\begin{table}%t2
\caption{\label{agns}Main characteristics of the extragalactic sources.}
%\centerline
{
\begin{tabular}{lcccc}
\hline\hline
Source name 	&Distance &1$''$ equiv.    &Size of IR emitting region &IR luminosity\\ 
                &Mpc      &pc           &arcsec                     &$L$sol (log~10)\\ \hline
NGC 1068	&15       &73           &$<$2.0                     &11.30 $^{{a}}$\\  
NGC 7172	&35       &168          &$<$2.5                     &10.45 $^{{b}}$ \\ 
IRAS 19254--7245	&240      &1160         &                           &12.06 $^{{b}}$ \\ 
NGC 5506	&24       &117          &                           &10.36 $^{{a}}$ \\\hline
\end{tabular}}
\smallskip
\begin{list}{}{}
\item
$^a$ Rigopoulou et~al.  (\cite{1999AJ....118.2625R}); $^b$ Bonatto \& Pastoriza (\cite{1997ApJ...486..132B}).
\end{list}
\end{table}