\begin{table}%t1
\caption{The values of the simplified  $D$ criterion.\label{tab1}}
$$\begin{array}{ccccc}
\hline\hline
\noalign{\smallskip}
{\rm Asteroid} &1997GL3&2000PG3&2002GM2&2002JC9\\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
1997GL3&0.00&0.26&0.09&0.17\\
2000PG3&0.26&0.00&0.30&0.13\\
2002GM2&0.09&0.30&0.00&0.18\\
2002JC9&0.17&0.13&0.18&0.00\\
\hline
\end{array}$$
\end{table}