\begin{table}%t2
\caption{\label{tab_gaussfit}Parameters derived from simultaneous Gaussian fitting to all
the line profiles and column densities estimated from the fitted \mbox{intensities}.}
\par
%\centering
\par
\begin{tabular}{lllllll}
\hline \hline  \noalign{\smallskip}
\multicolumn{1}{c}{Transition} &
\multicolumn{3}{c}{W31C} &
\multicolumn{3}{c}{W49N} \\
&\hspace*{0.3cm}\Tc & $\int{\tau {\rm d}v}$ & \hspace*{0.2cm}$N_{\rm l}$
&\hspace*{0.3cm}\Tc & $\int{\tau {\rm d}v}$ & \hspace*{0.2cm}$N_{\rm l}$\\
& \hspace*{0.3cm}[K] &  
[km/s]  
&  [\cmsq] &\hspace*{0.3cm}[K] &   [km~s$^{-1}$]   & [\cmsq]\\
\hline \noalign{\smallskip}
$P(10)$& 11.4 $\pm$ 0.4 & 0.51 & 1.0 $\times$ 10$^{14}$ & \ldots       &  \ldots \ldots\\
$P(4)$ & 10.5 $\pm$ 0.3 & 0.61 & 1.5 $\times$ 10$^{14}$ & 16.8 $\pm$ 0.2 & 0.62 & 1.6 $\times$ 10$^{14}$  \\
$Q(2)$ & 11.8 $\pm$ 0.2 & 0.87 & 7.2 $\times$ 10$^{13}$ & 18.3 $\pm$ 0.3 &  0.87  & 7.3 $\times$ 10$^{13}$\\
$Q(4)$ & 11.8 $\pm$ 0.2 & 1.22 & 1.0 $\times$ 10$^{14}$ & 18.3 $\pm$ 0.2 & 0.90 &  7.6 $\times$ 10$^{13}$\\
\hline
\end{tabular}
\tablefoot {The fitted values of line center and linewidth are: for W31C $V_{\rm cen}$~= $-$0.09~$\pm$ 0.06~\kms\ and $\Delta V$~= 4.5~$\pm$ 0.1~\kms\ and  for W49N $V_{\rm cen}$~= 11.0~$\pm$ 0.1~\kms, and $\Delta V$~= 5.3~$\pm$~0.2~\kms.}
\vspace*{-4mm}
\end{table}