Sample fits and residuals of three simulated systems from the iXX series. Top panel: folded light curves with grey points, with simulated transit curve samples for the first orbital period, including noise and pulsation with black circles. There are also the fits of the two models: the fixed angle, β = 0 model with blue dashed line, and the free angles, β = 0.25 model with orange solid line. The two fits are virtually indistinguishable on these graphs. Middle panel: residuals in the red noise case. Bottom panel: residuals in the white noise case. The colours along the horizontal line at y = 0 encode the sign of the difference between the predicted fluxes of the fixed angles (λ = 0, I_* = 90; at β = 0) and free angles (β = 0.25) models. Positive difference is shown in red, negative in blue; otherwise it is magenta.