Schematic of the flat-topped triangular function used to parameterize the PSF spokes. The blue spoking function is constructed such that the red and the green areas exactly cancel out. The dashed line shows the unspoked function. The lengths 1.00, 0.165 (the half-width of the flat-top u) and 0.165 (the base to peak width v) are in units of half the inter-spoke distance, i.e., 11.25°. The figure is not to scale.