\begin{table}%t1
 %\centering
\par
 \caption{\label{fabt:df54}Results (for the strongest triplet line at $777.2$~nm)
 obtained using our 54-level atomic model.  The non-LTE and LTE
 equivalent widths are given to show
 the sensitivity to various mechanisms.}
 \begin{tabular}{l|cc}
 \hline\hline
        & $W_{\rm non-LTE}$ & $W_{\rm LTE}$ \\
        & [m\AA]            & [m\AA]        \\
  \hline 
 $S_{\rm H}={\bf 0}$  &                   &   \\
standard case & 14.2   & 2.9   \\
\feh~$=-3.5$  & 10.9   & 1.0   \\
$\log~\epsilon_{\rm O}=6.0$  &  6.3   & 1.0   \\
% no $130$~nm                &  5.3 & 2.9 \\
% no $130$~nm, no $136$~nm   &  3.9 & 2.9 \\
% only 3s-3s e$^-$           &      &     \\
% no 3s-3s e$^-$             & 10.4 & 2.9 \\
% no 3s-3s e$^-$, 3s-3s H    & 15.0 & 2.9 \\
% old el. coll.              &      &     \\
% no backgr.                 & 19.9 & 2.9 \\
% no H Ly-$\beta$ opac.      & 16.9 & 2.9 \\
% Si*0.1                     & 24.6 & 2.9 \\
 \hline
$S_{\rm H}={\bf 1}$  &    &           \\
 standard case        &  6.7 & 2.9 \\
 \feh~$=-3.5$         &  4.2 & 1.0 \\
 $\log~\epsilon_{\rm O}=6.0$         &  2.9 & 1.0 \\
 no $130$~nm \Oi~ lines~                  &  3.9 & 2.9 \\
 no $130$~nm, no $136$~nm \Oi~ lines                   &  3.6 & 2.9 \\
 3s--3s Barklem e$^-$                       &  7.2 & 2.9 \\
 all Barklem e$^-$ but 3s--3s               &  6.5 & 2.9 \\
 no 3s--3s coupling                 &  5.2 & 2.9 \\
 old e$^-$ collisions                      &  6.2 & 2.9 \\
 old e$^-$ collisions, 3s--3s Barklem e$^-$ &  6.4 & 2.9 \\
 old e$^-$ collisions, no O+H 3s--3s  &  5.0 & 2.9 \\
 no UV background line opacity       &  7.8 & 2.9 \\
 no H Ly-$\beta$ opacity                &  6.8 & 2.9 \\
 Si*0.1                               &  9.4 & 2.9 \\
 \hline
 \end{tabular}
\end{table}