\begin{table}%t2
%\centering
\par
\caption{Observation log.}
\begin{tabular}{rcccc}
      \hline
      \hline
      \noalign{\smallskip}
 Date     & UT    & $T_{\rm exp}$/s   & $T_{\rm cycl}$/s & Duration/s\\
      \noalign{\smallskip}
      \hline
      \noalign{\smallskip}
22.05.2004 & 20:17 & 60           & 68          & 17~799\\
23.05.2004 & 20:20 & 60           & 68          & 17~485\\
24.05.2004 & 20:18 & 60           & 68          & 17~312\\
 \noalign{\smallskip}
      \hline
\end{tabular}\label{tab_obs}
\end{table}