\begin{table}%t1
\caption{\label{tab1}Log of the {\it Chandra} and {\it XMM-Newton} observation used 
in this paper.}
\small%\centering
\par
\begin{tabular}{cllcc}
\hline
\hline
\multicolumn{1}{c}{Spacecraft} & \multicolumn{1}{c}{Object} & 
\multicolumn{1}{c}{Start day} & Start time & On-source \\
 & & & \multicolumn{1}{c}{(UT)} & time (ks) \\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
{\it XMM-Newton} & 4U~1700+24  & 11 Aug. 2002 & 15:38:22 & 5.96 \\
{\it XMM-Newton} & 4U~1700+24  & 07 Mar. 2003 & 01:08:08 & 5.02 \\
{\it XMM-Newton} & 4U~1700+24  & 09 Mar. 2003 & 01:03:49 & 8.97 \\
{\it XMM-Newton} & 4U~1700+24  & 13 Aug. 2003 & 15:23:12 & 13.6 \\
{\it Chandra}    & 4U~1700+24  & 23 Apr. 2005 & 02:45:03 & 1.15 \\
{\it Chandra}    & 4U~1954+319 & 18 Jan. 2006 & 20:24:30 & 1.18 \\
\hline
\end{tabular}
\end{table}