\begin{table}%t1
\caption{\label{obslog}Observing log.}
%\centering
\par
\begin{tabular}{lllr}
\hline \hline
Observatory & ObsID  & Obs. date & Exp. time \\
\hline
Chandra & 3733 & 2003-08-10 & 20 ks\\
XMM-Newton & 0144271401 & 2003-10-11 & 7 ks\\
XMM-Newton & 0502370201 & 2007-09-23 & 106 ks\\
XMM-Newton & 0502370301 & 2007-09-24 & 22 ks\\
\hline
\end{tabular}
\end{table}