\begin{table}%t3
 \caption{\label{tab:RMsource}RM values for sources B and C.}
\par
%\centerline
{\small 
\begin{tabular}{lcccc}
\hline\hline
Name&   $\langle RM_{\rm obs} \rangle$ & $\langle RM_{\rm crf} \rangle$     & Fit error (average)& N of beams\\
    &   rad/m$^2$  &    rad/m$^2$ & rad/m$^2$     &\\
\hline
Source B & $-130$  & $-312$ &1 & 3\\
Source C &  85   & 204  &1 & 3 \\
\hline
\end{tabular}}\smallskip
\par
Column~1: Source name ; Col 2: observed $\langle RM\rangle$;
Col 3: $\langle RM\rangle$ in the cluster rest   frame; 
Col. 4: fit error; Col 5: number of sampled beams.
\end{table}