Murchison Widefield Array
The Murchison Widefield Array (MWA) delivers powerful new capabilities for radio astronomy and heliospheric science at frequencies from 80 to 300 MHz, optimized for extremely wide fields of view and unprecedented sensitivity at those frequencies. The MWA has specific scientific goals and is underway as an international project led and operated by Curtin University with strong collaboration from a number of international and Australian universities and research institutions.
The MWA’s primary science goals include detection of the weak neutral hydrogen from the Early Universe (the “Epoch of Reionisation”, when the first stars and galaxies illuminated the Universe, half a billion years after the Big Bang), and production of a 3 pi steradian (3/4 of the whole sky) map of the sky at low radio frequencies (the GLEAM catalogue). Its other science includes detection and characterisation of variable and transient radio sources, heliospheric and ionospheric science, and study of maser emission from our Galaxy.
The most common configuration of radio telescopes is the typical parabolic dish with a detector located at its focal point. Most of these telescopes have the ability to move the beam by either adjusting the orientation of the dish itself or even moving the detector to a different point above the dish. This however can cause problems as strong winds can perturb the dish and destroy the integrity of data. A major advantage of the MWA is the fact that it has no moving parts. Rather than an array of dishes, this instrument is a configuration of “tiles” each consisting of 16 dual-polarization dipole antennas.
Each tile consists of a large aluminium frame with a mesh ground plane. The dipoles sit on top of the ground plane by sliding through tubes built into the mesh, allowing a stable stronghold. Photographs of a dipole (left) and a tile under construction (right) can be seen below, showing the 16 dipoles on top of the ground plane.
The MWA consist of 8000 dual-polarization dipole antennas optimized for the 80-300 MHz frequency range arranged as 128 “tiles”, with 16 dipole antennas per tile in a 4×4 array.
The MWA offer radio astronomers the following unique features:
- Reliability, as the design contains no moving parts
- Multi-beaming capability with higher resolution than existing low frequency telescopes
- High angular resolution due to spacing of arrays
- Advances in communication technology allows for terabit/sec (1,000 gigabit/sec) transfer speeds
- Lessened Radio Frequency Interference
- Ability to correct for ionospheric distortion of signals using GPS calibration
For more information, visit the Murchison Widefield Array website.