Murriyang, our Parkes radio telescope

You can find an overview about Murriyang, the 64m Parkes radio telescope, at the main CSIRO Parkes page.

This page explains some of the technology and techniques used when observing pulsars such as in PULSE@Parkes sessions.

How does Murriyang work?

The antenna

Parkes has a parabolic dish antenna, 64 m in diameter with a collecting area of 3,216 m². The dish is made up of aluminium panels supported by a lattice-work of supporting struts (b and c in the photo above). To incoming radio waves from space, the dish surface acts in the same manner as a smooth mirror. The waves are reflected and focused into a receiver in the base of the telescope’s focus cabin (a in photo above). The dish has a mass of 300 tonnes and distorts under its own weight as it points to different parts of the sky. Due to clever engineering design, however, this distortion is accounted for so that the radio waves are always reflected to the focus cabin.

Why is the dish so big?

The size of a dish determines the amount of incoming radiation that can be collected. The larger the collecting area, the fainter the source that can be detected. The signals from deep space astronomical sources are incredibly faint so astronomers are keen to use as much collecting area as possible. Parkes is a 64 m antenna, the second-largest single dish in the southern hemisphere.

For a single-dish radio telescope the size of the dish also determines the field-of-view of the telescope. When a single receiver is used the Parkes telescope has a beamwidth of about 15 arc minutes, half the size of the Moon in the sky.

The receivers

The weak radio signals are channeled by the feedhorn into a receiver located in the focus cabin located at the top of the telescope. Radio receivers amplifies the incoming signal about a million times. Parkes has a suite of receivers that are optimised for different frequency ranges and applications. The receivers are cryogenically cooled, typically with helium gas refrigerators that cool them to about 10 Kelvin (-260° C) to minimise the thermal noise in the electronics that would otherwise swamp the incoming signal.

The current receiver used for most pulsar observations is the new Ultra Wide-bandwidth Low (UWL) receiver system. It provides continuous frequency coverage from 704 – 4032 MHz. It amplifies then digitises the signals then packets them using field programmable gate arrays (FPGAs).

Another receiver is due for installation in early 2023. This is the CryoPAF (Cryogenically-cooled Phased Array Feed). Like the UWL t was developed by Space and Astronomy engineers at our lab in Marsfield, Sydney. The CryoPAF builds on the technology developed for the Phased Array used on ASKAP and can be thought of as a very sensitive wide-field “radio camera”.

Processing the signals

Once the data has been packetised in the FPGAs, it is sent to the GPU correlator (or backend) called Medusa. At this point, Medusa carries out the astronomy processing including pulsar fold-mode (timing) observations, search mode and single-pulse observations as well as continuum/spectral line observations.

Observing

The Parkes radio telescope, like all those operated by Space and Astronomy, can be operated remotely from anywhere with reliable internet. The astronomer is responsible for their own observations though in fact almost all observing projects are collaborations involving teams of people from across Australia and around the World.

The telescope is controlled via a graphic interface, Dhagu?, (which is the Wiradjuri word meaning where to?) running in a browser. Using Dhagu? the observer controls the telescope and receivers, monitors the status of all the telescope systems, schedules observations, and views the data though a backend, Medusa.

Further feedback is provided via another interface, FROG that is also viewed in a browser. FROG shows a wealth of information including a webcam image of the telescope, wind strength and direction, telescope status, time information and a plot of the telescope on the sky plus more.

MEDUSA a GPU-based signal processing unit that was specifically designed to support the UWL receiver. It is capable of processing each of the 26, 128-MHz sub-bands of the whole UWL bandpass independently in any of the observing modes including search, fold and continuum modes. During a PULSE@Parkes session we mostly use the fold mode but can display other modes to highlight different phenomena and features.

Research

The Parkes radio telescope is one of the most productive and cited radio telescopes globally.

• More than half of all the currently known about 3,000 pulsars were discovered with Parkes.
• The first Fast Radio Burst (FRB) was discovered in 2007 when astronomers re-examined Parkes pulsar observations made in 2001.
• Parkes is currently one of the telescopes used by the Breakthrough Listen project searching for Extraterrestrial Intelligence.

Telescope Details

Telescope details
Diameter of antenna	64 m
Collecting area of antenna	3,216 m2
Height to top of focus cabin	58 m
Focal length	27.4 m
Mass of antenna	300 tonnes
Mass above control tower	1,000 tonnes
Maximum tilt	60°
Time to maximum tilt	5 minutes
Time for 360° rotation	15 minutes
Surface accuracy	1-2 mm difference from best-fit parabola
Pointing accuracy	11 arcseconds rms in wind
Maximum operating wind speed	35 km per hour
Motors	4 × 15 hp 480 volt DC 40,000:1 gear ratios
Key Receivers:
Ultra Wide-bandwidth Low (UWL)	704 – 4032 MHz bandwidth
CryoPAF (due for installation early 2023)	700 MHz to 1.9 GHz bandwidth

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More Information?

• CSIRO page for the Public about Parkes
• Parkes Observatory Visitors Centre
• Parkes and the Apollo 11 Moon Landing
• 5 things you didn’t know about the Parkes radio telescope
• Detailed information for Parkes observers
• Current Parkes schedule

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Murriyang, the Parkes radio telescope is part of the Australia Telescope National Facility which is funded by the Australian Government for operation as a National Facility managed by CSIRO. We acknowledge the Wiradjuri people as the traditional owners of the Observatory site.