\begin{table}%t1
 %\centering
\par
      \caption{\label{tab:all}The sample of clusters.}
\par
        \small
         \begin{tabular}{llllllllccclll}
            \hline\hline
\multicolumn{1}{c}{Name}&
\multicolumn{3}{c}{$\alpha (2000)$}&
\multicolumn{3}{c}{$\delta (2000)$}&
\multicolumn{1}{c}{$z$}&
\multicolumn{1}{c}{\#Frames}&
\multicolumn{1}{c}{Area (Mpc$^2$)}&
\multicolumn{1}{c}{Seeing~($''$)}\\
\hline\noalign{\smallskip}
{A~2658} & 23 & 44 & 49 & --12 & 17 & 39 & 0.185 & 1 & 0.3055   & 0.70 \\
{A~1643} & 12 & 55 & 54 & +44 & 05 & 12 & 0.198 & 2 & 0.6810  & 0.55 \\
{A~1878} & 14 & 12 & 52 & +29 & 14 & 28 & 0.220 & 2 &  0.7894 & 0.70  \\
{A~2111} & 15 & 39 & 40 & +34 & 25 & 27 & 0.229 & 2 & 0.8030  & 0.70 \\
{A~1952} & 14 & 41 & 03 & +28 & 37 & 00 & 0.248 & 2 & 0.7989  & 0.55--0.80\\
\hline
         \end{tabular} 
   \end{table}