\begin{table}%t3
\caption{\label{tab3}Raw measurements of all Stokes parameters for unpolarized sources.}
%\centerline
 {\small \begin{tabular}{lrrrrrrrrrrrr}
\hline\hline
Source & $I_{\rm m}$ & $\sigma_{\Delta}$ & $Q_{\rm m}$ & $\sigma_{\Delta}$ & $U_{\rm m}$ & $\sigma_{\Delta}$ & $V_{\rm m}$ & $\sigma_{\Delta}$ & $LP$ & $\sigma_{\Delta}$ & $CP$ & $\sigma_{\Delta}$\\
\hline
& [K] & & [K] & & [K] & & [K] & & [\%] & & [\%] &\\
NGC~6572$^c$ & 3.861 & 0.008 & --0.016 & 0.002 & 0.006 & 0.013 & --0.016 & 0.004 & 0.43 & 0.12 & --0.42 & 0.11 \\
NGC~7027 & 17.100 & 0.300 & --0.076 & 0.011 & --0.014 & 0.015 & --0.087 & 0.022 & 0.45 & 0.07 & --0.51 & 0.13 \\
\hline
\end{tabular}}
\medskip
$^c$ Measurements were carried out at Effelsberg at 6~cm and calibrated using a noise diode of known strength, but a D-term correction was not applied.
\end{table}