From dirt to data, SKA-Low reaches first scientific milestone

BY SEBASTIAN NEUWEILER AND CASSANDRA CAVALLARO (SKAO)

The SKAO’s low-frequency telescope (SKA-Low) has achieved an exciting milestone, with the release of “first fringes”, just weeks after producing the first image from one station.

In August, the first image from observations using one complete SKA-Low station was produced, already generating excitement within the community when it was presented during the IAU General Assembly in South Africa. This came just 18 months after the start of construction activities on site, and just five months after the first antenna was installed at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory.

Only weeks later, the milestone of “first fringes” was achieved, with the first correlated signal from two separate antenna stations being obtained. This data shows the SKA-Low is working as an interferometer – an instrument that uses many individual antennas, spread over a large distance, to form a large virtual telescope.

SKAO Director-General Prof. Philip Diamond said this marked “the day the SKA Observatory as a scientific facility was born”.

SKA-Low’s antennas do not move, instead using a technique called beamforming to digitally point at different parts of the sky. The data is then combined and correlated to make sense of the radio signals which arrive at each antenna at marginally different times.

SKA-Low Lead Commissioning Scientist Dr George Heald said finding a strong correlated signal between the first two SKA-Low stations means that the instrument works as expected.

“Now we can scale up the scientific power of SKA-Low as we add more and more stations over the next few years, ultimately enabling us to search for the unknown,” he said.

“This is an incredible milestone. Many astronomers, including myself, are so excited for what comes next as this telescope continues to scale.”

These scientific works use data obtained from Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory. We acknowledge the Wajarri Yamaji as the Traditional Owners and Native Title Holders of the Observatory site.

Taken over 24 hours, the first image from a whole SKA-Low station shows the Milky Way rising and passing overhead, as well as the galaxies Centaurus A and M87. The image demonstrates the high sensitivity of a single station and provides a glimpse into the future power of the telescope, with the resolution expected to be 100,000 times higher once all 512 SKA-Low stations are operational.

First fringes: these graphics (above and below) show the phase structure of the correlated signal between two SKA-Low stations of 256 antennas each.