The Rapid ASKAP Continuum Survey as a virtual map

ASKAP Science

ASKAP is an SKA-precursor telescope that observes radio waves of a mid-band frequency. Other SKA telescopes at the MRO site are low-band frequency telescopes.

While the SKA mid-band projects are now based in South Africa, ASKAP showed just how valuable mid-band studies are, how much data can be acquired, and helped engineers and astronomers refine the technologies for SKA. Now that ASKAP is part of the Australian Telescope National Facility, it has a lot to offer researchers from all around the world. 

ASKAP is designed to peer deep into our Universe in record time. This speed, which allows it to survey large parts of the sky quicker than any before, is due to its wide field of view. The telescope uses new technology developed by CSIRO - phased array feeds (PAFs) that sit at the focus of each of its antennas to generate this unique widefield view. 

Because of this, we regularly see many new cosmic objects being discovered by the researchers using ASKAP.

More information can be found on CSIRO’s ASKAP page
 

What is ASKAP looking for?

No, not aliens. In the early pilot stages, ASKAP is involved in highly explorative research. Researchers design surveys that use ASKAP’s unique capabilities to map the structure and evolution of the Universe by observing galaxies and the hydrogen gas that they contain. The RACS project, imaged above, found 1 million new galaxies.

 

Survey Science Projects

During ASKAP’s first five years of operation at least 75% of its time is being used for large survey science projects, each needing more than 1,500 hours to complete and all designed to test the telescope’s unique capabilities. The projects were selected in 2009 by an international panel, with the decision based on scientific merit and operational feasibility. 

In August 2021, these projects started their second pilot surveys with all 36 ASKAP dishes and now involved 739 astronomers from 208 institutions around the world. Many papers resulting from the work can be found on the Publications page. Data from their projects is accessible via the CSIRO ASKAP Science Data Archive (CASDA).

Each survey science project has a different research objective that is summarised below in alphabetical order by team name. You can also visit the ASKAP Survey Science Confluence page.

 

CRAFT (The Commensal Real-time ASKAP Fast Transients survey)
Principal Investigators: Keith Bannister (CSIRO) and Ryan Shannon (Swinburne University)
CRAFT is a purely commensal survey for transient sources with timescales shorter than 5 seconds. Short-timescale transients are associated with the most energetic and brightest single events in the Universe. They provide Nature’s ultimate laboratory; their emission is generated by matter under extreme conditions whose properties probe physical regimes far transcending the range achievable in terrestrial experiments. Fast timescale transients open new vistas on the physics of high brightness temperature objects, extreme states of matter and the physics of strong gravitational fields. In addition, the detection of extragalactic transients affords us an entirely new and sensitive probe on the huge reservoir of baryons in the intergalactic medium. 

DINGO (Deep Investigations of Neutral Gas Origins)
Principal Investigator: Martin Meyer (ICRAR/University of Western Australia)
DINGO will study the evolution of neutral hydrogen (HI) from the current epoch to redshift about 0.5, providing a legacy dataset spanning cosmologically representative volumes. Measurements will be made of key cosmological distributions, including ?HI, the HI mass function and the halo occupation distribution function. ASKAP data will be combined with optical data to enable a thorough study of the co-evolution of the stellar, baryonic and dark matter content of galaxies. 

EMU (Evolutionary Map of the Universe)
Principal Investigator: Andrew Hopkins (Macquarie University)
EMU is a deep (10 μJy/beam rms) radio continuum survey of 75% of the entire sky. EMU will probe typical star forming galaxies to redshift 1, powerful starbursts to even greater redshifts, Active Galactic Nuclei to the edge of the Universe, as well as undoubtedly discovering new classes of rare objects. The key science goals for EMU are to trace the evolution of star forming galaxies and massive black holes throughout the history of the Universe and to explore large-scale structure. EMU will create the most sensitive wide-field atlas yet made, and provide a long-lasting legacy survey. 

FLASH (The First Large Absorption Survey in HI)
Principal Investigators: Elaine Sadler (University of Sydney) and James Allison (Oxford)
FLASH is a blind HI absorption-line survey that uses background radio continuum sources to identify and characterise foreground neutral hydrogen. FLASH science outcomes are focused on both the neutral gas content of galaxies and the cosmic HI mass density in the redshift range 0.5 < z < 1.0 where the HI emission line is too weak to be detectable in individual galaxies. The observations will increase the total number of absorption line systems by an estimated two orders of magnitude, representing a significant data set to study gas assembly and galaxy formation during a time in the history of the Universe that is largely unstudied thus far. 

GASKAP (The Galactic ASKAP Spectral Line Survey)
Principal Investigators: John Dickey (University of Tasmania) and Naomi McClure-Griffiths (ANU)
GASKAP is a high spectral resolution survey of the HI and OH lines in the Milky Way and Magellanic Systems. Compared with existing data, GASKAP will achieve about an order of magnitude improvement in both brightness sensitivity and in angular resolution. GASKAP will detect and map OH masers from evolved stars and star formation regions, diffuse emission from molecular and atomic clouds, HI absorption toward background continuum sources and the structures in the gas that trace the effects of stellar winds and supernova explosions. The Magellanic Clouds will show all these processes as they appear in two other, very different environments. GASKAP will provide stunning images of the interstellar medium that will be indispensible for astronomers working at other wavelengths.

POSSUM (Polarization Sky Survey of the Universe's Magnetism)
Principal Investigators: Bryan Gaensler (Dunlap Institute for Astronomy and Astrophysics, University of Toronto), Naomi McClure-Griffiths (ANU) and George Heald (CSIRO)
Understanding the Universe is impossible without understanding magnetic fields. Magnetic fields are key to the non-thermal Universe, yet it is unclear how large-scale magnetic fields are generated and maintained. POSSUM will use radio source polarization, in particular the technique of rotation measure (RM) synthesis, to perform a wide-field survey that will yield a grid of RMs over a substantial fraction of the sky. The science outcomes of POSSUM will revolutionise our understanding of the ordered components of the Milky Way’s magnetic field, test dynamo and other models of magnetic field generation in galaxies and clusters, and carry out a comprehensive census of magnetic fields as a function of redshift in galaxies, active galactic nuclei, galaxy clusters and the intergalactic medium. 

VAST (An ASKAP Survey for Variables and Slow Transients)
Principal Investigators: Tara Murphy (University of Sydney) and David Kaplan (Wisconsin)
VAST gives unprecedented opportunities to investigate the sky at radio wavelengths for transients with a timescale as short as five seconds. ASKAP’s wide-field survey capabilities will enable the discovery and investigation of variable and transient phenomena from the local to the cosmological including flare stars, intermittent pulsars, X-ray binaries, magnetars, extreme scattering events, intra-day variables, radio supernovae and the orphan afterglows of gamma-ray bursts. VAST will probe unexplored regions of phase space where new classes of transient sources may be detected. 

WALLABY (Widefield ASKAP L-Band Legacy All-Sky Blind Survey)
Principal Investigator: Lister Staveley-Smith (ICRAR/University of Western Australia)
WALLABY is an extragalactic neutral hydrogen survey over 75% of the entire sky and will detect up to 500,000 galaxies to a redshift of 0.26. The fundamental aims of WALLABY are to examine the HI properties and large-scale distribution of these galaxies in order to study galaxy formation and the missing satellite problem in the Local Group, evolution and star formation of galaxies, the role of mergers and galaxy interactions, the HI mass function and its variation with galaxy density, the physical processes governing the distribution and evolution of cool gas at low redshift, cosmological parameters relating to gas-rich galaxies and the nature of the cosmic web. WALLABY will provide the largest, most homogeneous HI sample of galaxies yet made, and will be an important pathfinder for key SKA science.

 

A section of the atomic hydrogen gas in the Small Magellanic Cloud as imaged with ASKAP. Credit: ANU and CSIRO

 

What has ASKAP and the survey science projects found?

Early science projects, using only 16 of the 36 dishes, produced incredible new imagery of our universe. GASKAP produced an image of the Small Magellanic Cloud in 2017 (a small segment seen above), showing us the tangled web of gas that makes up our neighbouring galaxy. It reveals the galaxy’s vibrant history, including streams of gas reeled in by the gravitational pull of the Milky Way and billowing voids generated by massive stars that exploded millions of years ago. 

What’s amazing about this image is that it was made in one shot with the ‘wide-angle’ camera of ASKAP. To do this with traditional technology you would have had to point the telescope in 1,344 different places across the face of the Galaxy and run five observing sessions over 15 months. By contrast, ASKAP took just three nights. Data from CSIRO’s Parkes radio-telescope was added to pick up the faint diffuse emission which is essential for understanding the Galaxy as a whole.
Since then, and with 20 more antennas in use, ASKAP has recorded many more astounding galaxies and phenomena – many of them a mystery. 

Read more about:

Visit the ASKAP news page, and our Publications page for more up to date discoveries.

 

Where is ASKAP data kept?

CASDA provides all ASKAP data (image cubes, basic catalogues, and averaged visibilities) to the public free of charge. Archive products are available as soon as they have gone through a quality control process. The project teams will be providing value-added data products (e.g. large-scale catalogues, rotation measure maps) based on the released data products.
•    Visit the CASDA page
•    Search the archive using a web interface
•    Read the user’s guide to the archive 
 

ASKAP is an SKA-precursor telescope situated at the MRO in Western Australia.
We acknowledge the Wajarri Yamatji as the traditional owners of the Murchison Radio-astronomy Observatory site.

 

 

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