Murchison Widefield Array

The Murchison Widefield Array (MWA) is a joint project between an international consortia of organisations to construct and operate a low-frequency radio array. Operating in the frequency range 70–300 MHz, the main scientific goals of the MWA are to detect neutral atomic Hydrogen emission from the cosmological Epoch of Reionization (EoR), to study the sun, the heliosphere, the Earth's ionosphere, and radio transient phenomena, as well as map the extragalactic radio sky. The MWA was to be situated at Mileura Station where initial testing had been conducted then moved southwest to Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO), 800 kilometres north of Perth. This location offers a quiet radio environment and stable climate for observations. The MRO is also the site of CSIRO's Australian Square Kilometre Array Pathfinder (ASKAP) and one of two selected sites for the Square Kilometre Array (SKA). In addition to the geographic link, the MWA is one of four official SKA precursor telescopes – instruments that provide instrumental, scientific and operational information to help guide SKA developments. The MWA was initially conceived as a 512-tile instrument (512T) to be built in stages. The first stage was a 32-tile prototype (MWA-32T) which was constructed and operated with increasing capability over the period 2007–2011, testing telescope hardware and making preliminary science observations, including initial observations of EoR fields. The first phase of the telescope, the so-called 'Phase I MWA' achieved full practical completion in late 2012 and completed commissioning on 20 June 2013, before moving into full operations. The Phase I MWA was the first so-called large-N array, fully cross-correlating signals from 128 phased tiles, each of which consist of 16 crossed dipoles arranged in a 4x4 square. As part of a planned future roll out infrastructure on-site at the MRO was installed during Phase I to allow an eventual build-out to 256 tiles. The total cost of the first phase of the project was A$51 million. The Phase I array was largely driven by the second MWA director, Steven Tingay. In 2017 the telescope received the planned substantial upgrade, doubling both the number of antennas and the resolution of the instrument; increasing the sensitivity by a factor of approximately 10. This upgraded instrument is known as the 'Phase II MWA'. Phase II was practically completed in October 2017 and officially launched on 23 April 2018. Installation of the additional antennas and commissioning of the array was led by the third MWA director, Randall Wayth and operation of the Phase II instruments have been led by the current director, Melanie Johnston-Hollitt.