\begin{table}%t2
\caption{\label{flux}The total flux ($2{-}10$~keV) as measured adopting the baseline model (described further in the text).}
%\centering
\par
\begin{tabular}{cc}
\hline
\hline
\textbf{Observation} & \textbf{Flux 2--10~keV} \\
& in units of $10^{-11}$ erg cm$^{-2}$ s$^{-2}$ \\
\hline
{\it ASCA}  1994 & $9.24\pm0.26$ \\
{\it ASCA}  1996 & $7.45\pm0.21$ \\
BeppoSAX 1998 & $9.30\pm0.07$ \\
{\it Chandra} 2000 & $9.66\pm0.11$ \\
XMM 05/2001 & $8.08\pm0.01$ \\
XMM 12/2001 & $7.12\pm0.02$ \\
\hline
\end{tabular}
\end{table}