Power spectra of one realisation for the FoCUS validation on mock data. The plots show EE spectra of the dust model (s_m in black), the noisy mock data (d_m in blue), and the FoCUS output ( in orange) for four masks with f_sky from 0.27 to 0.73. The red curve is the power spectrum of the residual map . The figure also presents the noise spectrum (n_m) and the noise estimate from FoCUS (), as well as cross spectra between half-mission mock maps (d_1,m × d₂,_m logarithmic binned) and between and d_m. Other mock data realisations show very consistent power spectra.