\begin{table}%t9
\caption{Observations of the Milky Way nucleus (from Fixsen et~al.~\cite{Fixsen99}), NGC~253 (from this paper), Henize~2-10 (from this paper) and the Cloverleaf~QSO (from Barvainis et~al.~\cite{Barvainis97}; Tsuboi et~al.~\cite{Tsuboi99}; Wei\ss\  et~al.~\cite{Weib03}).}\label{tab:comp}
%\begin{center}
\par
\begin{tabular}{c|cccc}
\hline
\hline
 $F$  & Milky Way & NGC~253 & Henize~2-10 & Cloverleaf\\
(W~m$^{-2}$)&&&&\\
\hline
CI($^{3}$P$_{1}$--$^{3}$P$_{0}$) &  $1.9\times 10^{-11}$ & $4.6\times 10^{-16}$ &  $3.8\times 10^{-18}$ & $1.7\times 10^{-23}$ \\
%\hline
CI($^{3}$P$_{2}$--$^{3}$P$_{1}$)  & $1.9\times 10^{-11}$& $4.0\times 10^{-16}$ & Not observed & $3.9\times 10^{-23}$\\
%\hline
\hline
$^{12}$CO(1--0)  & $2.7\times 10^{-12}$ & $2.0\times 10^{-17}$ & $4.8\times 10^{-19}$ & $\le$$1.5\times 10^{-24}$\\
%\hline
$^{12}$CO(2--1)  & $1.1\times 10^{-11}$ & $1.9\times 10^{-16}$ & $2.5\times 10^{-18}$ & \\
%\hline
$^{12}$CO(3--2) & $2.0\times 10^{-11}$ & $4.4\times 10^{-16}$ & $9.0\times 10^{-18~a}$ & $4.3\times 10^{-23}$ \\
%\hline
$^{12}$CO(4--3) & $3.0\times 10^{-11}$& $1.3\times 10^{-15}$ & $1.4\times 10^{-17}$ & $9.1\times 10^{-23}$ \\
%\hline
$^{12}$CO(5--4)  & $2.8\times 10^{-11}$ & $2.2\times 10^{-15~b}$ & $3.3\times 10^{-17~b}$ & $1.3\times 10^{-22}$\\
%\hline
$^{12}$CO(6--5)  & $2.0\times 10^{-11}$& $2.2\times 10^{-15}$ & $2.9\times 10^{-17}$ & \\
%\hline
$^{12}$CO(7--6)  & $1.7\times 10^{-11}$& $1.7\times 10^{-15}$ & $4.0\times 10^{-17}$ & $3.6\times 10^{-22}$\\
%\hline
$^{12}$CO(8--7)  & $1.9\times 10^{-11}$& $6.7\times 10^{-16~b}$
 & $4.9\times 10^{-17~b}$ &  \\
\hline
 \end{tabular}
%\end{center}
\par
$^{a}$~We chose to use $^{12}$CO(3--2) observations from Meier et~al.~(\cite{Meier01}) because they seem to agree with LVG and PDR~models (see Fig.~\ref{fig:modhe}) better than our observations.\\
$^{b}$~These values are computed from PDR~models.
\end{table}