\begin{table}%t4
%\centering
\par
\caption{\label{tb:ml}Parameters of the fits $\log(r_{50}\sigma^2)= aM_r+b$, see Fig.~\ref{fig:ml}.}
\begin{tabular}{llll}
\hline \hline
        & {\it early non-BCGs}     & {\it BCGs}     &   {\it early field}      \\
\hline 
        & C-P04-I        &                & F-P04-E  \\  
\hline
$a$   & $-0.43\pm 0.03$ & $-0.5\pm 0.1$    &   $-0.464\pm 0.005$  \\
$b$   & $-4.2\pm 0.7$   & $-6\pm 2 $       &   $-5.0\pm 0.1$   \\
\hline 
      & C-K07-I        &                   & F-K07-E  \\ 
\hline
$a$   & $-0.40\pm 0.01$ &   $-0.46\pm 0.05$ & $-0.425\pm 0.005$ \\
$b$   & $-3.5\pm 0.3$     & $-5\pm 1$       & $-4.1\pm 0.1$    \\
\hline 
\end{tabular}
\end{table}