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tokens: photons using 30′′ and 18 radius circular apertures, respectively. Table 1 Log of X-Ray Timing Observations of 1E 1207.4−5209 Notes. a Exposure times for XMM-Newton EPIC-pn does not reflect the 29% deadtime in the SmallWindow (sw) mode. b Newly reported observations. The NICER data sets are denoted by the ObsID and date of the first of the concatenated set of observations (see Section 2 for details). Table 2 Single Glitch Ephemerides for 1E 1207.4−5209 Notes. Derived parameters ( B s , , τ c ) are based on the pre-glitch timing solution. a Uncertainties in the last digits are given in parentheses. b Epoch of the glitch estimated by matching the zero phase of the two timing solutions; this assumes a constant post-glitch . The NICER (Gendreau Arzoumanian 2017 ) is an X-ray telescope attached to the International Space Station that provides submicrosecond time resolution in the 0.2–12 keV band. The NICER telescope consists of a set of 52 operational non-imaging silicon drift detectors (Prigozhin et al. 2016 ), each at the focus of an X-ray concentrator (Okajima et al. 2016 ) that subtends a 4′ radius field of view. The nominal effective area of the telescope is 1900 cm 2 at 1.5 keV. The NICER data sets were reduced and analyzed using the NICERDAD software suite distributed in the FTOOLS package, version 24Jun2019_V6.26.1, and the most up-to-date calibration files. We generated cleaned event files using the nicerl2 script that applied the standard filtering criteria. The data were further reduced by excluding detectors with anomalous count rates >5 σ above the mean rate, computed using all available detectors, in the energy range of interest. Similarly, we iteratively excluded time intervals with high background rates by comparing the event rate in 10 s steps to the mean rate. Since its launch in 2017, NICER has observed 1E 1207.4−5209 a total of 148 times to-date. Each observation is defined by a unique ObsID number and typically comprises short exposures (50% are less than 1.2 ks) spread over multiple satellite orbits, and often containing multi-day gaps within, and between. These exposures are generally too short to generate a precise pulse-phase measurement needed for our timing analysis. However, by concatenating adjacent observations we obtained eight sufficiently compact NICER data sets that contained the minimum number of events required to measure an independent pulse phase, as described below. 3. Timing Analysis For each reprocessed, cleaned event file, we folded the extracted photon arrival times on the pulsar frequency to compute the time-of-arrival (ToA) of phase zero of the pulse. To attempt a phase-connected timing solution, we fit the set of ToAs using the TEMPO software (Hobbs et al. 2006 ) to a model for the rotation phase of the pulsar including one or two of its frequency derivatives,Initially, we obtained the fold frequency from a periodogram search for the maximum power around the expected frequency, determined from the