Individual steps in the construction of the arc geometry defined by α = π/4, φ = 0, and Δ ≈ 22 Mm. Left: unit Gaussian annulus with the radius Δ and the given FWHM. Middle: weighted angle interval ⟨φ−α/2;φ+α/2⟩. Right: resulting one-sided arc averaging geometry. The black dots indicate the central points and are not parts of the averaging geometries. For display purposes, the FWHM of the Gaussian annulus was enlarged.