\begin{table}%t3
\caption{\label{tab:rm1}Rotation measures values of the observed sources.}               
%\centerline
 {        
\begin{tabular}{c c c c c c c}    
\hline
\hline
\noalign{\smallskip}
Source    & Projected distance & n. of beams &$\langle \rm RM\rangle$    &$\sigma_{\rm RM,obs}$& Err$_{\rm fit}$& $\sigma_{\rm RM}$ \\
          &   kpc    &     & rad/m$^2$   & rad/m$^2$       &  rad/m$^2$ &  rad/m$^2$  \\    
\hline            
5C4.85    &   51   &  35   &--256~$\pm$~50  &   303    & 46     &   299~$\pm$~36     \\
5C4.81    &   124  &  56   &--120~$\pm$~22   &   166   & 48     &   159~$\pm~$17        \\ 
5C4.74    &   372  &  10   &372~$\pm$~51   &   154    & 44     &   148~$\pm$~41      \\ 
5C4.114   &   532  &  16   & 51~$\pm$~4    &    16    &  2     &    16~$\pm$~3     \\ 
5C4.127   &   919  &   7   & 21~$\pm$~30    &    65   & 36     &    54~$\pm$~26         \\
5C4.42    &  1250  &  33   & 6~$\pm$~12     &    56   & 43     &    36~$\pm$~11           \\ 
5C4.152   &  1489  &   4   & 32~$\pm$~27    &    37   & 28     &    24~$\pm$~21    \\
\hline
\end{tabular}}
\par
\tablefoot {
{Column~1: source name Col. 2: source
                   projected distance from the X-ray cluster center;} 
{Col. 3:  number of beams over which RMs are computed;} 
{Col. 4: mean value of the observed RM distribution;} 
{Col. 5: dispersion of the observed RM distribution; } 
{Col. 6: median of the RM fit error; Col.~7: dispersion of the RM distribution after noise deconvolution.}}
\par
\end{table}