Scientists in Australia claim to have successfully tested the first antenna on the world’s largest, most sensitive international radio telescope — still under construction.

The first antenna to be assembled as part of the Australia Square Kilometre Array Pathfinder (ASKAP) telescope which is expected to be completed by 2013, has received its first radio signals.

The first of 36 identical 12-metre dishes that will make up the ASKAP telescope, the antenna was assembled over the Australian summer at the Murchison Radio-astronomy Observatory in the Mid West region of Western Australia.

The first radio signals were received from a satellite and were part of a project to measure the shape of the antenna’s surface using holography.

This involves combining a satellite test signal reflected from the antenna’s surface with the same signal received by a small ‘reference’ dish, producing an image that shows if the antenna’s surface deviates from the ‘perfect’ shape, say the scientists.

“It’s a great moment — the first time a telescope receives light or radio waves — is always very satisfying and exciting. It means the project is firmly on track. The test results show that the antenna is working beautifully, beyond specifications,” CSIRO’s ASKAP Project Director Dr. David DeBoer said.

The first ASKAP antenna — 12m in diameter and 18m high — has an extremely innovative design, having three moving axes (altitude, azimuth and polarisation) whereby the entire dish rotates in unison with the sky.

This unusual feature enables very sensitive images of the sky to be observed with the antenna’s phased array receiver or “radio camera”, making the processing of the signals much simpler than with conventional designs.

“We have arrived at this point thanks to tremendous efforts by the construction teams which erected the antenna through the heat of summer, and the team supporting the holographic testing,” Dr. DeBoer said.

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