\begin{table}%t3
   %\centering
\par
   \caption{\label{widemagvaries}Photometric redshift accuracy in the W1 and D1 fields for
     a range of limiting magnitudes.}
      \begin{tabular}{c c c c}
     % \multicolumn{4}{c}{}\\
      \multicolumn{4}{c}{W1}\\
       \hline
       \hline
       $i'_{\rm AB} < $ & $S/N$  & $\sigma_{\Delta z/(1+z_{\rm s})}$ & $\eta$ (\%)  \\
       \hline
       20.5 & 64 & 0.025 & 1.12 \\
       21.0 & 60 & 0.026 & 1.57 \\
       21.5 & 52 & 0.029 & 1.39 \\
       22.0 & 43 & 0.032 & 2.25 \\
       22.5 & 33 & 0.037 & 2.81 \\
       23.0 & 24 & 0.043 & 4.91 \\
       23.5 & 16 & 0.048 & 7.63 \\
       24.0 & 11 & 0.053 & 10.13 \\
       \hline
    \end{tabular}
\par
  \begin{tabular}{c c c c}
     %\multicolumn{4}{c}{}\\
      \multicolumn{4}{c}{D1}\\
       \hline
       \hline
       $i'_{\rm AB} < $ & $S/N$ & $\sigma_{\Delta z/(1+z_{\rm s})}$ & $\eta$ (\%)  \\
       \hline
       20.5 & 72 & 0.030 & 0.54 \\
       21.0 & 72 & 0.027 & 1.17 \\
       21.5 & 72 & 0.025 & 1.32 \\
       22.0 & 68 & 0.026 & 1.30 \\
       22.5 & 68 & 0.026 & 1.82 \\
       23.0 & 60 & 0.026 & 2.11 \\
       23.5 & 54 & 0.027 & 2.59 \\
       24.0 & 43 & 0.028 & 3.57 \\
       \hline
    \end{tabular}
\par
 \end{table}