\begin{table}%t8
\caption{\label{tab:syserr}Summary of systematic and statistical uncertainties in the Sirius~B and
HZ~43A spectra.}
%\centerline
{ \begin{tabular}[t]{r|ccc|ccc|cccc|c}
 \hline
 \hline
 $\lambda$      &  $a$   &  $b$     &  $c$    &   $d$   &   $e$   &  $f$    &   $g$   &   $h$   &  $i$    &   $j$   &  $k$    \\
\hline
50              & 0.000 & 0.000 & 0.000 & 0.005 & 0.027 & 0.007 & 0.072 & 0.000 & 0.000 & 0.005 & 0.192 \\
60              & 0.001 & 0.000 & 0.001 & 0.002 & 0.014 & 0.007 & 0.011 & 0.002 & 0.000 & 0.005 & 0.122 \\
80              & 0.003 & 0.001 & 0.001 & 0.001 & 0.005 & 0.007 & 0.004 & 0.002 & 0.000 & 0.005 & 0.020 \\
100             & 0.005 & 0.001 & 0.001 & 0.000 & 0.003 & 0.007 & 0.002 & 0.004 & 0.000 & 0.005 & 0.018 \\
120             & 0.007 & 0.002 & 0.001 & 0.000 & 0.005 & 0.007 & 0.002 & 0.005 & 0.001 & 0.005 & 0.012 \\
140             & 0.010 & 0.004 & 0.002 & 0.000 & 0.006 & 0.007 & 0.002 & 0.005 & 0.002 & 0.005 & 0.010 \\
160             & 0.011 & 0.006 & 0.002 & 0.000 & 0.008 & 0.007 & 0.003 & 0.006 & 0.006 & 0.005 & 0.012 \\
170             & 0.012 & 0.007 & 0.002 & 0.000 & 0.010 & 0.007 & 0.051 & 0.008 & 0.010 & 0.005 & 0.031 \\
\hline
\multicolumn{1}{c|}{type}&
                    c   &   c   &   c   &   c   &   c   &   u   &   c   &   c   &   u   &   c   &   u   \\
\multicolumn{1}{c|}
{$\Delta\alpha$}& 0.010 & 0.006 & 0.001 & 0.003 & 0.022 & 0.006 & 0.008 & 0.005 & 0.007 & 0.000 & 0.027 \\
\multicolumn{1}{c|}
{$\Delta A$}    & 0.006 & 0.003 & 0.001 & 0.001 & 0.004 & 0.002 & 0.004 & 0.004 & 0.002 & 0.005 & 0.006 \\
\hline
\end{tabular}}
\par
 Interstellar absorption: \\
$^a$ Uncertainty in the absorption cross sections.
$^b$ Uncertainty in the ionisation correction.
$^c$ Neglect of metals in the opacity.\\
 Atmosphere modelling: \\
$^d$ Neglect of Compton scattering.
$^e$ Uncertainties in atmosphere models.
$^f$ Interpolation errors. \\
 Spectral extraction: \\
$^g$ Background uncertainty.
$^h$ Background contamination by source cross-dispersion distribution.
$^i$ Higher spectral order subtraction.
$^j$ Off-axis vignetting Sirius~B.
$^k$ Statistical uncertainty spectra. 
\end{table}