\begin{table}%t1
\caption{\label{tbl_obs}Observations on September 27, 2007.}
\par
%\centering
\small
\begin{tabular}{lllll} 
\hline\hline
Instrument & Filter & Duration (s) & UT start time & UT stop time \\
\hline
PN   & Medium & 34~457 & 02:40:19 & 12:14:36 \\
MOS1 & Medium & 36~019 & 02:18:22 & 12:18:41 \\
MOS2 & Medium & 36~026 & 02:18:21 & 12:18:47 \\
\hline
\end{tabular}
\end{table}