\begin{table}%t4
%\centering
\par
\caption{ISM molecular and atomic column densities toward HD207538.\label{ism_ab}}
\begin{tabular} {cc}
\hline
\hline
Species & $\log N \rm (dex)$ \\
\hline
Ar{\sc i}   & $\rm 16.45^{+.25}_{-.50}$ \\
CO	    & $>$15.00 \\
Cl {\sc i}  & $\rm 14.4^{+.80}_{-.90}$\\
Fe {\sc ii} & $\rm 14.80^{+.10}_{-.10}$ \\
H {\sc i}   & $21.34 \pm 0.12$\\
H20         & $20.64 \pm 0.07$\\
H21	    & $20.58 \pm 0.05$\\
H22	    & $\rm 18.75^{+.10}_{-.15}$\\
H23	    & $\rm 17.95^{+.25}_{-.20}$\\
H24	    & $\rm 17.60^{+.40}_{-.60}$ \\
H25	    & $\rm 15.95^{+1.05}_{-2.0}$ \\
H26	    & $>$14.00 \\
H27	    & $>$14.00 \\
HD	    & $15.86 \pm0.35$\\
N {\sc i}   & $17.2 \pm 0.5$ \\ 
Na {\sc i}  & $>$14.72 \\ 
O {\sc i}   & $\rm 17.80^{+.35}_{-.35}$ \\
P {\sc ii}  & $13.00\ll 14.60$ \\
\hline
\end{tabular}
\end{table}