Stability analysis of core payload operational performance on the XPNAV-1 satellite

A carefully engineered focusing X-ray pulsar telescope (FXPT) is the main payload of China’s first X-ray pulsar navigation test satellite XPNAV-1. Factors such as launch vibrations, space radiation, and device lifespan can cause slight variations in the performance parameters of the FXPT. Therefore, long-term monitoring of its performance is necessary to provide more reliable observational data for astronomical timing analysis and navigation calculations. To monitor the performance changes of the FXPT on the XPNAV-1 satellite, a comprehensive analysis method combining the statistical distribution of photon count rates and the characteristics of pulse profile shapes was proposed. Using observation data of the Crab pulsar from 2016 to 2019 obtained by the XPNAV-1 satellite, the in-orbit operational stability of the FXPT was analyzed. The results show that the statistical distribution of the Crab pulsar photon count rates obtained by the FXPT approximately follows a Gaussian distribution. Even with a few periods of anomalous count rates, the pulse profile shapes still exhibit high similarity over different periods. High signal-to-noise ratio pulse profiles that are 99.99% comparable to pulse profiles folded using the ephemeris supplied by Jodrell Bank Observatory can be produced by the timing model generated from FXPT data. These results confirm the in-orbit operational stability of XPNAV-1’s core payload, the FXPT.