A method of ground target positioning by observing radio pulsars

We use radio millisecond pulsars (MSPs) to determine the position of the Parkes telescope to explore the feasibility of pulsar navigation for terrestrial application, as well to investigate the relations between pulsar observations and the positional errors for potential X-ray pulsar navigation (XNAV). Different from the analytical algorithm (Han et al. Astrophys. Space Sci. 364, 3, 2018) which derives the relations between observatory coordinates and pulsar timing residuals, a grid search method is used in our work. The method divides the space adjacent to the radio telescope into small grids, from which we form the rms timing residuals and fit pulsar parameters to find the position with minimal χ2 value. Six pulsars from the Parkes Pulsar Timing Array (PPTA) are selected to perform position determinations. The positional errors are analyzed together with the pulsar reference phase, timing residuals, and observation numbers. Using a hybrid database of pulsar timing and cartographic data, we obtained best positional accuracy of around 10 m by PSR J0437 − 4715. To investigate the feasibility of pulsar terrestrial navigation, only few observations from PSR J0437 − 4715 are used for position determinations. The results show that the precision of about 100 m is achievable with only 3 or 4 observations. In this paper, we introduce our method in detail and discuss the positioning performance in different scenarios.