end{table}