Integrated flux vs. absolute value of relative difference in flux Δf_x, y, defined in Eq. (1). This is calculated for epochs 1 and 2 (blue circles), epochs 1 and 3 (pink diamonds), and epochs 2 and 3 (orange crosses). The scatter is larger than what could be expected in terms of rms noise error with median values of Δf_1, 2, Δf_1, 3, and Δf_2, 3 of 13.7%, 10.6%, and 8.9%, respectively.