\begin{table}%t1
\caption{Summary of VLA observations.
\label{obs:tab}}     
\small%\centerline
{        
\begin{tabular}{c c c c c c c c}     
\hline\hline\noalign{\smallskip}
Date & Frequency & \multicolumn{2}{c}{Synthesized beam$^a$} & 
Largest
& Int.\ time & rms & Notes \\ 
 &  & Size & PA & 
angular scale
 & & & \\
     & (GHz) & (arcsec $\times$ arcsec) & (degree) & 
(arcsec)
& (s) & (mJy/beam) & \\
\hline
07/03/2004, 26/02/2004 & 4.75 & $4.8 \times 4.3$ & $-8.2$ & 300 & 1200 & 0.09 & \\ 
07/03/2004 & 8.45 & $2.8 \times 2.6$ & $-20.8$ & 180 & 1800 & 0.08 & \\ 
26/02/2004 & 23 & $1 \times 1$ &  $-40$ & 60 & 7224 & 0.03 & cont. \\
07/03/2004 & 23 & $1 \times 0.9$ &  $-83.7$ & 60 & 434 & 0.05 & line \\
07/03/2004 & 45 & $0.6 \times 0.6$ & $88.6$ & 43 & 17~590$^b$ & 0.08 & \\
\hline
\end{tabular}}
\smallskip
$^a$ Natural 
weighting. $^b$  Fast switching.
\end{table}