\begin{table}%T1
\caption{Target levels of Ca XV and their threshold energies (in Ryd).}
\label{tab1}
%\centering
\par
\begin{tabular}{rllrr} 
\hline
\hline
Index  & Configuration & Level           &  Expt.$^a$ &GRASP$^b$ \\
\hline
  1 & 1s$^2$2s$^2$2p$^2$ & $^3$P$_0$	 &  0.0000 &  0.0000 \\
  2 & 1s$^2$2s$^2$2p$^2$ & $^3$P$_1$	 &  0.1600 &  0.1601 \\
  3 & 1s$^2$2s$^2$2p$^2$ & $^3$P$_2$	 &  0.3273 &  0.3281 \\
  4 & 1s$^2$2s$^2$2p$^2$ & $^1$D$_2$	 &  0.9896 &  1.0138 \\
  5 & 1s$^2$2s$^2$2p$^2$ & $^1$S$_0$	 &  1.8009 &  1.7695 \\
  6 & 1s$^2$2s2p$^3$ & $^5$S${_2}^{\rm o}$   &  2.4985 &  2.3928 \\
  7 & 1s$^2$2s2p$^3$ & $^3$D${_2}^{\rm o}$   &  4.5261 &  4.5364 \\
  8 & 1s$^2$2s2p$^3$ & $^3$D${_1}^{\rm o}$   &  4.5344 &  4.5456 \\
  9 & 1s$^2$2s2p$^3$ & $^3$D${_3}^{\rm o}$   &  4.5585 &  4.5677 \\
 10 & 1s$^2$2s2p$^3$ & $^3$P${_0}^{\rm o}$   &  5.3011 &  5.3144 \\
 11 & 1s$^2$2s2p$^3$ & $^3$P${_1}^{\rm o}$   &  5.3112 &  5.3246 \\
 12 & 1s$^2$2s2p$^3$ & $^3$P${_2}^{\rm o}$   &  5.3369 &  5.3500 \\
 13 & 1s$^2$2s2p$^3$ & $^3$S${_1}^{\rm o}$   &  6.6423 &  6.7940 \\
 14 & 1s$^2$2s2p$^3$ & $^1$D${_2}^{\rm o}$   &  6.6497 &  6.7971 \\
 15 & 1s$^2$2s2p$^3$ & $^1$P${_1}^{\rm o}$   &  7.4211 &  7.5695 \\
 16 & 1s$^2$2p$^4$ & $^3$P$_2$  	 & 10.0929 & 10.2321 \\
 17 & 1s$^2$2p$^4$ & $^3$P$_1$  	 & 10.3326 & 10.4681 \\
 18 & 1s$^2$2p$^4$ & $^3$P$_0$  	 & 10.3897 & 10.5269 \\
 19 & 1s$^2$2p$^4$ & $^1$D$_2$  	 & 10.8915 & 11.1048 \\
 20 & 1s$^2$2p$^4$ & $^1$S$_0$  	 & 12.3397 & 12.5692 \\
 21 & 1s$^2$2s$^2$2p3s & $^3$P${_0}^{\rm o}$ &  ...... & 37.4440 \\
 22 & 1s$^2$2s$^2$2p3s & $^3$P${_1}^{\rm o}$ &  ...... & 37.4905 \\
 23 & 1s$^2$2s$^2$2p3s & $^3$P${_2}^{\rm o}$ &  ...... & 37.7821 \\
 24 & 1s$^2$2s$^2$2p3s & $^1$P${_1}^{\rm o}$ &  ...... & 37.9481 \\
 25 & 1s$^2$2s$^2$2p3p & $^3$D$_1$	 &  ...... & 38.5909 \\
 26 & 1s$^2$2s$^2$2p3p & $^3$D$_2$	 &  ...... & 38.8009 \\
 27 & 1s$^2$2s$^2$2p3p & $^1$P$_1$	 &  ...... & 38.8099 \\
 28 & 1s$^2$2s$^2$2p3p & $^3$D$_3$	 &  ...... & 39.0419 \\
 29 & 1s$^2$2s$^2$2p3p & $^3$S$_1$	 &  ...... & 39.0900 \\
 30 & 1s$^2$2s$^2$2p3p & $^3$P$_0$	 &  ...... & 39.1045 \\
 31 & 1s$^2$2s$^2$2p3p & $^3$P$_1$	 &  ...... & 39.2720 \\
 32 & 1s$^2$2s$^2$2p3p & $^3$P$_2$	 &  ...... & 39.3384 \\
 33 & 1s$^2$2s$^2$2p3p & $^1$D$_2$	 &  ...... & 39.6112 \\
 34 & 1s$^2$2s$^2$2p3d & $^3$F${_2}^{\rm o}$ & 39.7586 & 39.9877 \\
 35 & 1s$^2$2s$^2$2p3p & $^1$S$_0$	 &  ...... & 40.0342 \\
 36 & 1s$^2$2s$^2$2p3d & $^3$F${_3}^{\rm o}$ & 39.9044 & 40.1271 \\
 37 & 1s$^2$2s$^2$2p3d & $^1$D${_2}^{\rm o}$ &  ...... & 40.1990 \\
 38 & 1s$^2$2s$^2$2p3d & $^3$F${_4}^{\rm o}$ &  ...... & 40.3352 \\
 39 & 1s$^2$2s$^2$2p3d & $^3$D${_1}^{\rm o}$ & 40.0866 & 40.3696 \\
 40 & 1s$^2$2s$^2$2p3d & $^3$D${_2}^{\rm o}$ & 40.2051 & 40.4639 \\
 41 & 1s$^2$2s$^2$2p3d & $^3$D${_3}^{\rm o}$ & 40.3327 & 40.5833 \\
 42 & 1s$^2$2s$^2$2p3d & $^3$P${_2}^{\rm o}$ & 40.4147 & 40.6537 \\
 43 & 1s$^2$2s$^2$2p3d & $^3$P${_1}^{\rm o}$ & 40.4147 & 40.6719 \\
 44 & 1s$^2$2s$^2$2p3d & $^3$P${_0}^{\rm o}$ &  ...... & 40.6853 \\
 45 & 1s$^2$2s$^2$2p3d & $^1$P${_1}^{\rm o}$ & 40.7610 & 41.0566 \\
 46 & 1s$^2$2s$^2$2p3d & $^1$F${_3}^{\rm o}$ & 40.7792 & 41.0685 \\
\hline
\end{tabular}
\begin{list}{}{}
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~$a$: Shirai et al (1990), 
%\ntd{$a$: Shirai et al (1990).}
%\ntd{$b$: Present results.}
\item $a$. Sugar \& Corliss (\cite{Sugar85}).
\item $b$. Aggarwal et al. (\cite{Aggarwal97}).
\end{list}
\end{table}