Light-curve analysis pipeline. Panel a: section of the original frame. Panel b: differential image for that frame, i.e., the current frame minus the reference image. Panel c: circular mask around the mean location of the impact. Panel d: circular mask within a smaller radius containing all the light from the impact and recentered on the impact. Seeing distorts each image differently, and the location of the flash needs to be adjusted frame by frame by the software. The example is from the S.P. video observation on 2017-05-26.