Time extraction procedure applied pixel by pixel to event pixels and their surrounding QS pixels. Top row: intensity maps for five AIA bands (averaged over the temporal sequence) showing the event of Fig. 3a,d. The “event” region is identified by the black contour. Middle and bottom rows: Time lag and associated maximum correlation maps for five couples of AIA bands. These are the result of the pixel-by-pixel cross-correlation analysis. The maximum correlations of the events decreases as the intensities of the involved AIA channels decrease.