\begin{table}%t1
\caption{\label{t1}Critial density for molecular transitions.}
%\centering
\par
\begin{tabular}{lll}
\hline \hline
\noalign{\smallskip}
Molecule & Transition designation & Critical density  \\
                  &               &  (cm$^{-3}$)         \\
\hline \\[-3.2mm]
CO    & $J = 1{-}0$                 & $2.0\times 10^3$  \\	  
CO    & $J = 2{-}1$                 & $1.4\times 10^4$  \\	  
\HCOP & $J = 1{-}0$                 & $2.2\times 10^5$  \\	  
CN    & $N = 1{-}0$, $J = 3/2{-}1/2$  & $4.0\times 10^5$  \\	      
CS    & $J = 3{-}2$	             & $1.4\times 10^6$  \\
HCN   & $J = 1{-}0$	             & $3.1\times 10^6$  \\
HNC   & $J = 1{-}0$	             & $3.9\times 10^6$  \\
CN    & $N = 2{-}1$, $J = 5/2{-}3/2$  & $1.9\times 10^7$  \\
\hline 
\end{tabular}
\tablefoot{Based on data from LAMDA database for a kinetic temperature of 60--70 K \citep{SchoierEA2005}.}
\end{table}