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tokens: on the neutron star. All MeerKAT observations were processed in a homogeneous way using PSRCHIVE. The first few days of Parkes and MeerKAT observations (see Figure 1 (b)) were used to improve the rotational ephemeris thereafter used to fold all MeerKAT observations. Radio frequency interference (RFI) was excised in a multi-step process: first, 10% of the recorded band was removed due to bandpass roll-off, yielding the nominal 900–1670 MHz MeerKAT L band; next, a mask with known persistent RFI signals (e.g., GSM, GPS) was applied to the data; finally, PSRCHIVE tools and clean.py, an RFI-excision script provided by the CoastGuard data analysis pipeline (Lazarus et al. 2016 ), were used to remove remaining RFI. More than 400 MHz of clean band was typically retained after this flagging. We summed all frequency channels, integrations, and polarizations for each observation to obtain total-intensity profiles. We then obtained times-of-arrival (TOAs) for each observation (i.e., two or three per day) by cross-correlating individual profiles with a standard template based on a very high signal-to-noise ratio observation. The same procedure was applied to MeerKAT observations of PSR J1644−4559. Using the TEMPO software we confirmed that the timing solution derived for PSR J1644−4559 was consistent with published parameters (see Manchester et al. 2005 ). Like many magnetars, PSR J1622–4950 displays unsteady rotation (e.g., Dib Kaspi 2014 ). Nevertheless, we were able to obtain a simple phase-connected timing solution for the three week period spanning the first two sets of paired Chandra and NuSTAR observations (Table 1 ), fitting the TOAs with TEMPO to a model containing only pulse phase, rotation frequency ( ν ), and frequency derivative (). This solution is presented in Table 2 . Over the five month span of all the radio timing observations presented here, the for PSR J1622–4950 changed by a factor of 7, and changed sign. In order to probe the evolution of the spin-down torque (), we fit short-term overlapping timing models where a fit for ν and proves adequate, i.e., with featureless timing residuals. Each of these short-term timing solutions spanned approximately one week. Figure 3 shows the run of from these solutions spanning five months. Figure 3. Time evolution of properties of PSR J1622–4950. Top panel: frequency derivative measured from short-term timing solutions (spanning horizontal error bars) obtained from MeerKAT data (see Section 3.3 ). Bottom panel: 0.3–10 keV absorbed X-ray flux as measured from the best-fit blackbody model (see Table 3 ). Swift observations are shown as open squares and combined Chandra and NuSTAR observations are represented simply by their error bars. The X-ray flux appears to be decaying exponentially with a time constant of 111 ± 19 days (see Section 4.4 ). All error bars represent 1 σ confidence levels. The gray band in both panels represents the timespan during which the X-ray outburst and radio revival most