\begin{table}%t1
      \caption{Line parameters.}
         \label{line_parameters}
         \begin{tabular}{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}{S \sc{i} {\rm lines}}\\
            \noalign{\smallskip}
 8693.958  &   7.870  &    $-0.51^{{a}}$   &   \\ 
  8694.641  &   7.870  &    $0.08^{{a}}$  &  \\ % 
  9212.863  &   6.525  &    $0.43^{{b}}$   &   \\ 
  9228.093  &   6.525  &    $0.25^{{b}}$  &   \\ %
  9237.538  &   6.525  &    $0.03^{{b}}$  &    \\ 
          \hline
         \end{tabular}
\begin{list}{}{}
\item[$^{{a}}$] Line data taken from \citet{takeda}.
\item[$^{{b}}$] Line data taken from the {\sc nist} 
database.
\end{list}
   \end{table}