\begin{table}%t1
%\centering
\par
\caption{Journal of observations.}\label{t1}
\begin{tabular}{cccc}
\hline\hline
Date & UT & JD-2400000 & No. of obs.  \\
\hline
 26 July 1997 &  6:14--10:37  & 50~655.762 & 153 \\
 11 August 1998 & 2:47--5:53  & 51~036.636 & 100 \\
 13 August 1998 & 3:04--7:10  & 51~038.632 & 145 \\
\hline
\end{tabular}
\end{table}