\begin{table}%t5
%\centering
\par
\caption {\label{tab:ibis}Log of IBIS/ISGRI observations.}
\begin{tabular}{cccc}
\hline\hline
Rev. & Start date (UTC)& End date (UTC) & Exp (s) \\
\hline
0493 & 2006-10-26 23:31:06 & 2006-10-29 04:19:28 & 180~423\\
0494 & 2006-10-29 22:36:24 & 2006-11-01 12:51:01 & 202~377\\
0549 & 2007-04-12 23:33:26 & 2007-04-15 03:02:26 & 170~054\\
0550 & 2007-04-15 17:04:49 & 2007-04-18 01:32:37 & 188~714\\
0552 & 2007-04-22 07:17:30 & 2007-02-24 01:23:05 & 136~084\\
0558 & 2007-05-09 11:34:04 & 2007-05-10 21:03:40 & 115~482\\ \hline
\end{tabular}
\end{table}