\begin{table}%t6
 \caption{High velocity emission components of H I lines.}\label{tab6}
%\centering
\par
 \begin{tabular}{lrr}
 \hline  \hline
  & March 16 & March 17  \\
  & \multicolumn{2}{c}{(km s$^{-1}$)} \\ \hline
 H$\beta$ blue & --2460 & --2900  \\
 H$\beta$ red  & +2830  & +2830  \\
 H$\alpha$ blue & --2590 & --2860 \\
\hline
 \end{tabular}
\end{table}