\begin{table}%T2
\caption{\label{beam2} Observed line ratios$^{a}$.}
%\centerline
 {\small
\begin{tabular}{lcc}
\hline\hline
Species & Transitions & Line ratio\\[4pt]
\hline
CO & 2--1/1--0 & 0.43\\
HCO$^+$ & 3--2/1--0 & 0.42\\
HNC & 3--2/1--0 & 0.75\\
HCN & 3--2/1--0 & 0.22$^{b}$\\
CN & 2--1/1--0 & 0.31--0.56$^{c}$\\
H$_2$CO & 3(1, 2)--2(1, 1)/2(1, 2)--1(1, 1) & 0.31\\
HC$_3$N & 16--15/10--9 & 0.91$^{d}$\\
HC$_3$N & 25--24/10--9 & 0.47\\
\hline 
\end{tabular}}
\smallskip
$^a$ If $\theta_{\rm s}$ is the Gaussian source size (assumed to be 2$\arcsec$ (see Sect.~2.1)),
and $\theta_{\rm b}$ is the beam size for the line,
the ratio of integrated intensities for transition $X$ and $Y$, corrected for beam and
source-size, is assumed to scale according to 
$ R~ = ~{ \int T_{\rm mb}^*(X) {\rm d}V ~ (\theta_{\rm b}^2(X) + \theta_{\rm s}^2)  \over
 \int T_{\rm mb}^*(Y) {\rm d}V ~ (\theta_{\rm b}^2(Y) + \theta_{\rm s}^2) }$. 
Errors in line ratios are $\approx$20\% including rms
and calibration errors. 
$^b$ We used the interferometric line ratio
between HCN and HCO$^+$ 1--0 measured by Imanishi \etal\  (\cite{Imanishi04}) to scale our observed HCO$^+$ 1--0
line into an expected HCN~1--0 intensity (see Sect.~2.1). 
$^c$ Integrated intensity
ratio is 0.56 (too high due to the missing CN~1--0 emission) and the peak-to-peak is
0.31 (see Sect.~2.1). 
$^d$ The line ratio is somewhat uncertain due to para-H$_2$CO
contamination (see Sect.~2.1).
\end{table}