\begin{table}%t1
%\centering
\par
\caption{\label{obs}Observation log, duration total, (PN/MOS filtered).}
{\begin{tabular}{lccc}\hline\hline
Target & Obs. mode &  Obs. time  & Dur. (ks)\\\hline
XX Cha & FF/med.~F. & 2005-09-02T03:34--03/16:03 & 125 (70/85) \\
\hline
\end{tabular}
}
\end{table}