\begin{table}%t4 
\caption{\label{obsinfo}Information on X-ray data.}
 \small%\centering
\par
\begin{tabular}{ccccccc}
\hline\hline\noalign{\smallskip}
 Name & Filter & \multicolumn{3}{c}{$t_{\rm exp}$ (ks)} & $n_{\rm H}$ (\rm $10^{20}$ cm$^{-2}$)\\
          & &  MOS1 & MOS2 & pn\\
\hline\noalign{\smallskip}
Abell~222 &    Thin1 & 11.814 & 18.005 & 10.226 & 2.26\\
Abell~223 &    Thin1 & 23.479 & 26.069 & 10.612 & 2.26\\
\hline	  
\end{tabular}
\end{table}