Contamination of exomoon transits by transits of the host planet. In the numerical simulations, a Jupiter-sized planet with a Ganymede-sized test moon was simulated to transit a Sun-like star with b = 0. (a) Percentage of an exomoon’s in-transit data that is not contaminated by planetary transits. The black curve shows the mean value of u after 10 000 numerical simulations for each planet-moon distance. The gray shading represents the standard deviation. The white solid and white dotted lines illustrate the analytical expressions as per Eq. (3) for b = 0 and b = 0.5, respectively.(b) The square root of the data shown in panel a estimates the S/N preservation of the exomoon transits upon rejecting any data during planetary transits. The measurement by K21 for a simulated system with 24 transits (using b = 0.5) is labeled “K21”.