It superseded the Chatham Islands Geodetic Datum 1971 (CIGD1971).
The origin of CIGD1979 is defined by the position of the mark Astro Station (geodetic code 5505, (43° 57' 23.60" S, 176° 34' 28.65" W). Orientation is provided by the adjusted azimuth determined by astronomical observations at four stations during 1968, 1970 and 1979. It is defined as 115° 58' 47.03" from Kahunene No 2 (geodetic code BARW) to B Kapangatakahu (geodetic code BARX).
The main parameters for CIGD1979 are summarised below:
Name: Chatham Islands Geodetic Datum 1979
Reference ellipsoid: International 1924
Reference frame: Astronomic datum
Reference Epoch: N/A
Deformation Model: N/A
In 1998 the NZGD2000 superseded CIGD1979 as the official geodetic datum in the Chatham Islands.