\begin{table}%t2
\caption{\label{tab2}Deviation from the best fit parabolic surface.}
%\centerline
 {\small \begin{tabular}{lcc}
\hline\hline
Elevation & Deviation &  Deviation \\
\hline
$[^{\circ}]$ & [rms mm] & [\% @ 6~cm]\\
30 to 60$^b$ & 0.5 & 0.8 \\
20 to 75 & 0.8 & 1.3 \\
\hline
\end{tabular}}
\smallskip
$^b$ Typical values measured at Effelsberg. 
\end{table}