Periodograms for P₂ computed separately for three datasets (DESCAMPS, SPHERE2017, SPHERE2018). The value was optimised for the first dataset and then only P₂ was varied. We show the old incorrect period (dotted line) together with an expected spacing between local minima given by the time-span ΔP = P₂∕(t₂ − t₁), and the new correct one (grey line). The shift of P₂ for SPHERE2017 and an increased χ² for SPHERE2018 were present because of incorrect identification of the two moons; this was corrected after computing the periodograms and before fitting the orbits.