\begin{table}%t2
\caption{Observed and modeled quantities.}
\label{ta:table2}
%\centerline
{\begin{tabular}{lrr}
\hline \hline \noalign{\medskip}
                             &Observed        &Model\\
\hline\noalign{\medskip}
{\em Single dish}\/:         &                &\\
%\sp Line ratio               &\about 9        &\about 4\\
\sp Velocity range$^{a}$ (\kms)&270 $\pm$ 20     &\about 280\\
\hline\noalign{\medskip}
{\em EVN+MERLIN}\/:          &                &\\
\sp $\tau\sub{North}^{b}$   &$3.85\pm0.34$   &3.58\\
\sp $\tau\sub{South}$        &$4.30\pm0.12$   &3.80\\
\sp $\tau\sub{East}$         &$2.66\pm0.33$   &1.20\\
\sp $\tau\sub{West}$         &$2.26\pm0.21$   &0.69\\
\hline\noalign{\medskip}
{\em Global VLBI}\/:         &                &\\
\sp $\tau\sub{South}$        &$>$6.21         &7.28\\
\sp {\it FWHM} of peak spot (\kms) &\about30        &30\\
\hline  
\end{tabular}}
$^{a}$ Velocity width of the 1667 feature at 10\% of the peak
 flux density.\\
$^{b}$ The effective opacities are $\tau\sub{North} = {\rm
ln}({\rm LCR}\sub{North})$, etc.
\end{table}