\begin{table}%t3
%\centering
\par
\caption{Finding the optimal DM2 conjugation altitude.\label{tab:best-h}}
%\centering
\par
\begin{tabular}{c|cc|cccc|cc}
\hline\hline
\multicolumn{1}{c|}{}&
\multicolumn{1}{c}{}&
\multicolumn{1}{c|}{}&
\multicolumn{1}{c}{$S_{\rm opt,1}$}&
\multicolumn{1}{c}{$S_{\rm opt,2}$}&
\multicolumn{1}{c}{$S_{\rm opt,3}$}&
\multicolumn{1}{c|}{$S_{\rm opt,4}$}&
\multicolumn{1}{c}{$S$}&
\multicolumn{1}{c}{$\varepsilon ~ (\%)$}\\
\multicolumn{1}{c|}{GS Configuration}&
\multicolumn{1}{c}{$h_{\rm max}$}&
\multicolumn{1}{c|}{$S_{\rm max}$}&
\multicolumn{1}{c}{(7.7 km)}&
\multicolumn{1}{c}{(6.7 km)}&
\multicolumn{1}{c}{(8.4 km)}&
\multicolumn{1}{c|}{(9.0 km)}&
\multicolumn{2}{c}{(8.0 km)}\\
\par
\hline 
3 NGS @ $30\arcsec $&
8.7&
0.61&
0.61&
0.60&
0.61&
0.61&
0.61&
--0.1\\
\par
3 NGS @ $45\arcsec $&
6.0&
0.43&
0.37&
0.41&
0.35&
0.30&
0.36&
--15.5\\
\par
5 NGS @ $45\arcsec $&
10.8&
0.55&
0.52&
0.51&
0.53&
0.54&
0.53&
--4.1\\
\par
4 NGS @ $45\arcsec $ + NGS&
10.1&
0.63&
0.62&
0.61&
0.63&
0.63&
0.62&
--1.8\\
\par
4 LGS @ $41\arcsec $ + NGS&
11.1&
0.57&
0.54&
0.53&
0.55&
0.56&
0.59&
--4.5\\
\par
4 LGS @ $56\arcsec $ + NGS&
10.2&
0.45&
0.43&
0.41&
0.44&
0.44&
0.43&
--3.6\\
\par
5 LGS @ $56\arcsec $ + NGS&
11.4&
0.47&
0.43&
0.42&
0.45&
0.45&
0.44&
--6.0\\
\par
Hybrid: 4 Na LGS &
9.3&
0.38&
0.37&
0.36&
0.38&
0.38&
0.37&
--1.8\\
\par
Hybrid: 5 Na LGS &
9.5&
0.40&
0.39&
0.38&
0.40&
0.40&
0.40&
--2.2\\
\hline
\end{tabular}
\end{table}