Geocentric Datum of Australia (GDA)

The Geocentric Datum of Australia (GDA) is the latest Australian coordinate system, replacing the Australian Geodetic Datum (AGD).

The GDA is a part of a global coordinate reference frame and is directly compatible with the Global Navigation Satellite Systems (GNSS).

It is the result of more than a decade of anticipation and work by the Intergovernmental Committee on Surveying and Mapping (ICSM) and its predecessor, the National Mapping Council (NMC).

When the NMC adopted the Australian Geodetic Datum (AGD84) coordinate set in 1984, it recognised the need for Australia to eventually adopt a geocentric datum. This was further recognised in 1988 when the ICSM recommended the adoption of an appropriate geocentric datum by 1 January 2000. This resulted in the adoption of the GDA94.

GDA94 specifications

  • Datum: Geocentric Datum of Australia (GDA)
  • Geographical coordinate set: Geocentric Datum of Australia 1994 (GDA94)
    (latitude and longitude)
  • Grid coordinates: (Universal Transverse Mercator, using the GRS80 ellipsoid)
    Map Grid of Australia 1994 (MGA94)
  • Reference Frame: ITRF92 (International Terrestrial Reference Frame 1992)
  • Epoch: 1994.0
  • Ellipsoid: GRS80
  • Semi-major axis (a): 6,378,137.0 metres
  • Inverse flattening (1/f): 298.257222101

Australian Fiducial Network

Geodetic GNSS receivers on the Australian mainland and Tasmania.

Australian National Network

Sites observed with GNSS as part of an Intergovernmental Committee on Surveying and Mapping (ICSM) cooperative project during 1993.