\begin{table}%t3
%\centering
\par
\caption{\label{tab:sixth}Fit results in the search for the 6th harmonic using
the cut-off power law model for the continuum above 13~keV.
$\Delta\chi^2$ is referred to the introduction of the further Gaussian
absorption line. $E_{\rm abs}$ is the centroid value, $E_{\rm B}$ is the
value corresponding to three times the centroid energy of the second
harmonic, and $N_{\rm abs}$ is the line normalization. The null
hypothesis probability is obtained using the F-test.}
\small \begin{tabular}{l c c}
\hline \hline
Phase                        & 0.33--0.40                  & 0.40--0.46              \\
\hline
$E_{\rm abs}$ [keV]         & $71\pm3 $                   & $68.6\pm2.6$              \\
$E_{\rm B}$ [keV]                  & $66.9\pm0.3$                & $70.74\pm0.15$             \\
$N_{\rm abs}$ [keV]         & $4.5\pm2.5$                 & $3.1_{-0.6}^{+1.3}$         \\
$\Delta\chi^2{\rm (d.o.f.)}$&$221(168)\rightarrow215(166)$&$158(142)\rightarrow152(140)$ \\
Null hypothesis probability  &  10\%                       & 5\%                           \\
\hline
\end{tabular}
\end{table}