\begin{table}%t6
   \caption{Count rate (in counts per second) and flux level in the~\mbox{0.5--2.0}~keV band for all known X-ray observations of XZ Tau.
     Flux in units of $10^{-13}$ \ecms.}  
%%%\centering
\par
    \begin{tabular}{ccll}
\hline  \hline
Date & Instr. & Rate & Flux \\\hline
1981--31--01 & IPC  & 0.017 & 1.82 \\
1994--23--02 & ASCA (SIS) & 0.06  & 15 \\
1996--12--31 & PSPC & 0.023 & 1.13 \\
1997--02--10 & PSPC & 0.021 & 1.05 \\
1997--05--31 & HRI & 0.0132 & 1.69 \\
1999--12--14 & HRI & 0.0162 & 2.07 \\
2000--09--09 & XMM (pn) & 0.13 & 2.9 \\
2001--07--23 & Chandra & 0.024 & 0.96 \\
\hline
    \end{tabular}
    \label{tab:xzsto}
\end{table}