\begin{table}%t1
\small\caption{Parameters of observed rotational transitions.}\label{tab:freq_list}
%\centerline
{\begin{tabular}{lrcc}
\hline\hline\noalign{\smallskip}
 Species & Transition       & $E_{\rm l}^a$ (K) & $\nu$~(MHz)  \\
\noalign{\smallskip}\hline
\AMM\          & $(J,K=1,1)$              &    22.70        & 23~694.496    \\
\AMM\          & $(J,K=2,2)$              &    63.89        & 23~722.633    \\
 \DAMM\ (para) & 1$_{11}$--1$_{01}$       &    16.55        & 85~926.3      \\
 \DAMM\ (ortho)& 1$_{11}$--1$_{01}$       &    15.98        & 110~153.6     \\
\DDAMM\ (ortho)& 1$_{10}$--1$_{01}$       &    13.33        & 110~812.9      \\
\DDAMM\ (para) & 1$_{10}$--1$_{01}$       &    13.09        & 110~896.7     \\
 \CO\          & $J=1$--0                 &    0.0          & 109~782.1734  \\
 \CO\          & $J=2$--1                 &    5.27         & 219~560.3568  \\
 \COs\         & $J=2$--1                 &    5.39         & 224~714.3850  \\
 \htcn\        & $J=1$--0, $F=2$--1       &    0.0          & 86~340.184    \\
 \hcfn\        & $J=1$--0                 &    0.0          & 86~054.961    \\
\hline
\end{tabular}}
\smallskip
Note: $^a$~$E_{\rm l}$ is the lower energy level of the transition.
\end{table}