\begin{table}%t5
\caption{OH comet observations, Nan\c{c}ay RT and MPIfR, May 2004.\label{OH_compare}}
%\centerline
{\begin{tabular}{cccc}
\hline\hline
May date &  Line area $^a$ &  Line area $^b$ & Line area $^c$  \\
&LTE &LTE &1667 only\\
 & [mJy~km s$^{-1}$] & [mJy~km s$^{-1}$]& [mJy~km s$^{-1}$] \\
\hline
% & &   \\[-3mm]
\multicolumn{4}{l}{Comet C/2001 Q4 (NEAT)}  \\ 
16 &  104~$\pm$~12 & no obs. & no obs.\\
17 &  101~$\pm$~12 & 65--207 &  130~$\pm$~31  \\
18 &  75~$\pm$~12  & no obs. & no obs.\\
%  & &  \\[-3mm]
\multicolumn{4}{l}{Comet C/2002 T7 (LINEAR)}  \\
16 &  176~$\pm$~12 & no obs. & no obs.\\
17 &  no obs.    & $229\pm28$      & 203~$\pm$~39  \\
18 &  185~$\pm$~16 & no obs. & no obs.\\
\hline
\end{tabular}}
\par
\smallskip
$^a$ {Nan\c{c}ay RT, mean of 1665~MHz and 1667~MHz lines assuming LTE ratio of 5:9.}\\
$^b$ {MPIfR, mean of 1665~MHz and 1667~MHz lines assuming LTE ratio of 5:9.  The range for C/2001 Q4 assuming the 1665~MHz line amplitude lies between 0 and its 3$\sigma$ upper limit.}\\
$^c$ {MPIfR, 1667~MHz detection only.}
\end{table}