\begin{table}%t1
\caption{\label{tab-masses}Observed and derived parameters for the 24~sources located in the region shown in Fig.~\ref{fig-exmap} and observed in NH$_3$~lines.}
\small%\centerline
 {
\begin{tabular}{llllllllllllll}
\hline
\hline
Source & RA (J2000) & Dec (J2000) & Size & $v_{\rm LSR}$ & $R_G$ & $D_{\rm near}$ & $D_{\rm far}$ & $F_{\rm peak}$ & $F_{\rm int}$ & $T_{\rm kin}$ & $N({\rm H_2})$ & $M_{\rm near}$ & $M_{\rm far}$ \\
& & & $''$ & km~s$^{-1}$ & kpc & kpc & kpc & Jy/b. &
Jy & K & $^{(1)}$ & $M_{\odot}$ & $M_{\odot}$ \\
\hline
 G18.55+0.04 & 18 24 37.85 & --12 45 14.8 & 36 $\times$ 24 &
36.3 & 5.6 & 3.1 & 13.0 & 0.92 &  2.8 & 21.0 &  2.1 &  140 &  2380 \\
G18.61--0.07 & 18 25 08.42 & --12 45 21.6 & 38 $\times$ 26 &
45.8 & 5.2 & {\bf 3.7} & 12.5 & 1.70 &  5.7 & 32.7$^{(2)}$ &  2.2 & {\bf  210} &  2490 \\
G18.63--0.07 & 18 25 09.84 & --12 44 07.5 & 53 $\times$ 21 &
45.7 & 5.2 & {\bf 3.6} & 12.5 & 0.96 &  3.6 & 14.7 &  3.9 & {\bf  420} &  5010 \\
G18.65--0.06 & 18 25 10.63 & --12 42 24.1 & 43 $\times$ 25 &
44.6 & 5.2 & {\bf 3.7} & 12.5 & 2.25 &  8.1 & 18.3 &  6.4 & {\bf  680} &  7940 \\
 G18.66+0.04 & 18 24 50.98 & --12 39 20.8 & 36 $\times$ 24 &
80.9 & 4.0 & 5.2 & 10.9 & 2.10 &  6.3 & 22.4 &  4.5 &  780 &  3510 \\
 G18.70+0.00 & 18 25 02.38 & --12 38 12.6 & 46 $\times$ 34 &
80.3 & 4.0 & 5.1 & 11.0 & 0.84 &  4.5 & 14.8 &  3.4 & 1030 &  4770 \\
 G18.76+0.26 & 18 24 13.27 & --12 27 44.6 & 59 $\times$ 42 &
20.8 & 6.6 & 2.0 & {\bf 14.1} & 1.14 &  9.7 & 15.8 &  4.1 &  320 & {\bf 15090} \\
G18.79--0.29 & 18 26 15.53 & --12 41 36.2 & 40 $\times$ 34 &
65.5 & 4.4 & {\bf 4.5} & 11.6 & 0.94 &  4.3 & 14.4 &  4.0 & {\bf  830} &  5360 \\
G18.83--0.30 & 18 26 23.70 & --12 39 38.9 & 37 $\times$ 28 &
63.5 & 4.6 & {\bf 4.4} & 11.7 & 1.35 &  4.8 & --$^{(3)}$ &  5.3 & {\bf  800} &  5610 \\
G18.83--0.47 & 18 26 59.34 & --12 44 46.5 & 34 $\times$ 32 &
63.3 & 4.5 & {\bf 4.5} & 11.6 & 1.50 &  5.7 & 18.9 &  4.1 & {\bf  680} &  4600 \\
G18.83--0.49 & 18 27 03.57 & --12 45 06.5 & 58 $\times$ 25 &
65.2 & 4.5 & {\bf 4.5} & 11.6 & 1.34 &  6.7 & 20.8 &  3.2 & {\bf  720} &  4640 \\
G18.86--0.48 & 18 27 06.20 & --12 43 09.3 & 38 $\times$ 23 &
65.4 & 4.4 & {\bf 4.6} & 11.5 & 0.73 &  2.1 & 18.8 &  2.0 & {\bf  270} &  1710 \\
G18.88--0.49 & 18 27 09.21 & --12 42 35.1 & 38 $\times$ 25 &
65.5 & 4.5 & {\bf 4.5} & 11.6 & 1.11 &  3.5 & 22.4 &  2.4 & {\bf  340} &  2210 \\
G18.88--0.51 & 18 27 15.13 & --12 42 54.6 & 52 $\times$ 29 &
66.2 & 4.4 & {\bf 4.6} & 11.5 & 0.62 &  3.2 & 23.6 &  1.2 & {\bf  290} &  1840 \\
G18.89--0.47 & 18 27 07.82 & --12 41 38.0 & 64 $\times$ 34 &
66.1 & 4.4 & {\bf 4.6} & 11.5 & 3.39 & 25.4 & 25.9 &  5.9 & {\bf 2040} & 12840 \\
G18.89--0.64 & 18 27 43.46 & --12 45 48.5 & 28 $\times$ 22 &
64.1 & 4.5 & {\bf 4.5} & 11.6 & 0.58 &  1.2 & 20.0 &  1.5 & {\bf  130} &   880 \\
G18.91--0.63 & 18 27 43.55 & --12 44 51.0 & 50 $\times$ 43 &
64.5 & 4.5 & {\bf 4.5} & 11.6 & 1.51 & 11.1 & 17.1 &  4.8 & {\bf 1560} & 10340 \\
G18.93--0.01 & 18 25 32.35 & --12 26 41.4 & 27 $\times$ 25 &
46.3 & 5.1 & 3.7 & 12.4 & 1.33 &  3.1 & 29.3 &  2.0 &  140 &  1530 \\
G18.98--0.07 & 18 25 51.06 & --12 25 42.5 & 26 $\times$ 18 &
61.8 & 4.6 & {\bf 4.4} & 11.7 & 0.82 &  1.3 & 20.4 &  2.0 & {\bf  140} &   960 \\
G18.98--0.09 & 18 25 55.22 & --12 25 50.3 & 30 $\times$ 19 &
63.0 & 4.5 & {\bf 4.4} & 11.6 & 0.64 &  1.3 & 20.7 &  1.5 & {\bf  130} &   900 \\
G18.99--0.04 & 18 25 45.44 & --12 23 54.0 & 38 $\times$ 32 &
59.8 & 4.7 & {\bf 4.3} & 11.8 & 0.31 &  1.3 & 20.7 &  0.7 & {\bf  120} &   930 \\
G19.01--0.03 & 18 25 44.61 & --12 22 42.0 & 40 $\times$ 34 &
59.8 & 4.7 & {\bf 4.3} & 11.8 & 2.18 & 10.1 & 19.5 &  5.7 & {\bf 1070} &  8000 \\
G19.08--0.29 & 18 26 48.77 & --12 26 20.7 & 39 $\times$ 37 &
66.0 & 4.6 & {\bf 4.3} & 11.7 & 4.28 & 21.4 & 24.2 &  8.2 & {\bf 1700} & 12330 \\
 G19.47+0.17 & 18 25 54.50 & --11 52 34.4 & 33 $\times$ 24 &
20.0 & 6.6 & 2.0 & {\bf 14.0} & 6.53 & 18.0 & 23.4 & 13.1 &  330 & {\bf 15510} \\
\hline
\end{tabular}}
\medskip
Notes: $^{(1)}$~unit of $N({\rm H_2})$ is $10^{22}$~cm$^{-2}$; 
$^{(2)}$~this source was also observed in NH$_3$ by \citet{sridharan+2005}, with a better signal-to-noise ratio. We therefore use the kinetic temperature derived by this study rather
than our own data for this source;
$^{(3)}$~only the (1,~1)~transition of NH$_3$ is detected at this position, so that no kinetic temperature could be derived. A~temperature of 15~K has been assumed to compute masses and column density for this source. \\
When the distance ambiguity could be solved, the preferred distance and mass are shown in~boldface.
\end{table}