Point spread function from laboratory measurements performed during the CHEOPS on-ground calibration. Despite smoothing with a bilateral filter, the tails of the PSF measurement are affected by noise, and have therefore been replaced with a 1/r³ function for pixels below a threshold value. The image is normalised such that the sum over all pixels is 1. The field corresponds to 3.33 × 3.33 arcmin on the sky. The right plot shows a zoom on the central 100 × 100 pixels in 3D, illustrating more clearly the presence of spikes.