WA/NT border north of 26° south and the WA/SA border south of the 26th parallel. 1927–31 In 1927 the Northern Territory was split into two territories, North Australia (NA) and Central Australia (CA). (1 March 1927 – MAP). From 1927 to 1931 129° east was once again the WA/NA border and WA/CA border, both north of 26° south and the WA/SA border south of the 26th parallel. 1931–present In 1931 North Australia and Central Australia were reunited as the Northern Territory. (12 June 1931 – MAP). From 1931 to the present 129° east has been the WA/NT border north of 26° south and the WA/SA border south of the 26th parallel. Marking the WA border on the ground History of fixing the border Fixing the position of the border of Western Australia on the ground has a rich history. In March 1920 the Western Australian Government Astronomer, Harold Curlewis gave a talk at the WA Museum about the history of the determination of longitude, in relation to using what was at that time a new technology, by using wireless time signals to determine the position of the border between South Australia and Western Australia, as close to the 129th east meridian as possible. WA/SA border marking history Preliminary work on the border determinations began in November 1920 when the Government Astronomer for South Australia, Dodwell and the Western Australian Government Astronomer, Harold Curlewis met at Deakin, Western Australia on the East-West Trans-Australian Railway. The other members of the party were Messrs. Clive Melville Hambidge and J. Crabb, of the Survey Department; Warrant Officer V. D. Bowen, in charge of wireless apparatus lent by the Defence Department; and Mr. C. A. Maddern, of the Adelaide Observatory, all from Adelaide. Concrete piers for the astronomical observing instruments were erected in readiness for the final determinations that were to be held in 1921. Observations were made for the purpose of testing under field conditions the instruments and methods to be used in 1921. This expedition, to determine 129° east on the ground, created worldwide scientific interest and involved the cooperation of the Astronomer Royal and the Royal Observatory, Greenwich, with wireless time signals sent by the French wireless Service, that were transmitted from the Lyon Observatory at Saint-Genis-Laval, near Lyon, France, between 17 and 24 November 1920. Wireless time signals were also sent from the Adelaide Observatory, transmitted by the Adelaide Radio Station,