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Information about the coordinate system used in the QZSS Positioning Navigation and Timing (PNT) service


The QZSS broadcast ephemeris and the public archive data on this website are based on the PNT coordinate system defined as below. This coordinate system is described as “JGS” (Japan satellite navigation Geodetic System) in the orbit products provided on this website.

  • Origin: Mass center of the earth
  • Z-axis: the IERS Reference north pole
  • X-axis: Intersection of the IERS Reference Meridian (IRM) and the equatorial plane
  • Y-axis: Completes a right-handed, Earth-centered, Earth-Fixed (ECEF) orthogonal coordinate system

The positions of monitor stations are managed by being applied the PNT reference coordinate system stipulated by IERS. The offset of the PNT reference coordinate system relative to ITRF should be within 2 cm (95%).

The history of the applied version of ITRF is as follows.

ITRF version Start date End date
ITRF2008 November 1, 2018 February 15, 2021
ITRF2014 February 15, 2021 November 9, 2023
ITRF2020 November 9, 2023 -