\begin{table}%t1 \caption{\label{obs}Log of the \xmm\ observations of \sm.} %\centerline {\small \begin{tabular}{ccccccc} \hline\hline ID & Date & Duration & Net exposure & Off~axis angle & Count rate & Tot. counts\\ & & (ks) & (ks) & (arcmin) & (cts~s$^{-1}$) & \\ \hline \noalign{\smallskip} 0501470101 & 2007/06/04 & 31.8 & 7.7 & 5.58 & 0.400 & 3100\\ 0601210101 & 2009/05/14 & 26.7 & 16.54 & 7.20 & 0.309 & 5167 \\ 0601210501 & 2009/09/25 & 48.7 & 32.3 & 14.06 & 0.153 & 5442 \\ \hline \end{tabular}} \tablefoot{All the quantities refer to the EPIC pn camera.} \end{table}