\begin{table}%t3
  %\centering
\par
  \caption{\label{tab_pred}Predicted hyperfine frequencies of the $J_K = 1_0
 \leftarrow 0_0$ transition of NH$_3$.}
 $$\scriptsize
  \begin{tabular}{D{,}{-}{1}D{,}{,~}{3}D{.}{.}{4}D{.}{.}{3}}
    \hline\hline \\[-2ex]
    F'_{\rm N},F_{\rm N}& F' & \mcl{1}{c}{Frequency} & \mcl{1}{c}{Line strength} \\
     & & \mcl{1}{c}{(MHz)} \\
    \hline  
      1,1           &  2.5   &  572~497.1220  & 2.000 \\
      \mcl{1}{c}{}  &  1.5   &  572~497.1286  & 1.333 \\
      \mcl{1}{c}{}  &  0.5   &  572~497.1573  & 0.667 \\
      2,1           &  3.5   &  572~498.3387  & 2.667 \\
      \mcl{1}{c}{}  &  2.5   &  572~498.3869  & 2.000 \\
      \mcl{1}{c}{}  &  0.5   &  572~498.3989  & 0.667 \\
      \mcl{1}{c}{}  &  1.5   &  572~498.3992  & 1.333 \\
      0,1           &  1.5   &  572~500.1914  & 1.333 \\ 
    \hline
  \end{tabular}
  $$
\end{table}