Impact parameter as a function of time. Doppler tomographic measurements (from Watanabe et al. 2022) are shown in dark blue, previously published photometric measurements are shown in green, with the two at the same epoch taken from Dholakia et al. (2022) (light green) and Kálmán et al. (2022) (dark green). Our CHEOPS measurements are shown in dark red, with the result from the fit to all four transits indicated by a square, and the fits to each pair of transits by circles. The epochs of our four CHEOPS transits are shown with short red vertical lines just above the abscissa. The solid black line is the nodal precession model presented in Watanabe et al. (2022).