\begin{table}%t1
\caption{\label{table_rxte_obs}RXTE \psrtar\ observation summary.}
\par
%\centerline
{\small
\begin{tabular}{c c c c c}
\hline\hline
Obs. id.    & Date begin & Date End   & MJD         & Exposure\tablefootmark{a}\\
            &            &            &             &   (ks)  \\
\hline
20259       & 30-09-1997 & 30-09-1997 & 50~721--50~722 & 16.96   \\
\vspace{-2.5mm}\\
60130       & 17-08-2001 & 19-08-2001 & 52~138--52~141 & 80.35   \\
\vspace{-2.5mm}\\
70089       & 10-03-2002 & 23-04-2003 & 52~343--52~752 & 268.95  \\
\vspace{-2.5mm}\\
90080       & 28-02-2004 & 03-03-2005 & 53~063--53~432 & 243.23  \\
\vspace{-2.5mm}\\
91063       & 12-03-2005 & 18-03-2006 & 53~441--53~813 & 328.74  \\
\hline
\end{tabular}}
\tablefoot{\tablefoottext{a}{Screened (GTI) exposure for PCA unit-2.}}
\end{table}