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tokens: is as follows. The observations and data are described in Section 2 , the methods of analysis are described in Section 3 , and the results are discussed in Section 4 . 2. Observations The X-Ray Pulsar Navigation -I ( XPNAV -1) satellite is the first mission operated by the China Academy of Space Technology to demonstrate navigation using X-ray pulsars. This small (270 kg) satellite was launched on 2016 November 10, by the Long March 11 rocket at the Jiuquan satellite launch centre to the 500 km LEO orbit. It operates in the three-axis stabilization mode with the ability to quickly point to any inertial position with an accuracy within 2 arcmin according to demand, and to provide up to 90 minutes sustained observation on any target (see Zhang et al. 2017 ; Huang et al. 2018a ). The X-ray instrument used for this Crab pulsar glitch observation is the time-resolved soft X-ray spectrometer (TSXS). This instrument uses a grazing incidence focusing lens composed of four nested mirror shells with a collecting area of 30 cm 2 to focus X-ray photons within a 15 arcmin field-of-view onto a silicon drift detector. The effective detecting area of the instrument is 2.4 cm 2 at 1.5 keV. A GPS-calibrated Rb clock is included to provide accurate timing and a quasi-parallel optical star is used to assist the inertial pointing. The TSXS has the ability to provide 1.5 μ s time resolution. The observations used in this work were obtained from the period between UTC 2017 October 10 and 2018 April 28. A total of 627 observations of duration more than 1500 s were selected. Of these observations, 71 were collected pre-glitch, and 556 post-glitch. 3. Data Processing 3.1. Data Analysis Software System for XPNAV-1 The X-ray data are processed by the Data Analysis Software System (DASS; Zhang et al. 2017 ), which is illustrated in Figure 1 . Figure 1. Data flow of the Data Analysis Software System (see Zhang et al. 2017 ). In the DASS, data from XPNAV -1 are first unpacked to extract the GPS data, the satellite attitude data, the satellite status flag data, and the X-ray photon data. Then the X-ray photons are selected as described by Huang et al. ( 2018a ). The top-level timing formula is based on Edwards et al. ( 2006 , Equation (7)). The timescale transformation from the local time to the barycentric coordinate time and the time delays associated with the Earth’s and satellite’s orbital motion are considered, so that the Roemer delay, the Shapiro delay, the parallax delay, the Einstein delay, and the vacuum propagation delay are calculated to correct the photon arrival time at the satellite to that at the solar system barycenter (SSB) (see Edwards et al. 2006 ; Hobbs et al. 2006 ). The satellite position at each single photon’s arrival time is propagated from the on-board GPS data. With the photon arrival time at the SSB, we fold the pulse profiles into 256 bins per period. Pulse times of arrival (TOAs) are calculated by cross-correlation between the folded profile