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Update of the compliant coordinate system and User Interface Specification for CLAS

Mar.27,2026
National Space Policy Secretariat, Cabinet Office

The coordinate system of the Centimeter Level Augmentation Service (CLAS) will be updated from ITRF2014 (IGb14) based on the “Daily Coordinates of GEONET (F5 solution)” to ITRF2020 (IGb20) based on the “Daily Coordinates of GEONET (F5.1 solution)” published by the Geospatial Information Authority of Japan (GSI).

After the completion of this update, the positioning results for users of the CLAS will be the current coordinates on ITRF2020 (IGb20).

Before and after the update of the coordinate system, the positioning results of the users of the CLAS will move by the systematic difference (about 1 to 2 cm) between the F5 and F5.1 solutions, depending on the point, but there will be no suspension of the L6 signal due to this update.

- March 24, 2026 - March 27, 2026 (JST)

The User Interface Specification for the CLAS (IS-QZSS-L6) has been revised with this update. For the definition of the compliant coordinate system of the CLAS, please refer to the User Interface Specification.