\begin{table}%t2
%\centering
\par
\caption
{\label{tab_ext:diff_coord_2}Median and mean separation (and standard
deviation) between 2MASS and IRAS coordinates and between 2MASS and
MSX~coordinates.}
\begin{tabular}[t]{lrcccc}
\hline\hline\noalign{\smallskip}
 & $N$ & $\Delta\alpha$ & $\Delta\alpha$ ($\sigma_{\Delta\alpha}$) &
 $\Delta\delta$ & $\Delta\delta$ ($\sigma_{\Delta\delta}$) \\ & &
 median & mean & median & mean \\
\hline\noalign{\smallskip}\noalign{\smallskip}
2MASS--IRAS& 59 & 3.8\arcsec & 7.6\arcsec~ (8.7\arcsec) & 1.7\arcsec & 2.0\arcsec~ (2.4\arcsec) \\
2MASS--MSX & 49 & 0.9\arcsec & 1.2\arcsec~ (1.1\arcsec) & 1.0\arcsec & 1.4\arcsec~ (1.3\arcsec) \\
\hline
\end{tabular} 
\end{table}