Flagship footprint and area rescaling subregions. Left: bootstrap subregions, indicated with different colours, that are used to calculate errors in YAW. Right: different subregions of the Flagship footprint, shown with different colours, used to establish the relation between the tracer–target overlap area and the uncertainty on the mean redshifts of tomographic bins. The four subpanels show the Flagship footprint divided into 2 (top left), 4 (top right), 8 (bottom left), and 16 (bottom right) subregions. These are plotted on an orthographic projection of a subset of the sky focused on the Flagship footprint. The RA and Dec grid is shown with dashed grey lines. The values of the grid lines are indicated where they intercept the x-axis for the RA grid and the y-axis for the Dec grid.