\begin{table}%t4
\caption{\label{tablebg}Background evaluation results for the different subcatalogues of cluster members, for both clusters.}
\small%\centerline
 {
\begin{tabular}{c c c c}
\hline\hline
Catalogue & N. objects & Mean BG & rms \\
\hline
   RXCJ~0014.3-3022 (all) & 3698 & 32.37 & 10.31 \\
   RXCJ~0014.3-3022 (red) & 1409 & 9.70 & 4.28 \\
   RXCJ~0014.3-3022 (blue) & 2289 & 21.91 & 6.90 \\
   RXCJ~0014.3-3022 (spec.) & 190 & 1.90 & 3.03 \\
\hline
   RXCJ~2308-0211 (all) & 4109 & 44.72 & 14.74 \\
   RXCJ~2308-0211 (red) & 2361 & 23.26 & 9.52 \\
   RXCJ~2308-0211 (blue) & 1748 & 20.10 & 7.52 \\
   RXCJ~2308-0211 (spec.) & 269 & 1.18 & 5.01 \\
\hline
\end{tabular}}
\medskip
Values are always given in units of number of galaxies per square Mpc.
\end{table}