An interferometric radio telescope in outback Western Australia, the Murchison Widefield Array (MWA) is a fully operational precursor instrument to the future low-frequency Square Kilometre Array (SKA).
The MWA consists of 4,096 dipole antennas arranged in 256 regular grids (called ‘tiles’), which make up the front-end of the telescope and are spread over several kilometres within the Murchison Radio-astronomy Observatory (MRO). Data from the antennas is processed onsite via a correlator, before being transmitted to the Pawsey Supercomputing Centre for long-term storage. While the front-end works hard observing and processing data, the back-end of the telescope translates to an online platform, the MWA node of the All-Sky Virtual Observatory (MWA-ASVO). Through this platform, scientists are able to access calibrated MWA data – allowing them to make their spectacular discoveries.
A $1 million Australian Government grant enabled the MWA to undergo ‘brain surgery’, and its resulting processing capability is being hailed as a significant technological achievement and feat of software engineering.
The project might seem simple in concept: replace the insides of the MWA telescope’s computing racks. Of course, this task becomes more complicated when you consider that these computing racks have the crucial job of combining and processing every byte of data from thousands of antennas, and astronomers around the world rely on the quality and accuracy of its output.
These important computing racks are collectively called the correlator, best understood to be the ‘brain’ of radio telescopes like the MWA. The $1 million grant awarded in late 2020 allowed the purchase of a literal tonne of brand-new computing equipment, which would become the basis of the MWA’s new correlator, named ‘MWAX’ (with the ‘X’ in reference to the cross-correlation function it performs). MWAX was designed to not only replace its aging predecessor, but to improve the MWA’s data systems and support the telescope’s flexibility. The MWA first began scanning the southern skies in mid-2013, and the project has seen significant upgrades to its hardware since then – but the correlator remained untouched for the best part of a decade.
This original correlator contained many limitations, with only enough inputs to process half of the MWA’s 4,096 antennas at any one time (the design requirement in 2012). MWAX was designed with no such limitations – capable of performing 900 trillion floating-point calculations each second, with 24 Hewlett Packard Enterprise (HPE) servers each containing enterprise-grade A40 Graphics Processing Unit (GPU) cards. Together, these servers provide 1.4 million gigabytes of local storage for observations, before the data products are sent over fibre optic cable to Perth where they can be accessed online by astronomers around the world.
MWAX was custom-designed by an engineering team at Curtin University, the lead institute for the MWA telescope. The upgrade involved in-house software development, procurement, and benchmarking of state-of-the-art hardware systems, end-to-end testing, deployment, and installation on site, and finally, engineering and science commissioning. Remarkably, these efforts took only a year to complete, despite the challenges of an ongoing pandemic and global shortage of GPUs.
Curtin University Project Officer, Mia Walker, helped support MWAX from inception to completion, finding the process extremely rewarding.
MWAX was always the next step in the MWA’s evolution, which turned out to be more of a giant leap, really. I think it’s the best example of how we are achieving our goal to provide the highest quality data and service to the MWA Collaboration.
Since completion of commissioning in December 2021, the new correlator has received extremely positive feedback from MWA science teams and has exceeded expectations in key performance areas of operation (including visibility generation for over 100 different frequency and time resolutions, voltage capture and multicasting, and the integration of MWA’s new software libraries and archiving pipelines).
With a slew of new observing modes on offer, MWAX provides radio astronomers with greater opportunities to perform innovative science – which will likely add to the growing list of the MWA’s scientific achievements.
Among these, the MWA was instrumental in the detection of the largest known eruption in the universe since the Big Bang, the discoveries of ionospheric structures in the Earth’s atmosphere and an ultra-long period magnetar, the creation of a catalogue of 300,000 galaxies, and the first radio-colour panorama of the Universe.
See this link for press releases and popular media coverage related to MWA science.
The MWA’s capabilities also underpin its critical role as a ‘low-frequency precursor’ instrument for the $2 billion SKA project. Having commenced construction in 2021, the SKA will be the world’s largest radio astronomy observatory, designed to solve the deepest mysteries of the Universe, with telescopes in Western Australia and South Africa.
MWAX was funded via a National Collaborative Research Infrastructure Strategy (NCRIS) Contingency Reserve grant of $1M from the Department of Education Skills and Employment, provided to Curtin University and administered by AAL.
Australia’s national research infrastructure celebrated Indigenous knowledge and research during the 2021/22 period, with the release of a new interactive infographic.
As part of this infographic, AAL chose to highlight the work astronomers from the MWA have been doing with the Indigenous communities of the Mid West region in Western Australia, including Wajarri Yamaji people (the traditional owners of the SKA site), for over a decade.
MWA director, Prof. Steven Tingay from Curtin University, and colleagues from Yamaji Art in Geraldton, have brought together art, science, culture, and technology to curate world-wide art exhibitions and produce a feature length film. Please click here to read an article about making this film, written by Prof. Tingay and published in The Conversation.
These characteristics make the array invaluable for quickly mapping the sky and studying rare and faint events as they happen.
In addition to contributions from partner institutions, funding for MWA is provided by NCRIS via AAL. This funding provides support for staff salaries, infrastructure maintenance, utilities, and MRO site costs. AAL’s contribution of operations funding to the MWA ensures support is provided to the globally distributed network of researchers, engineers, planners, and managers dedicated, on behalf of the astronomical community, to the realisation of the SKA.