\begin{table}%t1
%\centering
\par
\caption{Observation log for the data used in this analysis.\label{tab1} }
\newcommand{\m}{\hphantom{$-$}}
\newcommand{\cc}[1]{\multicolumn{1}{c}{#1}}
\begin{tabular}{@{}ccrrrr}
\hline \hline
Revolution & \multicolumn{1}{c}{Start-Stop time} & \multicolumn{4}{c}{Exposure (ks)}\\ 
                  & (MJD)                  & JEM-X & ISGRI & PICsIT &SPI \\
\hline
39   &  52677.2--52679.8  & 149.3  & 142.3 & -- &--\\
40   &  52680.2--52681.6  & 122.6  & 56.0  & 106.5  &--\\
41   &  52683.2--52685.8  &  --  & -- & 204.0   &-- \\
42   &  52686.4--52688.2  & 75.4   & 61.6  & -- &138.5\\
43   &  52689.6--52691.7  & --   & 30.7  & -- & 154.9\\
44   &  52692.2--52694.4  & --  & 9.8  &-- &146.9\\
45   &  52695.2--52696.7  & --  & 2.1 & -- &27.4\\
102  &  52866.3--52868.1  & --  & 37.9 &  -- &78.0\\
103  &  52868.6--52868.8  &     & 21.6 & -- &--\\
\hline
\multicolumn{2}{l}{Total}  & 347.3   & 362.0 & 310.5  & 545.7\\                  
\hline
\end{tabular}
\end{table}