\begin{table}%t4
\caption{Parameters of shock excitation models.\label{tab4}}
%%\centerline
\par
{\begin{tabular}{lcccc}
\hline\hline  
Object & $v_{\rm s}$ & $n_{\rm H}^{a}$ & Age & Radiation field\\
\hline\\[-5pt]
& km s$^{-1}$ & cm$^{-3}$ & yr & \\
\hline
HH72A  & 31 & 10$^{4}$ & 185 & Yes\\
HH26A  & 52 & 10$^{4}$ & 70  & Yes\\
HH320A & 41 & 10$^{4}$ & 475 & No \\
HH25C$^{1}$ & 45 & 10$^{4}$ &  $>$260 & Yes \\
HH25C$^{2}$ & 27 & 10$^{5}$ &  $>$680 & Yes \\
\hline
\end{tabular}}
\par
\smallskip
Notes: $^{a}$$n_{\rm H} = n$(H) + 2$n$(H$_{2}$).\\
$^{1,2}$Models 1 and 2 of HH25C.
\end{table}