Maps of G31 first-order (color scale) and zeroth-order moment (contours) for the ammonia inversion transitions (2, 2) to (6, 6) (Mayen-Gijon et al. 2014). The color scale, the same for all panels, ranges from 94 to 101 km s⁻¹. The contours are in steps of 10% of the peak value for all the maps, except for the (4, 4) transition, for which the steps are 20%. The beam is shown in the lower right corner of each panel.