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The HI 21cm absorption line is masked by bright foregrounds and systematic distortions that arise due to the chromaticity of the antenna used to make the observation coupling to the spectral inhomogeneity of these foregrounds. We…

Instrumentation and Methods for Astrophysics · Physics 2021-11-12 Dominic Anstey , Eloy de Lera Acedo , Will Handley

The Boolardy Engineering Test Array is a 6 x 12 m dish interferometer and the prototype of the Australian Square Kilometre Array Pathfinder (ASKAP), equipped with the first generation of ASKAP's phased array feed (PAF) receivers. These…

We describe algorithms that detect 21cm line HI self-absorption (HISA) in large data sets and extract it for analysis. Our search method identifies HISA as spatially and spectrally confined dark HI features that appear as negative residuals…

Generation of science-ready data from processed data products is one of the major challenges in next-generation radio continuum surveys with the Square Kilometre Array (SKA) and its precursors, due to the expected data volume and the need…

Instrumentation and Methods for Astrophysics · Physics 2024-02-26 S. Riggi , G. Umana , C. Trigilio , C. Bordiu , F. Bufano , A. Ingallinera , F. Cavallaro , Y. Gordon , R. P. Norris , G. Gürkan , P. Leto , C. Buemi , S. Loru , A. M. Hopkins , M. D. Filipović , T. Cecconello

The present operation of the ground-based network of gravitational-wave laser interferometers in "enhanced" configuration brings the search for gravitational waves into a regime where detection is highly plausible. The development of…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-13 John Veitch , Alberto Vecchio

A new era in radioastronomy will begin with the upcoming large-scale surveys planned at the Australian Square Kilometre Array Pathfinder (ASKAP). ASKAP started its Early Science program in October 2017 and several target fields were…

Instrumentation and Methods for Astrophysics · Physics 2019-09-16 S. Riggi , F. Vitello , U. Becciani , C. Buemi , F. Bufano , A. Calanducci , F. Cavallaro , A. Costa , A. Ingallinera , P. Leto , S. Loru , R. P. Norris , F. Schillirò , E. Sciacca , C. Trigilio , G. Umana

We present a Bayesian angular power spectrum and signal map inference engine which can be adapted to interferometric observations of anisotropies inthe cosmic microwave background, 21 cm emission line mapping of galactic brightness…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 P. M. Sutter , Benjamin D. Wandelt , Siddharth Malu

The process of determining the number and characteristics of sources in astronomical images is so fundamental to a large range of astronomical problems that it is perhaps surprising that no standard procedure has ever been defined that has…

Instrumentation and Methods for Astrophysics · Physics 2015-06-03 Minh Huynh , Andrew Hopkins , Ray Norris , Paul Hancock , Tara Murphy , Russell Jurek , Matthew Whiting

We present a study, done with the Australian LBA, of HI absorption for two compact radio galaxies (PKS 1549-79 and PKS 1814-63). In both the radio galaxies, the HI appears to give us information about the environment in which the radio…

Astrophysics · Physics 2007-05-23 R. Morganti , T. A. Oosterloo , C. N. Tadhunter , K. A. Wills , A. Tzioumis , J. Reynolds

This paper presents a new Bayesian spectral unmixing algorithm to analyse remote scenes sensed via sparse multispectral Lidar measurements. To a first approximation, in the presence of a target, each Lidar waveform consists of a main peak,…

The Australian Square Kilometre Array Pathfinder (ASKAP) will give us an unprecedented opportunity to investigate the transient sky at radio wavelengths. In this paper we present VAST, an ASKAP survey for Variables and Slow Transients. VAST…

Using the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP BETA), we have carried out the first $z = 0 - 1$ survey for HI and OH absorption towards the gravitationally lensed quasars PKSB1830$-$211…

I describe an approach to fitting and comparison of radio spectra based on Bayesian analysis and realised using a new implementation of the nested sampling algorithm. Such an approach improves on the commonly used maximum-likelihood fitting…

Instrumentation and Methods for Astrophysics · Physics 2009-12-14 Bojan Nikolic

We present the largest Galactic neutral hydrogen HI absorption survey to date, utilizing the Australian SKA Pathfinder Telescope at an unprecedented spatial resolution of 30''. This survey, GASKAP-HI, unbiasedly targets 2,714 continuum…

This paper presents a general stochastic model developed for a class of cooperative wireless relay networks, in which imperfect knowledge of the channel state information at the destination node is assumed. The framework incorporates…

Applications · Statistics 2015-05-19 Gareth W. Peters , Ido Nevat , Scott A. Sisson , Yanan Fan , Jinhong Yuan

Over the past 10 years Bayesian methods have rapidly grown more popular as several computationally intensive statistical algorithms have become feasible with increased computer power. In this paper, we begin with a general description of…

Astrophysics · Physics 2016-02-19 David A. van Dyk , Alanna Connors , Vinay L. Kashyap , Aneta Siemiginowska

The Australian SKA Pathfinder (ASKAP) is being used to undertake a campaign to rapidly survey the sky in three frequency bands across its operational spectral range. The first pass of the Rapid ASKAP Continuum Survey (RACS) at 887.5 MHz in…

We present early science results from the First Large Absorption Survey in HI (FLASH), a spectroscopically blind survey for 21-cm absorption lines in cold hydrogen HI gas at cosmological distances using the Australian Square Kilometre Array…

The Australian SKA Pathfinder (ASKAP) is a next generation radio telescope currently under construction in Western Australia. The fast survey speed and wide field of view make it an ideal instrument for blind transients searches. The ASKAP…

Instrumentation and Methods for Astrophysics · Physics 2012-01-17 Jay Banyer , Tara Murphy , the VAST Collaboration