Single wavelength channel from the GPI H-band data of the HR 8799 system, post-processed with KLIP (left), PynPoint (centre) and Andromeda (right). The solid red circle denotes the position of HR 8799 e as computed using the pyKLIP astrometry module. Marked in red dashed lines are the regions which are compared when finding the mean correlation between different wavelength channels. At the top of the figure, histograms of the residuals are plotted in units of σ. The light blue line is a Gaussian fit with the width defined as the Gaussian standard deviation of the residual frame below.