\begin{table}%t3
\caption{\label{duptab}Duplicated detections from regions of overlap between fields.}
%\centering
\par
\begin{tabular}{cccc}
\hline \hline
\noalign{\smallskip}
 Field & Field & \# of Duplicates & Velocity offset\tablefootmark{a}\\
\hline\\[-3mm]
 2 & 5 & 3 & 18 km s$^{-1}$  \\
 4 & 5 & 10 & --24 km s$^{-1}$ \\
 7 & 8 & 3 & --55~km s$^{-1}$ \\
 4 & 7 & 1& 22 km s$^{-1}$ \\
 8 & phantom PNe & 16 &47 km s$^{-1}$\\
\hline
\end{tabular}
\tablefoot{\tablefoottext{a}{The velocity offset is the amount necessary to add to the velocities  from the first column in order to make them consistent with the velocities from the field in the second column.}}
\end{table}