\begin{table}%t3
%\centering
\par
\caption {\label{tabres2L}Accuracy $\delta L /L$ on luminosity determination, for a frequency accuracy of 0.2~$\mu$Hz, obtained from different methods of evaluating spectra difference and for different values of considered modes.} 
\begin{tabular}{cccc} 
\hline\hline
Nf of modes  & 20 & 40 & 60 \\
\hline
 $\delta L /L$  with $\delta \nu$ & 0.06 & 0.04 & 0.02\\
$\delta L /L$  with $\delta_{\rm sls}$ &  0.1 & 0.05 & 0.05\\
\hline
\end{tabular}
 \end{table}