Frequency versus time of arrival plot of two bursts (grey scale) in polar-cap geometry overlaid with the two bursts observed from the Galactic magnetar SGR J1935+2154 by CHIME/FRB (extracted from Fig. 1 of Andersen et al. 2020). As in the CHIME/FRB observation, the two bursts are separated by 29 ms, and the frequency range has been restricted to f/f₀ ∈ [0.4, 0.8], which can be immediately scaled to the 400–800 MHz bandwidth of the telescope (right-hand-side vertical axis). The second burst has a 25% larger photon rate , and they have the same Gaussian width σ_i = 0.5 ms and Gaussian opening angle . Other fiducial parameters are the same as in Fig. 4 for the envelope at colatitude i − α_o/2 and longitude α_o: P = 3245 ms (period of SGR J1935+2154), Ω = α_o/5 ≃ 0.020 rad, β = 3. Line styles for the envelope are as in Fig. 4.