\begin{table}%t3
\caption{\label{tab:abspar}Adopted absorption parameters for Sirius~B and HZ~43A.
Numbers in brackets are derived from the basic numbers given in the other
entries of this table.} 
%\centerline
{\small 
\begin{tabular}{lcc}
\hline\hline
Ion       & Sirius~B & HZ~43A  \\
\hline\noalign{\smallskip}
\ion{H}{i}   column ($10^{22}$~m$^{-2}$)  & 0.58 $\pm$ 0.11  & 0.85 $\pm$ 0.06   \\
\ion{He}{i}  column ($10^{22}$~m$^{-2}$)  &(0.045 $\pm$ 0.010)& 0.057 $\pm$ 0.002  \\
\ion{He}{ii} column ($10^{22}$~m$^{-2}$)  &(0.017 $\pm$ 0.004)& 0.039 $\pm$ 0.012  \\
\ion{H}{i}/\ion{He}{i} &  12.8$\pm$1.4  &(14.9 $\pm$ 1.2)\\
\ion{He}{ii}/(\ion{He}{i}+\ion{He}{ii}) &0.27 $\pm$ 0.04 &(0.41 $\pm$ 0.08) \\
\hline
\end{tabular}}
\smallskip
\par
${{\rm a}}$ EUVE MW, \citet{holberg1998}.
${{\rm b}}$ EUVE LW, \citet{craig1997}.
${{\rm c}}$~HST-GHRS, \citet{hebrard1999}.
${{\rm d}}$ HST-STIS G430L, \citet{barstow2005}.
${{\rm e}}$ HST-STIS G750M, \citet{barstow2005}. 
\end{table}