\begin{table}%t2 %\centering \par \caption {\label{tab:pnfits}The spectral parameters derived from the \xmm\ EPIC pn observations, with the relative phase coverage. The reported flux is measured in a 0.3--7.0~keV band.} \begin{tabular}{lrrrr} \hline\hline Obs. & 201 & 301 & 401 & 501 \\\hline Start date & 2005-07-27 & 2005-07-29 & 2005-08-02 & 2005-08-06 \\ Start time (UT) & 04:07:27 & 01:36:19 & 05:53:00 & 05:10:42 \\ Obs. duration (s) & 39~234 & 41~030 & 42~504 & 38~170 \\ $\phi$ begin & 0.03 & 0.19 & 0.54 & 0.87 \\ $\phi$ end & 0.07 & 0.23 & 0.58 & 0.91 \\ $N({\rm H})$ ($10^{20}$ cm$^{-2}$) & $4.5\pm0.1$ & $5.2\pm0.2$ & $3.2\pm0.1$ & $5.8\pm0.2$ \\ $T_1$ (keV) & $0.23\pm0.06$ & $0.24\pm0.01$ & $0.29\pm0.01$ & $0.24\pm0.01$\\ $T_2$ (keV) & $0.69\pm0.03$ & $1.14\pm0.1$ & $2.0\pm1.4$ & $0.63\pm0.02$\\ $EM_1$ ($10^{53}$ cm$^{-3}$) & $12.0\pm5.0$ & $18.8\pm6.4$ & $16.0\pm4.2$ & $17.2\pm6.4$\\ $EM_2$ ($10^{53}$ cm$^{-3}$) & $0.96\pm0.42$ & $0.45\pm0.12$ & $0.14\pm0.20$ & $0.83\pm0.42$\\ flux($10^{-12}$ erg cm$^{-2}$ s$^{-1}$) & 1.01 & 0.89 & 0.99 & 0.92\\ O/O$_\odot$ & $0.13\pm0.03$ & $0.08\pm0.02$ & $0.08\pm0.02$ & $0.09\pm0.02$\\ Ne/Ne$_\odot$ & $0.18\pm0.05$ & $0.22\pm0.06$ & $0.16\pm0.03$ & $0.16\pm0.03$\\ Si/Si$_\odot$ & $0.72\pm0.24$ & $0.23\pm0.13$ & $0.40\pm0.13$ & $0.41\pm0.16$\\ Fe/Fe$_\odot$ & $0.45\pm0.13$ & $0.28\pm0.08$ & $0.17\pm0.03$ & $0.32\pm0.08$\\\hline \end{tabular} \end{table}