\begin{table}%t7
\caption{\label{prod_co_tab}Abundance ratios in comet Hale-Bopp relative to carbon monoxide derived in this work and upper limits for the abundance
ratios relative to CO of solid acetylene and ethane in NGC
7538:IRS9 derived by \citet{1998AetA...331..749B}.}
%\centering
\par
\begin{tabular}{lcl}
\hline
\hline
\multicolumn{3}{l}{Hale-Bopp (this work):} \\
%\hline
$Q$(\CH22)/$Q$(CO) & = & 0.01 $\pm$ 0.001 \\
$Q$(\CH26)/$Q$(CO) & = & 0.03 $\pm$ 0.004\\
$Q$(\CH34)/$Q$(CO) & = & 0.008 $\pm$ 0.004 \\
\hline
\multicolumn{3}{l}{NGC 7538:IRS9 derived by \citet{1998AetA...331..749B}:}\\
$Q$(\CH22)/$Q$(CO) & $\le$ & 0.014  \\
$Q$(\CH26)/$Q$(CO) & $\le$ & 0.002 \\
\hline
\end{tabular}
\end{table}