\begin{table}%t1 \caption{\label{obs_lines}Observed lines.} %\centerline { \small\begin{tabular}{llrr} \hline\hline Telescope & Transition & Rest Freq. & $E_{\rm upper}$ \\ & & [GHz] & [K] \\ \hline PdBI & H$^{13}$CO$^{+}$ 1 $\rightarrow$ 0 & 86.754 & 4 \\%86.754330 PdBI & SiO 2 $\rightarrow$ 1 & 86.847 & 6 \\%86.847010 PdBI & HN$^{13}$C 1 $\rightarrow$ 0 & 87.091 & 4 \\%87.090859 SMA & C$^{18}$O 2 $\rightarrow$ 1 & 219.560 & 16 \\%219.560353 SMA & $^{13}$CO 2 $\rightarrow$ 1 & 220.399 & 16 \\%220.398681 SMA & CH$_3$OH 8$_{-1}$ $\rightarrow$ 7$_0$ E & 229.759 & 89 \\%229.758811 SMA, 30~m & CO 2 $\rightarrow$ 1 & 230.538 & 17 \\%230.538000 SMA & N$_2$H$^+$ 3 $\rightarrow$ 2 & 279.512 & 27 \\%279.511732 SMA & CH$_3$OH 6$_0$ $\rightarrow$ 5$_0$ E & 289.939 & 62 \\%289.939386 SMA & CH$_3$OH 6$_{-1}$ $\rightarrow$ 5$_{-1}$ E & 290.070 & 54 \\%290.069824 SMA & CH$_3$OH 6$_{0}$ $\rightarrow$ 5$_{0}$ A & 290.111 & 48 \\%290.110666 SMA & CH$_3$OH 6$_{1}$ $\rightarrow$ 5$_{1}$ E & 290.249 & 70 \\%290.248762 SMA & CH$_3$OH 6$_{-2}$ $\rightarrow$ 5$_{-2}$ E & 290.307 & 75 \\%290.307294 %SO 6_5$\rightarrow$ 5_4 & 219.949433 & \\ \hline \end{tabular}} \end{table}