\begin{table}%t3
  \caption{\label{tab3}Observed binary properties.}
  %\centering
$$
  \begin{tabular}{lr@{~$\pm$~}lr@{~$\pm$~}lr@{~$\pm$~}lr@{~$\pm$~}lc}
    \hline\hline\\[-2ex]
    &
    \multicolumn{2}{c}{$\Delta i'$} &
    \multicolumn{2}{c}{$\Delta z'$} &
    \multicolumn{2}{c}{Sep} &
    \multicolumn{2}{c}{PA} &
    Date \\
    Name &
    \multicolumn{2}{c}{[mag]} &
    \multicolumn{2}{c}{[mag]} &
    \multicolumn{2}{c}{[\arcsec]} &
    \multicolumn{2}{c}{[$^\circ$]} &
    (UT) \\[0.5ex]
    \hline\\[-2ex]
    WASP-2 & 4.095&0.025 & 3.626&0.022 & 0.757&0.001 & 104.7&0.3 & Nov. 2007\\
    TrES-2 & 3.661&0.016 & 3.429&0.010 & 1.089&0.008 & 135.5&0.1 & May 2007\\
    TrES-4 & 4.560&0.017 & 4.232&0.025 & 1.555&0.005 & 359.8&0.1 & Jun. 2008\\[0.5ex]
  \hline
  \end{tabular}
  $$
\end{table}