Residuals obtained using the DDFWHE timing solution in Table 1. The residuals in blue, orange, green and red are derived from L-band/PUPPI data, P-band/PUPPI data, single GBT observation and FAST data. Top: Residuals as a function of time. Bottom: Residuals as a function of orbital phase. The post-fit residuals’ root mean square is consistent with the ToA uncertainties, and the RMS of the residuals from Arecibo L-band, Arecibo P-band, GBT and FAST are 66.088 μs, 87.709 μs, 138.936 μs and 13.581 μs, respectively. No unmodelled trends are seen in the ToA residuals, indicating that, within measurement uncertainty, the DDFWHE timing solution provides an adequate description of the timing of the system.