\begin{table}%t4
%%\centering

\par
\caption{\label{tab:param}Inter-chip transformation parameters, with formal errors.}
\begin{tabular}{ccccc}
\hline
\hline\noalign{\smallskip}
Parameter &       $k = [1]$ & $k = [2]$ & $k = [3]$ &  $k = [4]$\\
\hline\noalign{\smallskip}
$\alpha_{k}/\alpha_{[2]}$&1.01482&1.00000&1.01445&1.0073\\
                &$\pm$0.00006& &$\pm$0.00006& $\pm$0.0001\\
$\theta_{k}{-}\theta_{[2]}$&$-$0.175&0.000&0.198&0.005\\
                &$\pm$0.003&&$\pm$0.04&$\pm$0.003\\
$(x_{[2]}^{\rm corr})_k$&3135.0&1025.00&$-$1088.1&948.36\\
                &$\pm$0.1& &$\pm$0.1 &$\pm$0.08\\
$(y_{[2]}^{\rm corr})_k$&2311.2& 2305.00&2307.4& 5684.9\\
                &$\pm$0.1& &$\pm$0.1&$\pm$0.2\\
\hline
\end{tabular}
\tablefoot{The absolute $x$-scale factor of chip [2] in its reference pixel is
  $229.7 \pm 0.1$~mas.  The values for $\theta$ are expressed in
  degrees.}\vspace*{-2mm}
\end{table}