\begin{table}%t4
\caption{Flux scale factors for optical spectra.}
\label{tab4}
%\centering
\par
\begin{tabular}{c|ccc}
\hline
\hline
  Sample  &   Aperture &    Point-source & Extended source\\
  &       & scale factor & correction \\
&&$\varphi$ &$G$*\\
\hline
    L1 &     $4.2''\times 19.8''$&   1.000 &          0.000\\
    L1 &     $8.0''\times 19.8''$&   $1.089\pm 0.031$&    $0.84\pm
0.45$\\
    GH &     $2.5''\times 6.0''$&    $1.009\pm 0.021$&   $-2.76\pm
0.11$\\
    L&       $2.0''\times 6.0''$&    $1.036\pm 0.048$&   $3.85\pm
0.86$\\
\hline 
\multicolumn{4}{l}{*\rule{0pt}{11pt}  In units of
$10^{-15}$~erg~s$^{-1}$~cm$^{-2}$~\AA$^{-1}$.}\\
\end{tabular}
\end{table}