\begin{table}%t4
\par
    \caption{\label{tab:abund}Inferred column densities and abundances with respect to
      molecular hydrogen, \eg{} $\chi(\mbox{X})=N(\mbox{X})/N(\HH)$.}
 %   %\begin{center}
\par
      \begin{tabular}{lccc} 
        \hline \hline
        Molecule      & Method & HCO peak    &  DCO$^+$ peak \\
\hline
$N$(H$_2$)~[\pscm]   & 1.2~mm cont.        & $1.9 \times 10^{22}$  &  $2.9 \times 10^{22}$\\\hline
$N$(\HCO)~[\pscm]    &  \Tex{} = 5 K      & $3.2 \times 10^{13}$  &  $4.6 \times 10^{12}$\\
$N$(\HthCOp)~[\pscm] &  Full excitation     & $5.8 \times 10^{11}$  &  $5.0 \times 10^{12}$ $^*$\\
$N$(\HCOp)~[\pscm]   & $^{12}$C/$^{13}$C = 60 & $3.5 \times 10^{13}$  &  $3.0 \times 10^{14}$\\\hline
$\chi$(\HCO)          &                      & $1.7 \times 10^{-9}$  &  $1.6 \times 10^{-10}$~$^{\dagger}$\\
$\chi$(\HthCOp)       &                      & $3.1 \times 10^{-11}$ &  $1.7 \times 10^{-10}$\\
$\chi$(\HCOp)         &                      & $1.8 \times 10^{-9}$  &  $1.0 \times 10^{-8}$\\
\hline
\end{tabular}
\par
\medskip
$^*$ Pety et~al. (2007a).\\
$^{\dagger}$~$1.7 \times 10^{-9}$ if HCO arises only from the cloud surface ($A_{\rm V}\simeq3$).
%%\end{center}
\par
\end{table}