Multiresolution adaptive grid. The number density of grid points (shown as 891 red crosses) traces a smooth version of the solution in the spectroscopic lens model, increasing the resolution in the densest regions. Ten additional grid points are shown as small black crosses. Two of them mark the perturbers in the La Flaca arc with scales of 012 and 024, and eight more are in the inner region of the Anzuelo arc. Each one of these 8 grid points has a scale of 18.