Face-on view of the Galactic centre. The negative direction along the z-axis points towards Earth. The red star marks the position of Sgr A^⋆. The black dots show the best-fit positions for the bright clumps Sgr C1, C2, C4 (Table 3), and Sgr B2 (Walls et al. 2016) in the solar-metallicity and uniform density profile case. The grey parabolas trace the best-fit associated wavefronts (as seen from Earth; Sunyaev & Chuarzov 1998) for the two-event model. The width of the parabolas represents the statistical uncertainty on the position, not the duration of the associated event.