\begin{table}%t1
\par
\caption{\label{tab:k2}Values of $\kappa_2$ for a $20\%$ bandwidth, for different central frequencies $\nu_0$.\tablefootmark{1}} 
\small%\centering
\par
%\vspace*{2mm}
\begin{tabular}{ccc}
\hline
\hline
\noalign{\smallskip}
  30~GHz& 90~GHz & 250~GHz\\ 
$\sim$$1{-}10^{-3}$& $\sim$$1{-}10^{-2}$ & $\sim$$1+10^{-2}$ \\ 
\hline 
\end{tabular}
\tablefoot{\tablefoottext{1}{We assume that the instrument is observing, through the Gaussian bandpass function defined in Eq.~(\ref{eq:gaussbp}), a 3~K black body source whose intensity is given by Eq.~(\ref{eq:bbintensity}). }  }
\vspace*{3mm}
\end{table}