Service Notifications

Service Notifications

Update to ITRF2014 of TerraStar correction services

Update to ITRF2014 of TerraStar correction services

On Tuesday 12th September 2017 TerraStar will update the reference frame in which its correction services are provided, transitioning from ITRF2008 to ITR2014. The effect on users of PPP solutions using TerraStar corrections is positions will be output in ITRF2014 rather than ITRF2008 coordinates. The resulting change in coordinates will be at the several mm-level.


ITRF2014 is the new realisation of the International Terrestrial Reference System (ITRS). The ITRS defines an international, geocentric, reference frame suitable for use with measurements on or near the Earth's surface. This reference system is periodically updated by the International Earth Rotation Service (IERS), resulting in an ITRF realisation. The reason for these updates is that the Earth is continually changing in shape and global tracking networks of space observation equipment continually provide more and improved observation information. Based on completely reprocessed solutions of the several space observation techniques, the ITRF2014 is expected to be an improved solution compared to ITRF2008.


ITRF2014 was introduced in January 2016, see: http://itrf.ensg.ign.fr/ITRF_solutions/2014/
In order for TerraStar PPP services to enable users to position in the best and latest available reference frame, TerraStar will adopt the latest ITRF realisation, ITRF2014.


The transformation between these two ITRF realisations is described by a 7 parameter shift, consisting of 3 translations, 3 rotations and 1 scale factor. The change from ITRF2008 to ITRF2014 is small, in the order of 4mm, as shown by the transformation parameter values below:
• Translation in X-coordinate: 1.6mm
• Translation in Y-coordinate: 1.9mm
• Translation in Z-coordinate: 2.4mm
• Rotation around X-axis: 0
• Rotation around Y- axis: 0
• Rotation around Z- axis: 0
• Scale: -0.02 parts per billion
Given that the shift of ~4mm is very small relative to the accuracy of PPP solutions this transition from ITRF2008 to ITRF2014 will not cause a noticeable step change in the positions output from receivers using TerraStar products, and as such users are not required to change the use or interpretation of the position information during or following this change.