Phase spirals and fitted spiral perturbations at different values for Galactic azimuth (ϕ) in the 2000 < L_Z/ kpc km s⁻¹ < 2200 range. The measured angle of the phase spiral is marked with a red line. The azimuthal range of the stars is marked with text in the right panels. This figure shows how we can use the model to determine the angle of the phase spiral, even in regions where the data are of lower quality due to extinction by dust.