\begin{table}%t2
 \caption{XRT observation log of GRB~070311.}
 \label{tab:logXRT}
 \small%\centerline
{
 \begin{tabular}{ccccrrr}
 \hline
 \hline
Sequence & Obs mode & Start time (UT) &  End time (UT) & Exposure & Start time$^{{a}}$ & 
            End time$^{{a}}$ \\
         &          &                 &       &   (s)    & (s)   &    (s)\\ 
 \hline
00020052001 &  PC & 2007-03-11 03:49:34 &  2007-03-11 17:08:03  &18~780 &   7004 &  54~913\\
00020052002 &  PC & 2007-03-13 00:49:40 &  2007-03-13 13:46:56  & 9697 & 169~010 & 215~646\\
00020052003 &  PC & 2007-03-14 00:49:36 &  2007-03-14 13:53:56  & 9465 & 255~406 & 302~466\\
00020052004 &  PC & 2007-03-15 00:47:36 &  2007-03-15 14:01:54  & 9954 & 341~686 & 389~344\\
00020052005 &  PC & 2007-03-16 01:06:34 &  2007-03-16 23:41:55  & 9028 & 429~224 & 510~545\\
00020052006 &  PC & 2007-03-17 01:08:59 &  2007-03-17 22:21:55  &14~574 & 515~769 & 592~145\\
00020052007 &  PC & 2007-03-17 23:45:20 &  2007-03-18 22:32:56  & 6283 & 597~150 & 679~206\\
00020052008 &  PC & 2007-03-19 00:04:45 &  2007-03-19 22:38:54  & 3711 & 684~715 & 765~964\\
  \hline
  \end{tabular}}
  \medskip
  $^{{a}}$ Since {\rm INTEGRAL} trigger time.
\end{table}