\begin{table}
%\centering
\par
\caption{Summary of groove parameters from observations.}
\label{tab01}
\begin{tabular}{llllll}
\hline\hline
\noalign{\smallskip}
date    & range N & range S & center & depth N & depth S\\[0.5ex]
\noalign{\smallskip}
\hline
\noalign{\smallskip}
1996.43 & $25.1$  & $-33.0$ & $-7.0$   & $1.37$  & $1.23$ \\
1996.93 & $28.7$  & $-39.2$ & $-8.0$   & $1.31$  & $1.25$ \\
1997.43 & $28.9$  & $-35.7$ & $-6.0$   & $1.39$  & $1.25$ \\
1997.93 & $29.4$  & $-39.9$ & $-8.0$   & $1.41$  & $1.26$ \\
1998.43 & $40.4$  & $-38.4$ & $-1.0$   & $1.29$  & $1.22$ \\
1998.93 & $41.3$  & $-47.4$ & $-9.0$   & $1.40$  & $1.24$ \\
1999.43 & $44.1$  & $-62.0$ & $-33.0$  &         &      \\
1999.93 & $34.9$  & $-61.2$ & $-24.0$  &         &       \\
\hline
\end{tabular}
\end{table}