\begin{table}%t3
%\centering
\par
      \caption{Line parameters.\label{line_parameters}}
              $$
         \begin{array}{rrrrr}
            \hline\hline
            \noalign{\smallskip}
        {\rm Wavelength }     & {E_{\rm exc}} &  {\log~gf}  \\ 
            \noalign{\smallskip}
           {\rm (\AA )} &  {\rm (eV)} &     {\rm (cgs)} \\
           \noalign{\smallskip}
              \hline
           \noalign{\smallskip}
            \multicolumn{3}{l}{ \hbox{\rm S \sc{i}~ lines}}\\
            \noalign{\smallskip}
 % 8693.958  &   7.870  &   -0.510   &   \\ %2.50 & 1.00E+07 \\
 % 8694.641  &   7.870  &    0.080   &  \\% 2.50 & 1.00E+07 \\
  9212.863  &   6.525  &    0.43^{{a}}   &   \\ % 2.50 & 2.95E+07 \\
  9228.093  &   6.525  &    0.25^{{a}}  &   \\ % 2.50 & 2.88E+07 \\
  9237.538  &   6.525  &    0.04^{{a}}  &    \\ %2.50 & 2.88E+07 \\
          \hline
            \noalign{\smallskip}
            \multicolumn{3}{l}{ \hbox{\rm Fe \sc{ii} ~lines}}\\
            \noalign{\smallskip}
\par
  4416.830  &  2.778  &  -2.80^{{b}}  &  \\ %  2.50 & 4.112E+08 \\
  5264.812  &  3.230  &  -3.19^{{b}}  &   \\ % 2.50 & 4.112E+08 \\
  5284.109  &  2.891  &  -3.29^{{b}}  &   \\ % 2.50 & 3.428E+08 \\
  6149.258  &  3.889  &  -2.82^{{b}}  &    \\ %2.50 & 3.388E+08 \\
  6432.680  &  2.891  &  -3.67^{{c}}  &   \\ % 2.50 & 2.897E+08 \\
  6456.383  &  3.903  &  -2.25^{{c}}  &   \\ % 2.50 & 3.373E+08 \\
            \noalign{\smallskip}
            \hline
           \noalign{\smallskip}
         \end{array}
     $$
   \end{table}