\begin{table}%t3
\caption{\label{pn-fits-a}Results from the two-temperature model fits to the \mbox{EPIC-pn} spectra
           -- the parameters allowed to vary with time. Fluxes are given in
	   units of \oergcm{-13} and emission measures EM in 10$^{58}$~cm$^{-3}$.}
\small%\centering
\par
\begin{tabular}{lccc}
\hline\hline
\multicolumn{1}{l}{Parameter} &
\multicolumn{1}{c}{Rev. 626} &
\multicolumn{1}{c}{Rev. 244} &
\multicolumn{1}{c}{Rev. 21/22}\\
\multicolumn{1}{l}{} &
\multicolumn{1}{c}{May 2003} &
\multicolumn{1}{c}{Apr. 2001} &
\multicolumn{1}{c}{Jan. 2000}\\
 \hline 
 \multicolumn{4}{l}{Model A} \\ 
 NEI $kT$ (keV)			  & $\rm 3.22_{-0.49}^{+0.53}$ & $\rm 1.76_{-0.34}^{+0.68}$  & $\rm 2.10_{-0.29}^{+0.35}$ \\ 
 NEI EM                 	  & $\rm 1.00_{-0.15}^{+0.08}$ & $\rm 0.69_{-0.15}^{+0.18}$  & $\rm 0.43_{-0.06}^{+0.06}$ \\ 
 RAYMOND $kT$ (keV)		  & $\rm 0.30_{-0.02}^{+0.02}$ & $\rm 0.24_{-0.02}^{+0.02}$  & $\rm 0.24_{-0.02}^{+0.02}$ \\ 
 RAYMOND EM                       & $\rm 16.0_{-3.7}^{+3.0}$   & $\rm 5.1_{-1.4}^{+1.1}$     & $\rm 3.2_{-0.9}^{+0.7}$    \\
 Flux (0.5--2.0 keV)		  & 8.10		   & 2.77		     & 1.75		      \\
 Flux (3.0--10.0 keV)		  & 1.77		   & 0.43		     & 0.39		      \\
 Flux (0.2--10.0 keV)		  & 11.4		   & 3.82		     & 2.59		      \\
\noalign{\smallskip}\hline\noalign{\smallskip}
 \multicolumn{4}{l}{Model B} \\
 NEI $kT$ (keV)			  & $\rm 3.11_{-0.45}^{+0.63}$ & $\rm 1.65_{-0.18}^{+0.42}$  & $\rm 2.01_{-0.28}^{+0.17}$ \\ 
 NEI EM                   	  & $\rm 1.03_{-0.14}^{+0.14}$ & $\rm 0.74_{-0.15}^{+0.25}$  & $\rm 0.45_{-0.05}^{+0.07}$ \\ 
 MEKAL $kT$ (keV) 		  & $\rm 0.31_{-0.02}^{+0.02}$ & $\rm 0.25_{-0.02}^{+0.03}$  & $\rm 0.24_{-0.02}^{+0.01}$ \\ 
 MEKAL EM                         & $\rm 13.4_{-1.3}^{+1.4}$   & $\rm 4.0_{-0.9}^{+0.9}$     & $\rm 2.6_{-0.6}^{+0.6}$    \\
 Flux (0.5--2.0 keV)		  & 8.11		   & 2.78		     & 1.75		      \\
 Flux (3.0--10.0 keV)		  & 1.74		   & 0.40		     & 0.38		      \\
 Flux (0.2--10.0 keV)		  & 11.4		   & 3.79		     & 2.58		      \\
\hline
\end{tabular}
\end{table}