First ASKAP antenna on-site in Western Australia.
Wallaby in the Wild.

© Wallaby in the Wild.
(Photo credit: Tobias Westmeier)

Welcome

WALLABY is the "ASKAP HI All-Sky Survey", a precursor for future, much deeper SKA Phase 1 & Phase 2 neutral hydrogen (HI) surveys. With an integration time of ~1 year (or 8 hours per pointing) WALLABY will cover two-thirds of the sky to redshifts of z = 0.25. Using our best source-finding algorithms (PASA Special Issue 2012 - ed. Koribalski), we estimate that in the survey volume around 600 000 galaxies are individually detectable in the 21-cm line of neutral atomic hydrogen (Johnston et al. 2008; Koribalski & Staveley-Smith 2009; Duffy et al. 2012). We will measure the HI properties of each galaxy and derive its distance, HI mass, total mass and dark matter content. Most galaxies will also be detected in the 20-cm radio continuum, allowing us to derive their star-formation rates. The 30 arcsec angular resolution of WALLABY will allow us to identify likely optical and/or infrared galaxy counterparts. - For a brief overview of WALLABY see Koribalski (2012b).

Oct 2014 NEWS * WALLABY Newsletter No 6

Sep 2014 NEWS * ASKAP 9-beam HI mosaic of a nearby galaxy group

PhD top-up scholarship

August 2014 NEWS * ASKAP maps HI in Scultpor pair NGC 253 and NGC247

May 2014 NEWS * ASKAP detects NGC 253's extended HI disk

Apr 2014 * First ASKAP 15 baseline observations

Feb 2014 NEWS * WALLABY Newsletter No 5

Feb 2014 NEWS: First 9-beam image with six ASKAP PAFs

In February 2014 the first 9-beam image was made using the full 304 MHz bandwidth and combining the data from two BETA sub-arrays, each consisting of three PAF-equipped ASKAP antennas. The three bright extragalactic sources in the field are PKS 1610-771, PKS 1549-790 and PKS 1547-795. The associated press release is here.

First 
   9-beam image from six PAF-equipped ASKAP antennas (BETA-1 + BETA-2 arrays; 
   six baselines).


Oct & Nov 2013: First HI detection with three ASKAP PAFs

On Oct 16, 2013, the first HI detection was made with three ASKAP PAFs. Auto-correlation spectra for a single PAF port were obtained using the hardware correlator; our target was the standard Galactic S9 region located at RA,DEC(J2000) = 17:52:05.4, -34:25:15.4, Bruens et al. 2005).

In Nov 2013 the first HI absorption detection was achieved towards the gravitational lens PKS 1830-211 at z = 0.89 using the cross-correlation data from three BETA antennas. - Further ASKAP HI observations will be carried out soon and will hopefully result in the first ASKAP HI cube.

Apr 2013: First 3-beam image with three ASKAP PAFs

In August 2012 first fringes between three PAF-equipped ASKAP antennas as well as zero closure phase measurements were obtained towards the radio galaxy Virgo A (M87). In April 2013 the first high-quality multibeam image was obtained with the BETA1 system (928 MHz, 16 x 1 MHz bandwidth, 1 pol, 12h integration time, all with the interim software correlator). The first 9-beam image was recently obtained using three PAFs and the new hardware correlator. Another three Mk1 PAFs are currently being installed on site. Engineering and science commissioning with six PAF-equipped ASKAP antennas - known as BETA - is expected to happen towards the end of 2013.

First 3 PAFs on ASKAP.


2012 PASA Special Issue (Vol 29, Issue 3)

The 2012 PASA Special Issue on Source Finding and Visualisation is now complete and all papers are online. I like to thank all authors for their contributions.

2012 SKA Site Decision

On May 25, 2012, the SKA Members met and adopted a dual-site implementation for SKA Phase 1 and SKA Phase 2. The SKA Phase 1 implementation will use existing (or currently being built) infrastructure at both sites, including the precursor telescopes, ASKAP in Australia and MeerKAT in South Africa. After demonstrating the power of PAFs on ASKAP (and WSRT), it is planned - as part of SKA Phase 1 - to add an array of 60 PAF-equipped dishes to ASKAP.

2011 Simulations Fest

General Information

ASKAP is the "Australian SKA Pathfinder". See ASKAP Live ! and the ASKAP Webcams for up-to-date information. As ASKAP design and software are progressing rapidly, we have assembled international science teams who will carry out survey design studies, liase with the software team, explore the sky via cosmological simulations and write many excellent papers.

WALLABY - led by B. Koribalski and L. Staveley-Smith - is the top-ranked spectral line survey. It will observe the sky up to declinations of +30 degr over the frequency range of 1130 - 1430 MHz, ie velocity range of -2,000 to +77,000 km/s at approx. 4 km/s resolution. Assuming a Tsys of 50 K we will integrate for 8h (or more) per field. See our survey proposal for details.

ASKAP will consist of 36 x 12-m antennas (4072 sq m) with phased array feeds providing a field-of-view of 5.5 deg x 5.5 deg (= 30 sq deg) operating in the range 0.7 - 1.8 GHz, i.e. ideal for large HI line and 20-cm continuum surveys. The inner 30 antennas (3400 sq m) of ASKAP are optimally arranged in a 2-km configuration, delivering an angular resolution of 30". A further six antennas will be placed at larger distances (baselines up to 6-km), giving an angular resolution of ~10".

The first ASKAP antenna arrived on site in December 2009. The picture at the top shows the fully assembled antenna on its pad in Western Australia (WA). Phased array feed (PAF) design is on-going with testing under way on the Parkes 12-m test antenna. Recent Tsys results of the PAF MkII system are very encouraging (close to Tsys = 50 K across the band). --- Construction of all 36 ASKAP antennas is now complete. PAFs are currently installed on all six BETA antennas (1, 3, 6, 8, 9 and 15). Engineering commissioning is continuing and will soon be including first spectral line observations.

ASKAP + WSRT-APERTIF

A true all-sky survey cannot be achieved with a single ground-based telescope alone. While ASKAP can "see" more than 2/3 of the sky, it cannot see the whole sky. WSRT equipped with focal plane arrays (APERTIF) would provide the ideal complement to ASKAP. An APERTIF Expression-of-Interest for a WSRT Northern Sky HI Survey (WNSHS; DEC > +27 degr) was submitted on Sep 22, 2010 (led by Gyula Jozsa). A full proposal is now being prepared.

Computing

Funding of the Pawsey Centre and the NBN link between Geraldton and Perth may in future (tbd) provide the computing power needed to process the full spectral line visibilities from all 36 ASKAP antennas with baselines up to 6-km, in contrast to the previous limitation to the inner 30 antennas (baselines < 2 km). This has many implications:

Questions to address:


IDEAS !

Idea: develop GalaxyZoo for Wallaby :)

Page design and maintenance: B. Koribalski
Last updated on the 1st of June, 2014