\begin{table}
%\centering
\par
\caption{\label{TabFit13CHp}$^{13}$CH$^{+}$ $(0{-}1)$ absorption line analysis results.}
\begin{tabular}{l  l  c  c  c  c  c  c}
\hline\hline
\noalign{\smallskip}
Source     & Remark\tablefootmark{a} & $\upsilon_0$ & $\Delta \upsilon$ & $\tau_0$ & $N$($^{13}$CH$^{+}$)  & $N$(CH$^{+}$)\tablefootmark{b}         \\
           &        & (km s$^{-1}$)& (km s$^{-1}$)     &          & ($10^{12}$ cm$^{-2}$) & ($10^{14}$ cm$^{-2}$) \\
\hline
{\bf \object{W49N}} &   E    & 11.89 $\pm$  0.05 &  7.46 $\pm$  0.12 &  0.28 $\pm$  0.01 & 
$>$6.7 & $>$3.35 \\
           &        & 38.15 $\pm$  0.31 & 17.50 $\pm$  0.83 &  0.07 $\pm$  0.01 &  3.77 $\pm$  0.30 &  1.89 $\pm$  0.15  \\
           &        & 61.29 $\pm$  0.20 & 13.49 $\pm$  0.48 &  0.09 $\pm$  0.01 &  4.07 $\pm$  0.25 &  2.04 $\pm$  0.13  \\[0.4cm]
{\bf \object{W51}}  &   E       & 48.65 $\pm$  0.11 & 1.05 $\pm$ 0.25 & 0.06 $\pm$ 0.01 &  $>$0.2  &  $>$0.1  \\
           &   E       & 53.84 $\pm$  0.10 & 4.73 $\pm$ 0.25 & 0.13 $\pm$ 0.01 &  $>$2.0  &  $>$1.0   \\
           &   E       & 64.10 $\pm$  0.15 & 3.18 $\pm$ 0.63 & 0.10 $\pm$ 0.03 &  $>$1.0  &  $>$0.5   \\
           &   E       & 67.56 $\pm$  0.78 & 7.09 $\pm$ 1.02 & 0.09 $\pm$ 0.01 &  $>$2.2  &  $>$1.1   \\
\hline
\end{tabular}
\tablefoot {
\tablefoottext{a}{E = absorption line profile observed in the star-forming
  region. $T_{\rm ex}$ may be underestimated, hence the lower limit on $N(\thCHp)$. }
\tablefoottext{b}{Derived from $N(\thCHp)$ assuming a \twCHp/\thCHp\ isotopic ratio of 50.}}
\end{table}