Colour-magnitude diagram of the epoch photometry for the BeT stars. The vertical brown line indicates the intrinsic colour, −0.05 mag, of early-type stars. The star plotted with dotted grey lines is discussed in Sect. 5.2. The model prediction from Granada et al. (2018) for B3 type stars is overplotted in two inclination angles (i = 18°, 84°), five n and eight ρ₀ (increasing from left to right; see the text for more details). The predictions with parameters that are unlikely to be obtained are plotted in grey. W1 mag of the predictions is shifted arbitrarily to match the observed magnitude range.