\begin{table}%t1
\caption{Underlying jet and shock parameters.}\label{tab1}
%\centering
\par
\begin{tabular}{lllll}
\hline\hline
Underlying&P1&&&P2\\
jet &shock1&shock2&shock3&shock4\\ 
\hline  
$B=60$ mG&$B=98$ mG&$B=40$ mG&$B=5$ mG&$32.5$ mG\\
$D=5$&$D=10$&$D=10$&$D=19$&$D=10$\\
 &$\gamma_{b}=530$&$\gamma_{b}=3100$&$\gamma_{b}=100000$&$\gamma_{b}=4700$\\
 \hline
\end{tabular}
\end{table}