\begin{table}%t2
%\centering
\par
\caption{\label{tab-reg}Extraction regions for the \xmm\ spectral analysis of the source.}
\begin{tabular}{lccc}
\hline\hline
\noalign{\smallskip}
\multicolumn{1}{c}{Ring} &
\multicolumn{2}{c}{Radius (arcsec)} &
\multicolumn{1}{c}{No. of Obs.}\\
\multicolumn{1}{c}{No.} &
\multicolumn{1}{c}{inner} & 
\multicolumn{1}{c}{outer}\\
\hline
1 & 30  & 57 & 2\\
2 & 57  & 84 & 2\\
3 & 84  & 138 & 3\\
4 & 138 & 192 & 3\\
5 & 192 & 246 & 1\\
6 & 246 & 300 & 2\\
\hline
\end{tabular}
\end{table}