\begin{table}%t5
\caption{\label{8ghz}Maxima and minima in flux density, position angle and core separation at epochs~1987, 1988.5, 1990, and 1991 at~8.4~GHz.}
%\centering
\par
\begin{tabular}{lcccccccccccc}
\hline \hline\noalign{\smallskip}
\multicolumn{1}{c}{Time} & \multicolumn{3}{c}{{1987}} & \multicolumn{3}{c}{{1988.5}} & \multicolumn{3}{c}{{1990}} & \multicolumn{3}{c}{{1991}}\\
Comp. ID & Flux & PA & Core sep. & Flux & PA & Core sep. & Flux & PA & Core sep.& Flux & PA & Core sep.\\
\hline
Core & max & & & min& & & max & & & min& & \\
C0 & & & max& & & min& & & max& min & & min\\
C1 & min & min & min & max & max & max & min & min & min & max & max &max  \\
Ca & max  & max & min & min  & min & max & max & max & min & & & \\
\hline
\end{tabular}
\end{table}