Frequency analysis of the BHr 2015 data. Spectral window (panel a), original amplitude spectrum from 0 to 100 d⁻¹ (panel b), zoom into the original amplitude spectrum (panel c), and residual amplitude spectrum after prewhitening of the eight frequencies (panel d) with the residual noise level marked as horizontal dashed line. The triangles mark the frequencies found in the ASTEP data by Mékarnia et al. (2017). Vertical dashed lines mark the positions of the orbital frequencies of the BHr satellite and its multiples.