\begin{table}%t4
%\centering
\small
\caption{Cross-polarization and principal axis angle measurements
for all the channels. The polarization angle and the beam filling
values refer to measurements on the complete instrument obtained
with the apparatus described in Fig. \ref{fig:paolorizer}, while
the on-axis measurements refer to measurements on the receiver
alone, obtained with the apparatus described in Fig.~\ref{fig:rotator} and also in a test cryostat testing single
channels.  \label{tab:crosspol}}
\begin{tabular}{lrrcc}
\hline \hline
\noalign{\smallskip}
Channel & \multicolumn{2}{c}{Polarization angle (deg)} & \multicolumn{2}{c}{Cross-polarization $\epsilon$}\\
     & nominal & measured & on-axis & beam-filling\\
\hline 
145W1 & 135.0  & $137.1 \pm 2.0$ & $0.080 \pm 0.006$ & $0.11 \pm 0.02$ \\
145W2 & 45.0   & $44.4  \pm 2.0$ & $0.062 \pm 0.005$ & $0.11 \pm 0.02$ \\
145X1 & 180.0  & $178.4 \pm 2.0$ & $0.055 \pm 0.013$ & $0.09 \pm 0.02$ \\
145X2 & 90.0   & $88.7  \pm 2.0$ & $0.070 \pm 0.008$ & $0.13 \pm 0.02$ \\
145Y1 & 157.5  & $158.6 \pm 2.0$ & $0.051 \pm 0.012$ & $0.11 \pm 0.02$ \\
145Y2 & 67.5   & $66.2  \pm 2.0$ & $0.060 \pm 0.006$ & $0.11 \pm 0.02$ \\
145Z1 & 112.5  & $109.8 \pm 2.0$ & $0.182 \pm 0.004$ & $0.22 \pm 0.02$ \\
145Z2 & 22.5   & $21.2  \pm 2.0$ & $0.088 \pm 0.008$ & $0.12 \pm 0.02$ \\
\hline
245W  & 135.0  & $139.2 \pm 2.0$ & $0.007 \pm 0.005$ & $0.02 \pm 0.02$ \\
245X  & 45.0   & $42.9  \pm 2.0$ & $0.007 \pm 0.005$ & $0.02 \pm 0.02$ \\
245Y  & 180.0  & $178.7 \pm 2.0$ & $0.000 \pm 0.015$ & $0.03 \pm 0.02$ \\
245Z  & 90.0  &  $85.2  \pm 2.0$ & $0.014 \pm 0.013$ & $0.01 \pm 0.02$ \\
\hline
345W  & 135.0  & $139.9 \pm 2.0$ & $0.008 \pm 0.005$ & $0.01 \pm 0.02$ \\
345X  & 45.0   & $42.6  \pm 2.0$ & $0.008 \pm 0.001$ & $0.01 \pm 0.02$ \\
345Y  & 180.0  & $178.7 \pm 2.0$ & $0.004 \pm 0.014$ & $0.02 \pm 0.02$ \\
345Z  & 90.0   & $84.9  \pm 2.0$ & $0.019 \pm 0.013$ & $0.02 \pm 0.02$ \\
\hline
\end{tabular}
\end{table}