\begin{table}%T3
\caption{\label{extin}Extinction.}
%\centering
\par
\begin{tabular}{lc}
\hline
\hline
Diagnostic & $c({\rm H}\beta)$\\
\hline
 H$\alpha$/H$\beta$&0.692\\
 \ion{He}{ii}$\lambda1640$/\ion{He}{ii}$\lambda4686$&0.641\\
 H$\beta$/5~GHz&0.629\\
 H$\beta$/1.4~GHz&0.477\\
 Adopted&0.666\\
\hline
\end{tabular}
\end{table}