\begin{table}%t1
%\centering
\par
\caption{\label{tab:datastd}The circular polarization of linearly polarized standard stars.}
\par
\begin{tabular}{lccr}
\hline\hline \noalign{\smallskip}
Object &  $p_{\rm lin}$ (\%) &  $\theta_{\rm lin}$ ($\degr$) & $p_{\rm circ}$ (\%) \\ 
\hline 
Hilt 652   & 6.25  $\pm$ 0.03 & 179.2  $\pm$ 0.2\tablefootmark{a} &     0.003 $\pm$ 0.021 \\
Ve~6$-$23  & 8.26  $\pm$ 0.05 & 171.6  $\pm$ 0.2\tablefootmark{a} &  $-$0.050 $\pm$ 0.035 \\
HD155197   & 4.38  $\pm$ 0.03 & 103.2  $\pm$ 0.2\tablefootmark{b} &     0.033 $\pm$ 0.025 \\  
\hline
\end{tabular}
\tablefoot{All these polarization measurements were obtained
in the $V$~filter. References for linear polarization: 
\tablefoottext{a}{Fossati et~al. (\cite{FOS07});} 
\tablefoottext{b}{Turnshek et~al. (\cite{TUR90}). }}
\end{table}