\begin{table}%T3
\par
\caption{\label{tab:polar}Raw squared visibility in natural light (Col.~4) and in polarized light (Cols.~5 and~6) computed on a 6.6~nm-wide spectral channel centered on $\lambda$ (Col.~3).}
\small
%\centerline
{
\begin{tabular}{rcrrccc}
\hline\hline\noalign{\smallskip}
$\delta$ & HA(h)& $\lambda$(nm) & $V^{2}_{\rm Nat}$ & $V^{2}_{\rm High}$ & $V^{2}_{\rm Low}$\\
\noalign{\smallskip}\hline\noalign{\smallskip}
29$^\circ$ & [0;+5] & 640 & 0.36 $\pm$ 0.02 & 0.34 $\pm$ 0.02 & 0.36 $\pm$ 0.03\\
29$^\circ$ & [0;+5]& 650 & 0.34 $\pm$ 0.03 & 0.36 $\pm$ 0.02 & 0.38 $\pm$ 0.04\\
\hline\noalign{\smallskip}
52$^\circ$ & [--1;+4]& 640 & 0.40 $\pm$ 0.04 & 0.34 $\pm$ 0.03 & 0.38 $\pm$ 0.02\\
52$^\circ$ & [--1;+4]& 650 & 0.38 $\pm$ 0.03 & 0.38 $\pm$ 0.03 & 0.44 $\pm$ 0.01\\
\hline\noalign{\smallskip}
63$^\circ$ & [--1;+4]& 640 & 0.26 $\pm$ 0.01 & 0.24 $\pm$ 0.01 & 0.24 $\pm$ 0.02\\
63$^\circ$ & [--1;+4] & 650 & 0.28 $\pm$ 0.01 & 0.28 $\pm$ 0.02 & 0.28 $\pm$ 0.02\\
\hline
\end{tabular}}
\smallskip
 Each value corresponds to a mean of the hour angle range of observations (Col.~2). Three calibrators of different declinations (Col.~1) have been observed. $r_0$ for these observations was stable with a mean value of about~8~cm. 
\end{table}