Figure 1. Recent pulse profiles (top) compared to those immediately before (bottom) and after (middle) the shape change at each observing band. The GBT profiles are based on individual 20-30 minute observations, while the CHIME profiles are averaged over the six-week periods immediately preceding and following the date of the shape change (MJD 59321) and immediately preceding 2022 January 10 (MJD 59589).

Figure 2. Profile residuals in the period between 2019 March 17 (MJD 58559) and 2022 January 10 (MJD 59589). To produce this figure, a scaled and shifted copy of a template, derived from the average pulse shape before the shape change, was fit to each pulse profile. A distinct template was used for each observing band. Profiles were then shifted to align them with the template according to the best-fit shift, and the appropriately-scaled template was subtracted. The abrupt change in pulse shape at 2021 April 17 (MJD 59321) is immediately noticeable. Also apparent is the gradual reduction in the amplitude of the profile residual at each frequency band over the succeeding months, which indicates that the profile is recovering toward its previous shape.