\begin{table}
% \begin{minipage}[t]{\columnwidth}
% \caption{Upper Bounds on Total Ammonia Column Densities
% $\langle N(NH_3) \rangle_{\rm max}$ [10$^{12}$ cm$^{-2}$]}
% \label{obs_table_sum}
% %\centering
\par
% \renewcommand{\footnoterule}{}  % to avoid a line before footnotes
% \begin{tabular}{cccccc}
% \hline 
%  & & & & &  \\[-3mm]
%  line & $n(J,J)$\footnote[1]{defined in Eq.~(\ref{njj})} & C/2001 A2-B & C/2002 C1  &  C/2001 Q4 &  C/2002 T7 \\[1mm]
%  (J,J) &                                            & (LINEAR)   & (Ikeya-Zhang) &  (NEAT)    &   (LINEAR) \\[1mm]
% \hline 
%   & & &  & & \\[-3mm]
% (1,1) & 0.26 & 3.7 & 3.3 & 5.5  & 7.5 \\
% (2,2) & 0.18 & 2.4 & 2.6 & 6.3  & 8.1 \\
% (3,3) & 0.20 & 2.0 & 3.1 & 4.9  & 6.3 \\
% (4,4) & 0.05 & 7.6 & 3.0 & 22.6 & 39.5 \\
%              & 1.9 & 1.5 & 3.1  & 4.1 \\
% \multicolumn{2}{c}{Total}     
%   & & &  & & \\[-3mm]
% \hline
% \end{tabular}
% 
% \end{minipage}
% \end{table}