Spatial -

NOAA Datums Videos 2014

Differential correction with NA2011 and the newest epoch of NAD83

See our and Datums Basics and GPS Tutorials for the long-awaited results of months of rigorous testing and peer review

Trimble Positions software has replaced Trimble GPS Analyst in ArcGIS 10.1

ALASKA GPS and GIS users - check out Joel Cusick's Datum and Projections presentation Feb 2013

ArcGIS 10.1 - New and Cool improvements see Presentation from Melita Kennedy, ESRI : Projections and Datums Dec 2012

Home Datums Basics WGS84 - World Geodetic System 1984
WGS84 - World Geodetic System 1984 PDF Print E-mail

World Geodetic System 1984 (WGS84) is an absolute positioning system with no ground controls but exclusively based on satellite orbits with no ground controls.  It was created by the Department of Defense (DOD) for the satellite systems.  As first released in 1987, WGS84 was based on Doppler measurements.  In 1994, WGS84 incorporated GPS and also became a dynamic reference frame through its association with ITRF. 

The below shows the 4 updates of the WGS84 reference system

release           realization/epoch                 identical to

1987               “Original” WGS1984              NAD83(1986)

1994               WGS84(G730)                      ITRF91 or 92 - varies in literature

1997               WGS84(G873)                      ITRF94 or 96 - varies in literature

2002               WGS84(G1150)                    ITRF00

2012               WGS(1674)                          ITRF08

* G denotes GPS and week number starting from Jan 2, 1994.

On 8 February 2012, GPS week 1674, NGA implemented the latest realization of the World Geodetic System 1984 (WGS 84), bringing WGS 84 into alignment with the International Terrestrial Reference Frame of 2008 (ITRF08)." The most current realization of WGS84 is WGS84(G1674).

External links to more on evolution of datums : NGS/R. Snay and T. Soler, Electronic Data Solutions