\begin{table}%t4
\caption{\label{table:2}\textit{Planck} reflector characteristics at ambient temperature and 40~K.} 
%\centering
\par
\begin{tabular}{c c c c c}         
\hline\hline \noalign{\smallskip}                
Reflector & Design parameter & Ambient temperature\tablefootmark{a} & Estimated in-flight parameter & Estimated uncertainty \\   
\hline                        
   {PR} & $R=1440.0~{\rm mm}$ & $R=1440.41~{\rm mm}$& $R=1439.266~{\rm mm}$& ${\pm}0.1~{\rm mm}$ \\      & $k=-0.869417$ & $k=-0.86782$ & $k=-0.867266$    & $\pm 0.001$ \\
    & $\rm rms~(ring~1, \mu m)= $ 7.5 & 3.5 &  5.0\tablefootmark{b}& \\
    & rms (ring 2, $\rm \mu m)= $ 12 & 4.2 & 8.2 & \\
    & rms (ring 3, $\rm \mu m)= $ 20 & 5.3 & 8.8 & \\
    & rms (ring 4, $\rm \mu m)= $ 33 & 6.0 & 8.6 & \\
    & rms (ring 5, $\rm \mu m)= $ 50 & 16.0 & 12.6 & \\
    & rms (whole surface, $\rm \mu m)= $ & 7.0 & 8.6 & \\
    \hline
   {SR} & $R=643.972~{\rm mm}$ & $R=644.043~{\rm mm}$ & $R=643.898~{\rm mm}$& $\pm 0.1~{\rm mm}$ \\
    & $k=-0.215424$ & $k=-0.21541$  & $k=-0.215094$    & $\pm 0.001$ \\
    & rms (ring 1, $\rm \mu m)= $ 7.5 & 3.6 &  4.7\tablefootmark{c} & \\
    & rms (ring 2, $\rm \mu m)= $ 12 & 3.9 & 4.5 & \\
    & rms (ring 3, $\rm \mu m)= $ 20 & 6.2 & 7.0 & \\
    & rms (ring 4, $\rm \mu m)= $ 33 & 5.3 & 5.7 & \\
    & rms (ring 5, $\rm \mu m)= $ 50 & 11.5 & 13.2 & \\
    & rms (whole surface, $\rm \mu m)= $ & 6.1 & 10.6 & \\
    & Core-wall print-through $\rm (\pm \mu m)= $\tablefootmark{d} &  & 0.4 & \\
    & PTV (dimpling, $\rm \mu m)= $\tablefootmark{e} &  & $<$0.7 & \\
 \hline                                   
\end{tabular}
\tablefoot {\tablefoottext{a}{All rms at room temperature derived from the surface shape measured with a contact probe and a resolution of 2~cm. The ring definition is as in Table~\ref{tabrefreq}.} \\
\tablefoottext{b}{Derived from the photogrammetric image of Fig.~\ref{FigReflectorDef}. The rms values quoted are actually standard deviations of the distribution of values in each ring, i.e.~they are with respect to the mean difference to the best-fit-ellipsoid within each ring. A~real rms with respect to the best-fit-ellipsoid would increase the rms in the innermost ring by a factor of $\sim$4~-- largely due to the prominent bump visible in the middle of the primary in Fig.~\ref{FigReflectorDef}, and of the next two rings by a smaller factor.} \\
\tablefoottext{c}{Derived from the interferometric image of Fig.~\ref{FigSRInterMap}. The rms values quoted are actually standard deviations of the distribution of values in each ring, i.e.~they are with respect to the mean difference to the best-fit-ellipsoid within each ring. A~real rms with respect to the best-fit-ellipsoid would increase the rms in the inner two rings by a factor of~$\sim$2~-- largely due to the circular shelf-like feature visible in Fig.~\ref{FigReflectorDef} and associated to the three ISMs. It~is also interesting to note that the combination of interferometric data to the photogrammetric data has increased the rms by about 15\% as compared to the photogrammetric surface only.} \\
\tablefoottext{d}{Not measured for the PR.} \\
\tablefoottext{e}{Not measured for the PR.}}
\end{table}