Left. Significance of the statistics at P = P _∗  ~ 18.6 ms, as a function of the lower end of the energy band, ϵ_l − 2.2 keV. The size of the extraction region is 18.85″. Right. Significance of the statistics as a function of the size of the extraction region, for energy band 0.36–2.2 keV. The confidence levels are given relative to the entire frequency range of the timing analysis.