\begin{table}%t1
\caption {Observational parameters of the radio data.\label{table:obs_radio}}
%\centering
\par
\begin{tabular}{clll}
\hline\hline
$\lambda$  & Instrument  & Beam & Noise\\
(cm) & and configuration & (\s$ \times $\s)  & (mJy/b)\\
\hline
3.6 & ATCA (6B), VLA (D) & 1.5~$\times$~0.8  & 0.05  \\
6  & ATCA (6B), VLA (DnC),SD &2.9~$\times$~1.6& 0.07  \\
20  &  VLA (A, CnB) & 2.5~$\times$~1.2  & 0.12 \\
\hline
\end{tabular}
\end{table}