\begin{table}%T3
%\centering
\par
\caption{Adopted parameters of the \MHI\ vs. diameter relation.}
   \label{t3}
\begin{tabular}{ccc}
\hline\hline
Type & $a$ & $b$  \\ 
\hline
Sa-Sab     & 7.17 & 1.64\\ 
Sb         & 7.29 & 1.66\\ 
Sbc        & 7.27 & 1.70\\ 
Sc         & 6.91 & 1.90\\ 
Scd-Im-BCD & 7.00 & 1.88\\
\hline
   \end{tabular}
   \setcounter{table}{3}
   \end{table}