\begin{table}%t1
\caption{\label{tab_labdata}Spectroscopic parameters for the observed \cthree\ transitions.}
%\centering
$$
\begin{tabular}{p{0.5cm}r@{$\leftarrow$}lr@{.}lcrr}
\hline \hline \noalign{\smallskip}
Name & \multicolumn{2}{c}{Transition}   &
\multicolumn{2}{c}{Frequency\tablefootmark{a}} & 
{A-coeff} & $E_l$\\
\ & ($J^\prime$, $v^\prime$)&($J,v$)
& \multicolumn{2}{c}{[MHz]} & $10^{-3}$ s$^{-1}$ &  [K]\\
\hline \noalign{\smallskip}
$P(10)$ & (9, 1) & (10, 0)& 1654081&66(4.68)\tablefootmark{b}  &  2.38 & 47.3\\
$P(4)$  & (3, 1) & (4, 0) &1787890&57(6.90)  &  2.72 & 8.6 \\
$Q(2)$  & (2, 1) & (2, 0) &1890558&06(0.25)  &   7.51  & 2.6 \\
$Q(4)$  & (4, 1) & (4, 0) &1896706&56(0.15)  & 7.58 &   8.6  \\
\hline
\end{tabular}
$$
\tablefoot {\tablefoottext{a}{Experimental rest frequencies, uncertainties are given in parentheses;}
\tablefoottext{b}{calculated frequency and 1$\sigma$~uncertainty taken from CDMS~catalog.}}
\end{table}