\begin{table}%t2
\caption{\label{tab:table2}Comparison between the models for the local astrometric solution$^{{a}}$.}
\small%\centerline
 {
\begin{tabular}{lcccc}
        \hline \hline
%&&&& \\[-8pt]
        Solution &  
        $\overline{\Delta\alpha \cos \delta}$ &
        $\sigma_{\Delta\alpha \cos \delta}$ & 
        $\overline{\Delta\delta}$ &
        $\sigma_{\Delta\delta}$ \\ 
        \hline 
        3${\rm rd}$ degree  & $+$42 & 126 & $-$25 & 140 \\
        2${\rm nd}$ degree  & $+$43 & 127 & $-$23 & 136 \\
        1${\rm st}$ degree  & $+$61 & 110 & $-$34 & 120 \\
        0 degree         & $+$42 & 126 & $-$34 & 119 \\
        offset           & $+$56 & 118 & $-$45 & 130 \\
        \hline 
 %&&&& \\[-8pt]       
        Solution &  
	        $\overline{\Sigma _X}$ &
	        $\sigma_{\Sigma X}$ &
	        $\overline{\Sigma _Y}$ &
                $\sigma_{\Sigma Y}$ \\ 
        \hline 
        3${\rm rd}$ degree  & 137 & 63 & 127 & 64 \\
        2${\rm nd}$ degree  & 134 & 66 & 125 & 64 \\
        1${\rm st}$ degree  & 135 & 68 & 120 & 65 \\
        0 degree         & 133 & 68 & 117 & 64 \\
         \hline  
        \end{tabular}}
  \medskip
$^{a}$ In the top half of the table, the average corrections and their standard deviations are presented. In the bottom half, the average internal error in the solutions and their dispersions are presented. All values are in milli-arcsecs. The difference between the ``0~degree'' and the ``offset'' solutions is just that in the former residuals larger than 2.5$\sigma$ are removed
and the solution is recalculated.
\end{table}