Distributions of ΔT_b of observational brightening events from Eklund et al. (2020) with their corrected ΔT_b according to Eq. (3) and Fig. 8. (a) The events observed within the INW regions (dashed blue) along with the estimated distribution using the values for QS region derived here (solid blue), with bars showing ±1σ for each bin. (b) The observed events in the NW regions (dashed red) and the corrected distribution using the values for the FS region, with the indications of ±1σ for each bin.