\begin{table}
\caption{\label{tab:col}CH column densities.}
%\centerline
 {\begin{tabular}{lcccc}
\hline
\hline
\noalign{\smallskip}
Name & $V_{\rm min}$ &  $V_{\rm max}$ & $N$(CH) & $N$(H$_2$)\tablefootmark{a}  \\
     & \kms & \kms & 10$^{13}$ cm$^{-2}$ &  10$^{21}$ cm$^{-2}$   \\
\hline
G10.6--0.64 & 10 & 20 & $14 \pm 1 $& 3.9\\
(W31C)                  & 20 & 25 & $9.8 \pm 1 $ & 2.7 \\
                  & 25 & 35 & $26 \pm 1 $ & 7.3\\
                  & 25 & 42 & $17 \pm 1 $ & 4.8 \\
                  & 42 & 47 & $3.3 \pm 1 $ & 0.9\\
W49N & 30 & 50 & $13 \pm 1 $ & 3.7\\
     & 50 & 78  & $24 \pm 1$ & 6.6\\
     & 67 & 71 & $1.5 \pm 0.2 $ &0.4 \\
W51 & 3& 10 &  $3.7 \pm 0.2 $ & 1.0\\
    & 10 & 15 & $0.5 \pm 0.15 $ & 0.14  \\
    & 42 & 47 & $1.8 \pm 0.15 $ & 0.5 \\
\hline
\end{tabular}}
\tablefoot{
\tablefoottext{a}{Based on [\CH]/[H$_2$] = $3.5 \times 10^{-8}$ (Sheffer et~al. 2008).}}
\end{table}