Distribution of O4 (left-hand panel) and O5 (right-hand panel) KN g band (484 nm, upper panel in blue) and J band (1250 nm, lower panel in red) magnitudes as a function of time. The shaded regions show the apparent AB magnitude versus post-merger time for 50%, 90%, and 99% of our simulated KN light curves GW-detectable sources. Colored circles show extinction-corrected AT2017gfo data rescaled to the median distance of the GW triggers (∼212 Mpc in O4, ∼381 Mpc in O5). The solid, dashed and dotted lines show the cumulative distributions of apparent magnitude at peak, at 3 days and at 5 days after the merger, respectively.