\begin{table}%t11
\caption{Parameters used to determine the CO depletion factor: source Galactocentric 
distance ($D_{\rm GC}$), "expected'' \CIII\ abundance ($X_{\rm C^{17}O}^{\rm E}$), integrated 
intensity of \CIII\ at the dust peak position ($I({\rm C^{17}O}))$), beam filling factor
($\eta_{\nu}$), \CIII\ total column density ($N({\rm C^{17}O})$),
observed \CIII\ abundance ($X_{\rm C^{17}O}^{\rm O}$)
and CO depletion factor ($f_{\rm D}$).}\label{tab_dep}
 %\centering
\small
\begin{tabular}{cccccccc}
\hline \hline\\[-3mm]
Source & $D_{\rm GC}$ & $X_{\rm C^{17}O}^{\rm E}$ & $I({\rm C^{17}O}))$ & $\eta_{\nu}$ & $N({\rm C^{17}O})$ & $X_{\rm C^{17}O}^{\rm O}$ & $f_{\rm D}$ \\
       & (kpc)  &  ($\times 10^{-8}$) & (K \kms )  &  &  ($\times 10^{15}$\cmq ) & ($\times 10^{-8}$) &  \\
\hline
05345+3157 & 6.38 & 8.62 & 4.10 &  0.34         & 6.04 & 2.9 & 3.0 \\
05373+2349 & 6.96  & 7.38 & $\leq$2.38 & 0.62   & $\leq$1.99 & $\leq$0.9 & $\geq$8.2 \\
18144+3157 & 8.85  & 4.62 & 6.78 & 0.64         & 5.61  &  1.2 &  3.8 \\
18511+0146 & 11.5   & 2.56 & 12.84 & 0.93       & 7.73 & 6.0 & 0.4 \\
18517+0437 & 7.85  &  6.0  & 8.11 & 0.88        & 7.39 & 9.2 & 0.7 \\
19092+0841 & 5.64 &  10.6 & 9.46 & 0.72         & 9.03 &  3.3 & 3.2 \\
20126+4104 &  4.67  & 14.3 & 5.75 & 0.83         & 3.65 &  0.4  & 35.8 \\
20216+4107 &  7.47 & 6.47 & 7.13 & 0.62         & 5.93 & 3.2 & 2.0 \\
20343+4129 &  6.88 & 7.54 & 3.86 & 0.91         & 2.17 &  0.4 & 18.8 \\
22172+5549 &  9.42 & 4.05 & 2.39 & 0.83         & 1.45 &  0.5 & 8.1 \\
\hline
\end{tabular}
\end{table}