Orientation of the Australian Geodetic Datum

The Australian Geodetic Datum is defined in relation to an earth centred system of co-ordinates. The technique for mapping the geoid on the latter system is outlined, using a composite solution from surface gravity data for the closer areas and a combination of satellite observations and gravimetry for the distant zones. Such a solution is used to relate the Australian Geodetic Datum to the centre of the earth by the continent wide comparison of astrogeodetic data and the gravimetric solution. This provides a set of corrections for the co-ordinates of the origin which enables all points on the datum, whose relative positions are known to first order geodetic accuracy, to be related to the geocentre with an uncertainty approximately an order smaller than at present.