Changes to Ordnance Survey GNSS control networks and geoid models for Great Britain, Ireland and Northern Ireland

The three Ordnance Survey organisations have been working together to improve the OSGM02 geoid model resulting in OSGM15. OSGB has also updated the horizontal transformation OSTN02 to create OSTN15. The horizontal transformation polynomial for Ireland and Northern Ireland is unchanged.

OS Standard Logo Portrait CMYK

OSGB, OSI and OSNI will all switch to using the new systems on 26th August 2016. At the same time, all three organisations will switch to using updated coordinates for their GNSS control networks (active stations).

New active station coordinates
OSGB, OSI and OSNI will all implement the active station coordinate change on 26th August. OS RINEX data downloaded on or after that date will contain the new coordinates in the header, hence some customers may find small inconsistencies in the post processed coordinates of data observed before and after 26th August. RINEX data will not be available with the "old" active station coordinates after that date.

Leica Geosystems will also switch to using the updated station coordinates for the SmartNet real-time services and for the SpiderWeb services: RINEX data service, SmartRINEX data service and Point Computation service. Again, it is not possible for us to provide these services in both old and new coordinates so only the new coordinates will be used going forward.

New geoid models and new horizontal transformation for Britain
In Britain, OSGB has developed OSTN15 and OSGM15. Hence new Leica coordinate system files have been created (still based on the same ellipsoid and projection) for users to load into field kit and office software. The new coordinate system is called OSGB36(15) and can be downloaded from

In Ireland and Northern Ireland there is no new horizontal transformation, but there are 2 new geoid models relating to Malin Head and Belfast Lough. The new Leica geoid model files have been called OSGM15RoI and OSGM15NI respectively. New coordinate systems have been created and can be downloaded from


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