\begin{table}%t3
%\centering
\par
%\begin{minipage}[t]{\linewidth}
%\renewcommand{\footnoterule}{}
\caption{\label{tab3} Polarization in percent as a function of aperture diameter\tablefootmark{c}.}
\begin{tabular}{c c c c c c}     
\hline\hline                  
Date&$D$&3000&6000&12~000&24~000\\
2008--2009&Filters&(km)&(km)&(km)&(km)\\
\hline                    
December&&&&\\
25.60&CR&4.0 $\pm$ 0.7&4.5 $\pm$ 0.4&4.5 $\pm$ 0.5&$S/N$\\
26.62&CR&4.1 $\pm$ 0.8&4.8 $\pm$ 0.5&4.8 $\pm$ 0.8&$S/N$\\
27.59&CR&4.2 $\pm$ 0.3&4.4 $\pm$ 0.3&4.4 $\pm$ 0.3&$S/N$\\
27.59&CB&4.4 $\pm$ 0.5&4.5 $\pm$ 0.5&4.5 $\pm$ 0.5&$S/N$\\
27.63&$R_{\rm b}$&4.5 $\pm$ 0.3&4.4 $\pm$ 0.5&3.9 $\pm$ 0.5&3.8 $\pm$ 0.8\\
March&&&&&\\
17.81&$R$&5.2 $\pm$ 1.0&5.1 $\pm$ 0.3&5.6 $\pm$ 0.4&5.8 $\pm$ 0.5\\
18.78&$R$&6.3 $\pm$ 0.9&4.9 $\pm$ 0.3&5.2 $\pm$ 0.3&5.2 $\pm$ 0.3\\
19.80&$R$&5.9 $\pm$ 1.1&5.8 $\pm$ 0.5&5.6 $\pm$ 0.3&5.4 $\pm$ 0.3\\
April--May&&&&&\\
30.60&$R_{\rm b}$&2.7 $\pm$ 0.8&2.5 $\pm$ 0.8&2.5 $\pm$ 1.1&$S/N$\\
01.70&$R_{\rm b}$&2.5 $\pm$ 0.5&2.3 $\pm$ 0.5&2.3 $\pm$ 0.8&Star trails\\
\hline                  
\end{tabular}
\tablefoot{\tablefoottext{c}{$D$ = projected diameter. Filters: see Table~\ref{tab1} caption. $S/N$: signal over noise ratio $\leq$$3$. Star trails in the cometary coma. In the error bars, systematic errors (subtraction of the background, error bars on the standard stars) are included.}}
%\end{minipage}
\end{table}