\begin{table}%t1
%\centering
\par
\caption{\label{t:parameters}Parameters of the observed lines of the $N=1{-}0$ transition.}
\begin{tabular}{cccccc}
\hline\hline 
\noalign{\smallskip}
$J^{\prime} \leftarrow J^{\prime\prime}$ & $ F^{\prime} \leftarrow F^{\prime\prime}$ & Frequency & $g_{\rm l}$ & $g_{\rm u}$ & A \\
 &   & (MHz) & & & ($10^{-2}~{\rm s}^{-1}$) \\ 
\hline 
0 1  & 1/2 1/2 & 909045.2 & 2 & 2  &  0.524 \\
0 1  & 1/2 3/2 & 909158.8 & 4 & 2  &  1.048 \\
\hline
\end{tabular}
\tablefoot{The frequencies were taken from \citet{bekooy+1985} and the Einstein~$A$ coefficients from the Cologne Database for Molecular Spectroscopy \citep[CDMS,][]{mueller+2005}. Note that the Einstein~$A$ coefficients given by \citet{dealmeida1990}  are too high by a factor~1.5.}\vspace*{1.5mm}
\end{table}