\begin{table}%t2
\par
\caption {\label{table:energies}Energy levels in Rydbergs for the $LS$ target states included in the calculation, relative to the \ion{Mg}{ix} 2s$^2~^1$S ground state.}
%%\centerline

 {
\begin{tabular}{rlrrr}
\hline\hline
  \multicolumn{2}{c}{}&\multicolumn{3}{c}{Energy in Rydbergs} \\
  \hline
  \multicolumn{2}{c}{$LS$ state} & \multicolumn{1}{c}{NIST$^a$} & \multicolumn{1}{c}{Current} & \multicolumn{1}{c}{B\&L$^b$} \\ 
\hline  
1  & 2s$^2~^1$S          &  0.0000 &  0.0000 & 0.0000 \\
2  & 2s2p~$^3$P$^{\rm o}$ &  1.3019 &  1.2877 & 1.3111 \\
3  & 2s2p~$^1$P$^{\rm o}$ &  2.4758 &  2.5292 & 2.5457 \\
4  & 2p$^2~^3$P          &  3.3555 &  3.3190 & 3.3956 \\
5  & 2p$^2~^1$D          &  3.6915 &  3.7066 & 3.7742 \\
6  & 2p$^2~^1$S          &  4.5530 &  4.5875 & 4.6851 \\
7  & 2s3s~$^3$S            & 13.9647 & 13.9390 & 13.9410 \\
8  & 2s3s~$^1$S            & 14.1983 & 14.1738 & 14.1800 \\
9  & 2s3p~$^1$P$^{\rm o}$  & 14.5220 & 14.4928 & 14.5096 \\
10 & 2s3p~$^3$P$^{\rm o}$  & 14.5575 & 14.5255 & 14.5377 \\
11 & 2s3d~$^3$D            & 14.8647 & 14.8696 & 14.8482 \\
12 & 2s3d~$^1$D            & 15.0776 & 15.0808 & 15.0878 \\
13 & 2p3s~$^3$P$^{\rm o}$  & 15.6064 & 15.5577 & 15.5980 \\
14 & 2p3s~$^1$P$^{\rm o}$  & 15.8837 & 15.8055 & 15.8453 \\
15 & 2p3p~$^1$P            & 15.9300 & 15.8824 & 15.9192 \\
16 & 2p3p~$^3$D            & 16.0149 & 15.9687 & 16.0069 \\
17 & 2p3p~$^3$S            & 16.1329 & 16.0867 & 16.1258 \\
18 & 2p3p~$^3$P            & 16.2160 & 16.1576 & 16.2127 \\
19 & 2p3d~$^1$D$^{\rm o}$  & 16.3084 & 16.2768 & 16.2968 \\
20 & 2p3d~$^3$F$^{\rm o}$  & \multicolumn{1}{c}{--} & 16.2910 & 16.2879 \\
21 & 2p3p~$^1$D            & 16.3652 & 16.3359 & 16.3892 \\
22 & 2p3d~$^3$D$^{\rm o}$  & 16.4777 & 16.4307 & 16.4704 \\
23 & 2p3d~$^3$P$^{\rm o}$  & 16.5460 & 16.5106 & 16.5421 \\
24 & 2p3p~$^1$S            & \multicolumn{1}{c}{--} & 16.6286 & 16.6815 \\
25 & 2p3d~$^1$F$^{\rm o}$  & 16.7189 & 16.7066 & 16.7492 \\
26 & 2p3d~$^1$P$^{\rm o}$  & 16.7815 & 16.7398 & 16.7998 \\
\hline
\end{tabular}}
\par
\smallskip
$^a$ NIST database \url{http://www.physics.nist.gov}; $^b$ \cite{bhatia}.
\end{table}