\begin{table}%t1 \caption{\label{tab:pdbi-info}Observation parameters of the PdBI maps shown in Fig.~\ref{fig:pdbi-maps}.} %\centerline {\tiny \begin{tabular}{ccrclccccccr} \hline \hline\noalign{\smallskip} Molecule & Transition & Frequency & Instrument & Config. & Beam & PA & Vel. Resol. & Int. Time$^{a}$ & $T_\emr{sys}$ & Noise$^{b,\dagger}$ & \multicolumn{1}{c}{Obs. date} \\ && GHz &&& arcsec & $\deg$ & \kms{}& hours& K & K & \\ \hline\noalign{\smallskip} \HthCOp{} & 1--0 & 86.754288 & PdBI & C \& D & $ 6.8 \times 4.7$ & 13 & 0.2 & 6.5 & 150 & 0.10 & 2006-07 \\ HCO & $1_{0,1}~3/2, 2$--$0_{0,0}~1/2,1$ & 86.670760 & PdBI & C \& D & $ 6.7 \times 4.4$ & 16 & 0.2 & 6.5 & 150 & 0.09 & 2006-07 \\ \hline \end{tabular}} \medskip $^{a}$ We observed a 7-field mosaic centered on the IR peak at $\alpha_{2000} = 05^{\rm h}40^{\rm m}54.27^{\rm s}$, $\delta_{2000} = -02\deg 28'00''$ (\cite{abe03}) with the following offsets: ($-$5.5$''$, $-$22.0$''$), (5.5$''$, $-$22.0$''$), (11.0$''$, 0.0$''$), (0.0$''$, 0.0$''$), ($-$11.0$''$, 0.0$''$), ($-$5.5$''$, 22.0$''$) and (5.5$''$, 22.0$''$). The total field-of-view is $80.1''\times 102.1''$ and the half power primary beam is 58.1$''$. The mosaic was Nyquist sampled in declination at 3.4~mm and largely oversampled in right ascension. This maximizes the field of view along the PDR edge while the oversampling in the perpendicular direction eases the deconvolution. On-source time was computed as if the source was always observed with 6 antennae; $^{b}$~the noise values refer to the mosaic phase center (mosaic noise is inhomogeneous due to primary beam correction; it steeply increases at the mosaic edges). \end{table}