72 ears on one plate express
Radio telescopes are like ears listening to space. Usually, there's just one ear: it picks up a signal from a single tiny spot in the sky. That's slow. The Parkes telescope in Australia now has 72 ears working at once. They're cooled to liquid-helium temperatures so that the receivers' own noise doesn't drown out the faint whispers of distant galaxies.
The new system was tested on two targets: the Large Magellanic Cloud and the nearby galaxy NGC 6744. Both glow in the neutral hydrogen line — a radio wave 21 centimeters long emitted by hydrogen atoms when an electron flips its spin. Comparison with old maps showed that previous telescopes had missed vast but very diffuse gas clouds. Now they're visible.
But 72 beams bring a problem too: interference from terrestrial transmitters and background radiation can corrupt the signal. The astronomers tried new cleaning methods — three-dimensional data decomposition, similar to separating a complex cocktail into its original components. It turned out that this method preserves faint extended signals better than the old layer-by-layer approaches. This matters for future maps of hydrogen distribution in the Universe: they could let us trace how gas gathered into galaxies.
The new system at Parkes is not just an upgrade of one telescope. It's a test of technologies that will underpin future giant sky surveys. When 72 ears work simultaneously, the Universe tells its story faster and in more detail.
Original abstract
as written by the authors arXiv:2602.12677
Spectral-line results from a new cryogenic phased array feed (cryoPAF) on the Murriyang telescope at Parkes are presented. This array offers a significant improvement in field of view, aperture efficiency, bandwidth, chromaticity and survey speed compared with conventional horn-fed receivers. We demonstrate this with measurements of sky calibrators and observations of 21-cm neutral hydrogen (HI) in the LMC and the nearby galaxy NGC 6744. Within 0.3 deg of the optical axis, the ratio of system temperature to dish aperture efficiency is 25 K and the ratio with beam efficiency is 21 K (at 1.4 GHz). For the previously measured $$T_{sys} = 17$$ K, respective efficiency values 0.7 and 0.8 are derived. Our HI observational results are in good agreement with previous results, although detailed comparison with multibeam observations of the LMC suggests that the earlier observations may have missed an extended component of low-column-density gas ($$8\times 10^{18}$$ cm$$^{-2}$$). We use the cryoPAF zoom-band and wideband data to make a preliminary investigation of whether the large number of simultaneous beams (72) permits the use of novel data reduction methods to reduce the effects of foreground/background continuum contamination and RFI. We also investigate if these methods can better protect against signal loss for the detection of faint, extended cosmological signals such as HI intensity maps. Using robust higher-order singular value decomposition (SVD) techniques, we find encouraging results for the detection of both compact and extended sources, including challenging conditions with high RFI occupancy and significant sky continuum structure. Examples are shown that demonstrate that 3D SVD techniques offer a significant improvement in noise reduction and signal capture compared with more traditional layered 2D techniques.
The temperature of the new system's receivers is about 17 kelvins, or minus 256 degrees Celsius. That's colder than the surface of Pluto.
In Carl Sagan's novel Contact, radio telescopes listen to the sky for extraterrestrial signals. The new 72-beam system is a step toward listening in many directions at once and missing nothing.