\begin{table}%t4
\caption{Temperature and column density estimates. $\theta_{\rm s}$ and 
$D$ are the angular and linear source diameter, respectively. \Tk\ is the
kinetic temperature, and $N_{\rm tot}$ the total column density of the
corresponding molecular species.}
\label{tk}
%\centering
\par
\begin{tabular}{ccccc}
\hline  \hline
Tracer  &  $\theta_{\rm s}$ & $D$ & \Tk\  & $N_{\rm tot}$  \\
    & (\asec\ ) & (pc) & (K) &  (\cmq\ )  \\
\hline
\ace\ (PdBI) & 1.4  & 0.033 & 42 $\pm$ 1 & $(1.8\pm0.2) \times 10^{14}$ \\
\AMM\  (VLA) &  $\sim$$5$ & 0.12 &  26 $\pm$ 6  & $\sim$$6 \pm 2 \times 10^{15}$ \\ 
\ace\ (30 m)$^{*}$  &  18 & 0.43 &  34 $\pm$ 6 & $(5\pm0.2) \times 10^{15}$ \\ 
\CIII\ (30 m)$^{*}$ &  15  & 0.35 & 15 $\pm$ 5 & $\sim$$4 \pm 2 \times 10^{15}$ \\
\hline  
\noalign{\smallskip}
\multicolumn{5}{l}{\hspace*{-0.5cm}$^{*}$ Corrected for source size.}
\end{tabular}
\end{table}