Time delay plot calculated from the phases of four different frequencies for all available observations by BRITE, bRing, ASTEP and TESS. Each color represents a frequency (ƒl, ƒ2, ƒ3, and ƒ4) listed in Table A.1. The blue lines indicate time delay predictions for β Pictoris b (dashed line), c (dashed, dotted line), and both planets (solid line). The lower panel is a zoom-in of the upper panel. The uncertainties in the time delays were derived from the covariance matrices given by the least-squares procedure, which was used in order to calculate the phases of the respective frequencies. The ticks at the top of the plot denote the various observatories: B 15, B 16, and B 17 for the BRITE observations in the years 2015, 2016, and 2017, respectively; A17 and A18 for the ASTEP observations in 2017 and 2018; and Rl and R2 for the first and second part of the bRing data.