\begin{table}%t1
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\caption{Journal of XMM-Newton observations of the \object{M~31} core.\label{journ}}
\begin{tabular}{lllllll}
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\hline\hline
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Observation & Date & MJD&  Exp  & Filter\\
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\hline
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x1 &  25/06/00 (rev0100)& 51720& 34 ks& Medium \\
x2 & 27/12/00 (rev0193)& 51906 & 13 ks&  Medium\\
x3 & 29/06/01 (rev0285)& 52089& 56 ks &Medium & \\
x4 & 06/01/02 (rev0381)& 52280 & 61 ks&  Thin\\
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\hline
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\end{tabular}
\end{table}