Flowchart of the spike detection algorithm: a) original cutout of the star; b) log-Polar transformed cutout. The dashed magenta lines indicate the division into four stripes of same size; c) median stacking of the stripes; d) radial profile of the median stripe; e) residual image obtained by first subtracting the radial profile from the median stripe and then dividing the result by the same radial profile; f) angular profile of the residual image, obtained by computing the median value along the radial axis. The magenta dashed line indicates the angular position of the spike.