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1. A Digital-Receiver for the Murchison Widefield Array

Author

Prabu, Thiagaraj, Srivani, K. S., Roshi, D. Anish, Kamini, P. A., Madhavi, S., Emrich, David, Crosse, Brian, Williams, Andrew J., Waterson, Mark, Deshpande, Avinash A., Shankar, N. Udaya, Subrahmanyan, Ravi, Briggs, Frank H., Goeke, Robert F., Tingay, Steven J., Johnston-Hollitt, Melanie, R, Gopalakrishna M, Morgan, Edward H., Pathikulangara, Joseph, Bunton, John D., Hampson, Grant, Williams, Christopher, Ord, Stephen M., Wayth, Randall B., Kumar, Deepak, Morales, Miguel F., deSouza, Ludi, Kratzenberg, Eric, Pallot, D., McWhirter, Russell, Hazelton, Bryna J., Arcus, Wayne, Barnes, David G., Bernardi, Gianni, Booler, T., Bowman, Judd D., Cappallo, Roger J., Corey, Brian E., Greenhill, Lincoln J., Herne, David, Hewitt, Jacqueline N., Kaplan, David L., Kasper, Justin C., Kincaid, Barton B., Koenig, Ronald, Lonsdale, Colin J., Lynch, Mervyn J., Mitchell, Daniel A., Oberoi, Divya, Remillard, Ronald A., Rogers, Alan E., Salah, Joseph E., Sault, Robert J., Stevens, Jamie B., Tremblay, S. E., Webster, Rachel L., Whitney, Alan R., and Wyithe, Stuart B.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

An FPGA-based digital-receiver has been developed for a low-frequency imaging radio interferometer, the Murchison Widefield Array (MWA). The MWA, located at the Murchison Radio-astronomy Observatory (MRO) in Western Australia, consists of 128 dual-polarized aperture-array elements (tiles) operating between 80 and 300\,MHz, with a total processed bandwidth of 30.72 MHz for each polarization. Radio-frequency signals from the tiles are amplified and band limited using analog signal conditioning units; sampled and channelized by digital-receivers. The signals from eight tiles are processed by a single digital-receiver, thus requiring 16 digital-receivers for the MWA. The main function of the digital-receivers is to digitize the broad-band signals from each tile, channelize them to form the sky-band, and transport it through optical fibers to a centrally located correlator for further processing. The digital-receiver firmware also implements functions to measure the signal power, perform power equalization across the band, detect interference-like events, and invoke diagnostic modes. The digital-receiver is controlled by high-level programs running on a single-board-computer. This paper presents the digital-receiver design, implementation, current status, and plans for future enhancements., Comment: 14 pages, 7 figures

Published
2015
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2. A study of fundamental limitations to statistical detection of redshifted HI from the epoch of reionization

Author

Thyagarajan, Nithyanandan, Shankar, N. Udaya, Subrahmanyan, Ravi, Arcus, Wayne, Bernardi, Gianni, Bowman, Judd D., Briggs, Frank, Bunton, John D., Cappallo, Roger J., Corey, Brian E., deSouza, Ludi, Emrich, David, Gaensler, Bryan M., Goeke, Robert F., Greenhill, Lincoln J., Hazelton, Bryna J., Herne, David, Hewitt, Jacqueline N., Johnston-Hollitt, Melanie, Kaplan, David L., Kasper, Justin C., Kincaid, Barton B., Koenig, Ronald, Kratzenberg, Eric, Lonsdale, Colin J., Lynch, Mervyn J., McWhirter, S. Russell, Mitchell, Daniel A., Morales, Miguel F., Morgan, Edward H., Oberoi, Divya, Ord, Stephen M., Pathikulangara, Joseph, Remillard, Ronald A., Rogers, Alan E. E., Roshi, Anish A., Salah, Joseph E., Sault, Robert J., Srivani, K. S., Stevens, Jamie B., Thiagaraj, Prabu, Tingay, Steven J., Wayth, Randall B., Waterson, Mark, Webster, Rachel L., Whitney, Alan R., Williams, Andrew J., Williams, Christopher L., and Wyithe, J. Stuart B.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

In this paper we explore for the first time the relative magnitudes of three fundamental sources of uncertainty, namely, foreground contamination, thermal noise and sample variance in detecting the HI power spectrum from the Epoch of Reionization (EoR). We derive limits on the sensitivity of a Fourier synthesis telescope to detect EoR based on its array configuration and a statistical representation of images made by the instrument. We use the Murchison Widefield Array (MWA) configuration for our studies. Using a unified framework for estimating signal and noise components in the HI power spectrum, we derive an expression for and estimate the contamination from extragalactic point-like sources in three-dimensional k-space. Sensitivity for EoR HI power spectrum detection is estimated for different observing modes with MWA. With 1000 hours of observing on a single field using the 128-tile MWA, EoR detection is feasible (S/N > 1 for $k\lesssim 0.8$ Mpc$^{-1}$). Bandpass shaping and refinements to the EoR window are found to be effective in containing foreground contamination, which makes the instrument tolerant to imaging errors. We find that for a given observing time, observing many independent fields of view does not offer an advantage over a single field observation when thermal noise dominates over other uncertainties in the derived power spectrum., Comment: 19 pages, 14 figures (19 figures in total including subfigures), 2 appendices, in press for publication in ApJ

Published
2013
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3. Science with the Murchison Widefield Array

Author

Bowman, Judd D., Cairns, Iver, Kaplan, David L., Murphy, Tara, Oberoi, Divya, Staveley-Smith, Lister, Arcus, Wayne, Barnes, David G., Bernardi, Gianni, Briggs, Frank H., Brown, Shea, Bunton, John D., Burgasser, Adam J., Cappallo, Roger J., Chatterjee, Shami, Corey, Brian E., Coster, Anthea, Deshpande, Avinash, deSouza, Ludi, Emrich, David, Erickson, Philip, Goeke, Robert F., Gaensler, B. M., Greenhill, Lincoln J., Harvey-Smith, Lisa, Hazelton, Bryna J., Herne, David, Hewitt, Jacqueline N., Johnston-Hollitt, Melanie, Kasper, Justin C., Kincaid, Barton B., Koenig, Ronald, Kratzenberg, Eric, Lonsdale, Colin J., Lynch, Mervyn J., Matthews, Lynn D., McWhirter, S. Russell, Mitchell, Daniel A., Morales, Miguel F., Morgan, Edward H., Ord, Stephen M., Pathikulangara, Joseph, Thiagaraj, Prabu, Remillard, Ronald A., Robishaw, Timothy, Rogers, Alan E. E., Roshi, Anish A., Salah, Joseph E., Sault, Robert J., Shankar, N. Udaya, Srivani, K. S., Stevens, Jamie B., Subrahmanyan, Ravi, Tingay, Steven J., Wayth, Randall B., Waterson, Mark, Webster, Rachel L., Whitney, Alan R., Williams, Andrew J., Williams, Christopher L., and Wyithe, J. Stuart B.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics
Abstract

Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the Southern Hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21 cm emission from the epoch of reionisation in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives., Comment: Updated with revisions. 32 pages including figures and references. Submitted to PASA

Published
2012
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4. Fast Holographic Deconvolution: a new technique for precision radio interferometry

Author

Sullivan, Ian, Morales, Miguel, Hazelton, Bryna, Arcus, Wayne, Barnes, David, Bernardi, Gianni, Briggs, Frank, Bowman, Judd D., Bunton, John, Cappallo, Roger, Corey, Brian, Deshpande, Avinash, deSouza, Ludi, Emrich, David, Gaensler, B. M., Goeke, Robert, Greenhill, Lincoln, Herne, David, Hewitt, Jacqueline, Johnston-Hollitt, Melanie, Kaplan, David, Kasper, Justin, Kincaid, Barton, Koenig, Ronald, Kratzenberg, Eric, Lonsdale, Colin, Lynch, Mervyn, McWhirter, Russell, Mitchell, Daniel, Morgan, Edward, Oberoi, Divya, Ord, Stephen, Pathikulangara, Joseph, Prabu, Thiagaraj, Remillard, Ron, Rogers, Alan, Roshi, Anish, Salah, Joseph, Sault, Robert, Shankar, Udaya, Srivani, K., Stevens, Jamie, Subrahmanyan, Ravi, Tingay, Steven, Wayth, Randall, Waterson, Mark, Webster, Rachel, Whitney, Alan, Williams, Andrew, Williams, Chris, and Wyithe, Stuart

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract

We introduce the Fast Holographic Deconvolution method for analyzing interferometric radio data. Our new method is an extension of A-projection/software-holography/forward modeling analysis techniques and shares their precision deconvolution and widefield polarimetry, while being significantly faster than current implementations that use full direction-dependent antenna gains. Using data from the MWA 32 antenna prototype, we demonstrate the effectiveness and precision of our new algorithm. Fast Holographic Deconvolution may be particularly important for upcoming 21 cm cosmology observations of the Epoch of Reionization and Dark Energy where foreground subtraction is intimately related to the precision of the data reduction., Comment: ApJ accepted

Published
2012
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5. Low Frequency Imaging of Fields at High Galactic Latitude with the Murchison Widefield Array 32-Element Prototype

Author

Williams, Christopher L., Hewitt, Jacqueline N., Levine, Alan M., de Oliveira-Costa, Angelica, Bowman, Judd D., Briggs, Frank H., Gaensler, B. M., Hernquist, Lars L., Mitchell, Daniel A., Morales, Miguel F., Sethi, Shiv K., Subrahmanyan, Ravi, Sadler, Elaine M., Arcus, Wayne, Barnes, David G., Bernardi, Gianni, Bunton, John D., Cappallo, Roger C., Crosse, Brian W., Corey, Brian E., Deshpande, Avinash, deSouza, Ludi, Emrich, David, Goeke, Robert F., Greenhill, Lincoln J., Hazelton, Bryna J., Herne, David, Kaplan, David L., Kasper, Justin C., Kincaid, Barton B., Koenig, Ronald, Kratzenberg, Eric, Lonsdale, Colin J., Lynch, Mervyn J., McWhirter, S. Russell, Mitchell, %Daniel A., Morales, %Miguel F., Morgan, Edward H., Oberoi, Divya, Ord, Stephen M., Pathikulangara, Joseph, Prabu, Thiagaraj, Remillard, Ronald A., Rogers, Alan E. E., Roshi, Anish A., Salah, Joseph E., Sault, Robert J., Shankar, N. Udaya, Srivani, K. S., Stevens, Jamie B., Tingay, Steven J., Wayth, Randall B., Waterson, Mark, Webster, Rachel L., Whitney, Alan R., Williams, Andrew J., and Wyithe, J. Stuart B.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The Murchison Widefield Array (MWA) is a new low-frequency, wide field-of-view radio interferometer under development at the Murchison Radio-astronomy Observatory (MRO) in Western Australia. We have used a 32-element MWA prototype interferometer (MWA-32T) to observe two 50-degree diameter fields in the southern sky in the 110 MHz to 200 MHz band in order to evaluate the performance of the MWA-32T, to develop techniques for epoch of reionization experiments, and to make measurements of astronomical foregrounds. We developed a calibration and imaging pipeline for the MWA-32T, and used it to produce ~15' angular resolution maps of the two fields. We perform a blind source extraction using these confusion-limited images, and detect 655 sources at high significance with an additional 871 lower significance source candidates. We compare these sources with existing low-frequency radio surveys in order to assess the MWA-32T system performance, wide field analysis algorithms, and catalog quality. Our source catalog is found to agree well with existing low-frequency surveys in these regions of the sky and with statistical distributions of point sources derived from Northern Hemisphere surveys; it represents one of the deepest surveys to date of this sky field in the 110 MHz to 200 MHz band., Comment: 20 pages, 6 tables, 12 figures. 1 online-only machine readable table. Submitted to ApJ

Published
2012
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6. First Spectroscopic Imaging Observations of the Sun at Low Radio Frequencies with the Murchison Widefield Array Prototype

Author

Oberoi, Divya, Matthews, Lynn D., Cairns, Iver H., Emrich, David, Lobzin, Vasili, Lonsdale, Colin J., Morgan, Edward H., Prabu, T., Vedantham, Harish, Wayth, Randall B., Williams, Andrew, Williams, Christopher, White, Stephen M., Allen, G., Arcus, Wayne, Barnes, David, Benkevitch, Leonid, Bernardi, Gianni, Bowman, Judd D., Briggs, Frank H., Bunton, John D., Burns, Steve, Cappallo, Roger C., Clark, M. A., Corey, Brian E., Dawson, M., DeBoer, David, De Gans, A., deSouza, Ludi, Derome, Mark, Edgar, R. G., Elton, T., Goeke, Robert, Gopalakrishna, M. R., Greenhill, Lincoln J., Hazelton, Bryna, Herne, David, Hewitt, Jacqueline N., Kamini, P. A., Kaplan, David L., Kasper, Justin C., Kennedy, Rachel, Kincaid, Barton B., Kocz, Jonathan, Koeing, R., Kowald, Errol, Lynch, Mervyn J., Madhavi, S., McWhirter, Stephen R., Mitchell, Daniel A., Morales, Miguel F., Ng, A., Ord, Stephen M., Pathikulangara, Joseph, Rogers, Alan E. E., Roshi, Anish, Salah, Joseph E., Sault, Robert J., Schinckel, Antony, Shankar, N. Udaya, Srivani, K. S., Stevens, Jamie, Subrahmanyan, Ravi, Thakkar, D., Tingay, Steven J., Tuthill, J., Vaccarella, Annino, Waterson, Mark, Webster, Rachel L., and Whitney, Alan R.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present the first spectroscopic images of solar radio transients from the prototype for the Murchison Widefield Array (MWA), observed on 2010 March 27. Our observations span the instantaneous frequency band 170.9-201.6 MHz. Though our observing period is characterized as a period of `low' to `medium' activity, one broadband emission feature and numerous short-lived, narrowband, non-thermal emission features are evident. Our data represent a significant advance in low radio frequency solar imaging, enabling us to follow the spatial, spectral, and temporal evolution of events simultaneously and in unprecedented detail. The rich variety of features seen here reaffirms the coronal diagnostic capability of low radio frequency emission and provides an early glimpse of the nature of radio observations that will become available as the next generation of low frequency radio interferometers come on-line over the next few years., Comment: 15 pages, 5 figures, accepted for publication in Astrophysical Journal Letters. Movies for figures 4 and 5 available at http://www.mwatelescope.org/info/mwa_proto.html

Published
2011
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7. The Precision Array for Probing the Epoch of Reionization: 8 Station Results

Author

Parsons, Aaron R., Backer, Donald C., Bradley, Richard F., Aguirre, James E., Benoit, Erin E., Carilli, Chris L., Foster, Griffin S., Gugliucci, Nicole E., Herne, David, Jacobs, Daniel C., Lynch, Mervyn J., Manley, Jason R., Parashare, Chaitali R., Werthimer, Daniel J., and Wright, Melvyn C. H.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We are developing the Precision Array for Probing the Epoch of Reionization (PAPER) to detect 21cm emission from the early Universe, when the first stars and galaxies were forming. We describe the overall experiment strategy and architecture and summarize two PAPER deployments: a 4-antenna array in the low-RFI environment of Western Australia and an 8-antenna array at our prototyping site in Green Bank, WV. From these activities we report on system performance, including primary beam model verification, dependence of system gain on ambient temperature, measurements of receiver and overall system temperatures, and characterization of the RFI environment at each deployment site. We present an all-sky map synthesized between 139 MHz and 174 MHz using data from both arrays that reaches down to 80 mJy (4.9 K, for a beam size of 2.15e-5 steradians at 154 MHz), with a 10 mJy (620 mK) thermal noise level that indicates what would be achievable with better foreground subtraction. We calculate angular power spectra ($C_\ell$) in a cold patch and determine them to be dominated by point sources, but with contributions from galactic synchrotron emission at lower radio frequencies and angular wavemodes. Although the cosmic variance of foregrounds dominates errors in these power spectra, we measure a thermal noise level of 310 mK at $\ell=100$ for a 1.46-MHz band centered at 164.5 MHz. This sensitivity level is approximately three orders of magnitude in temperature above the level of the fluctuations in 21cm emission associated with reionization., Comment: 13 pages, 14 figures, submitted to AJ. Revision 2 corrects a scaling error in the x axis of Fig. 12 that lowers the calculated power spectrum temperature

Published
2009
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8. The Murchison Widefield Array: Design Overview

Author

Lonsdale, Colin J., Cappallo, Roger J., Morales, Miguel F., Briggs, Frank H., Benkevitch, Leonid, Bowman, Judd D., Bunton, John D., Burns, Steven, Corey, Brian E., deSouza, Ludi, Doeleman, Sheperd S., Derome, Mark, Deshpande, Avinash, Gopalakrishna, M. R., Greenhill, Lincoln J., Herne, David, Hewitt, Jacqueline N., Kamini, P. A., Kasper, Justin C., Kincaid, Barton B., Kocz, Jonathan, Kowald, Errol, Kratzenberg, Eric, Kumar, Deepak, Lynch, Mervyn J., Madhavi, S., Matejek, Michael, Mitchell, Daniel, Morgan, Edward, Oberoi, Divya, Ord, Steven, Pathikulangara, Joseph, Prabu, T., Rogers, Alan E. E., Roshi, Anish, Salah, Joseph E., Sault, Robert J., Shankar, N. Udaya, Srivani, K. S., Stevens, Jamie, Tingay, Steven, Vaccarella, Annino, Waterson, Mark, Wayth, Randall B., Webster, Rachel L., Whitney, Alan R., Williams, Andrew, and Williams, Christopher

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

The Murchison Widefield Array (MWA) is a dipole-based aperture array synthesis telescope designed to operate in the 80-300 MHz frequency range. It is capable of a wide range of science investigations, but is initially focused on three key science projects. These are detection and characterization of 3-dimensional brightness temperature fluctuations in the 21cm line of neutral hydrogen during the Epoch of Reionization (EoR) at redshifts from 6 to 10, solar imaging and remote sensing of the inner heliosphere via propagation effects on signals from distant background sources,and high-sensitivity exploration of the variable radio sky. The array design features 8192 dual-polarization broad-band active dipoles, arranged into 512 tiles comprising 16 dipoles each. The tiles are quasi-randomly distributed over an aperture 1.5km in diameter, with a small number of outliers extending to 3km. All tile-tile baselines are correlated in custom FPGA-based hardware, yielding a Nyquist-sampled instantaneous monochromatic uv coverage and unprecedented point spread function (PSF) quality. The correlated data are calibrated in real time using novel position-dependent self-calibration algorithms. The array is located in the Murchison region of outback Western Australia. This region is characterized by extremely low population density and a superbly radio-quiet environment,allowing full exploitation of the instrumental capabilities., Comment: 9 pages, 5 figures, 1 table. Accepted for publication in Proceedings of the IEEE

Published
2009
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9. Detection of Crab Giant Pulses Using the Mileura Widefield Array Low Frequency Demonstrator Field Prototype System

Author

Bhat, N. D. Ramesh, Wayth, Randall B., Knight, Haydon S., Bowman, Judd D., Oberoi, Divya, Barnes, David G., Briggs, Frank H., Cappallo, Roger J., Herne, David, Kocz, Jonathon, Lonsdale, Colin J., Lynch, Mervyn J., Stansby, Bruce, Stevens, Jamie, Torr, Glen, Webster, Rachel L., and Wyithe, J. Stuart B.

Subjects
Astrophysics
Abstract

We report on the detection of giant pulses from the Crab Nebula pulsar at a frequency of 200 MHz using the field deployment system designed for the Mileura Widefield Array's Low Frequency Demonstrator (MWA-LFD). Our observations are among the first high-quality detections at such low frequencies. The measured pulse shapes are deconvolved for interstellar pulse broadening, yielding a pulse-broadening time of 670$\pm$100 $\mu$s, and the implied strength of scattering (scattering measure) is the lowest that is estimated towards the Crab nebula from observations made so far. The sensitivity of the system is largely dictated by the sky background, and our simple equipment is capable of detecting pulses that are brighter than $\sim$9 kJy in amplitude. The brightest giant pulse detected in our data has a peak amplitude of $\sim$50 kJy, and the implied brightness temperature is $10^{31.6}$ K. We discuss the giant pulse detection prospects with the full MWA-LFD system. With a sensitivity over two orders of magnitude larger than the prototype equipment, the full system will be capable of detecting such bright giant pulses out to a wide range of Galactic distances; from $\sim$8 to $\sim$30 kpc depending on the frequency. The MWA-LFD will thus be a highly promising instrument for the studies of giant pulses and other fast radio transients at low frequencies., Comment: 10 pages, 6 figures, Accepted for publication in the Astrophysical Journal

Published
2007
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10. Field Deployment of Prototype Antenna Tiles for the Mileura Widefield Array--Low Frequency Demonstrator

Author

Bowman, Judd D., Barnes, David G., Briggs, Frank H., Corey, Brian E., Lynch, Merv J., Bhat, N. D. Ramesh, Cappallo, Roger J., Doeleman, Sheperd S., Fanous, Brian J., Herne, David, Hewitt, Jacqueline N., Johnston, Chris, Kasper, Justin C., Kocz, Jonathon, Kratzenberg, Eric, Lonsdale, Colin J., Morales, Miguel F., Oberoi, Divya, Salah, Joseph E., Stansby, Bruce, Stevens, Jamie, Torr, Glen, Wayth, Randall, Webster, Rachel L., and Wyithe, J. Stuart B.

Subjects
Astrophysics
Abstract

Experiments were performed with prototype antenna tiles for the Mileura Widefield Array--Low Frequency Demonstrator (MWA-LFD) to better understand the widefield, wideband properties of their design and to characterize the radio frequency interference (RFI) between 80 and 300 MHz at the site in Western Australia. Observations acquired during the six month deployment confirmed the predicted sensitivity of the antennas, sky-noise dominated system temperatures, and phase-coherent interferometric measurements. The radio spectrum is remarkably free of strong terrestrial signals, with the exception of two narrow frequency bands allocated to satellite downlinks and rare bursts due to ground-based transmissions being scattered from aircraft and meteor trails. Results indicate the potential of the MWA-LFD to make significant achievements in its three key science objectives: epoch of reionziation science, heliospheric science, and radio transient detection., Comment: Accepted by AJ. 17 pages with figures

Published
2006
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13. The Australian Mid-latitude Continental Ionosphere with Respect to Low-frequency Radio Astronomy

Author

Herne, David Edwin and Herne, David Edwin

Abstract

The ionosphere above the Murchison Radio Observatory (MRO) has been characterised over half of solar cycle 24 and its response to impinging low-frequency radio waves described. The outcomes of this thesis will contribute to an operational requirement of the Murchison WideField Array (MWA) radio telescope (calibration) and delivery of the project’s scientific goals (high fidelity imaging) and shows that the MRO site is an excellent location from which to conduct low-frequency radio astronomy.

Published
2016

14. A digital-receiver for the MurchisonWidefield Array

Author

Prabu, Thiagaraj, primary, Srivani, K. S., additional, Roshi, D. Anish, additional, Kamini, P. A., additional, Madhavi, S., additional, Emrich, David, additional, Crosse, Brian, additional, Williams, Andrew J., additional, Waterson, Mark, additional, Deshpande, Avinash A., additional, Shankar, N. Udaya, additional, Subrahmanyan, Ravi, additional, Briggs, Frank H., additional, Goeke, Robert F., additional, Tingay, Steven J., additional, Johnston-Hollitt, Melanie, additional, R, Gopalakrishna M, additional, Morgan, Edward H., additional, Pathikulangara, Joseph, additional, Bunton, John D., additional, Hampson, Grant, additional, Williams, Christopher, additional, Ord, Stephen M., additional, Wayth, Randall B., additional, Kumar, Deepak, additional, Morales, Miguel F., additional, deSouza, Ludi, additional, Kratzenberg, Eric, additional, Pallot, D., additional, McWhirter, Russell, additional, Hazelton, Bryna J., additional, Arcus, Wayne, additional, Barnes, David G., additional, Bernardi, Gianni, additional, Booler, T., additional, Bowman, Judd D., additional, Cappallo, Roger J., additional, Corey, Brian E., additional, Greenhill, Lincoln J., additional, Herne, David, additional, Hewitt, Jacqueline N., additional, Kaplan, David L., additional, Kasper, Justin C., additional, Kincaid, Barton B., additional, Koenig, Ronald, additional, Lonsdale, Colin J., additional, Lynch, Mervyn J., additional, Mitchell, Daniel A., additional, Oberoi, Divya, additional, Remillard, Ronald A., additional, Rogers, Alan E., additional, Salah, Joseph E., additional, Sault, Robert J., additional, Stevens, Jamie B., additional, Tremblay, S., additional, Webster, Rachel L., additional, Whitney, Alan R., additional, and Wyithe, Stuart B., additional

Published
2015
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15. Health and social care. Book 2. Level 3. BTEC National

Author

Billingham, Marilyn, Davenport, Pamela, Herne, David, Mckie, Stuart, Snaith, Marjorie, and Talman, Hilary

Subjects
formación profesional, lengua inglesa, salud pública, educación sanitaria, medios de enseñanza, secundaria segundo ciclo, proyecto bilingüe, servicio social, cuidado de niños, Reino Unido, programa de enseñanza
Abstract

Recurso preparado para ayudar al alumno en el curso BTEC National, nivel 3 en salud y asistencia social. El programa BTEC, es un programa de estudios que permite obtener una cualificación profesional o laboral. Incluye las siguientes unidades: los valores y la planificación de la atención social; el cuidado de los niños y jóvenes; la protección de los adultos y la promoción de la independencia; salud pública; fisiología del balance de fluidos; desórdenes fisiológicos; aplicación de perspectivas sociológicas a la salud y asistencia social, y promoción de la educación sanitaria. Incluye actividades de evaluación en cada unidad que cubren todos los criterios de ésta para ofrecer a los estudiantes la oportunidad de practicar sus tareas y profundizar en el conocimiento y la comprensión de la materia. SC Biblioteca de Educación del Ministerio de Educación, Cultura y Deporte; Calle San Agustín, 5 - 3 planta; 28014 Madrid; Tel. +34917748000; biblioteca@mecd.es GBR

Published
2010

16. Ionospheric Phenomena and Low-Frequency Radio Astronomy

Author

Australian Space Science Conference, Herne, David, Kennewell, J., Lynch, Mervyn, Carrano, C., Australian Space Science Conference, Herne, David, Kennewell, J., Lynch, Mervyn, and Carrano, C.

Abstract

The Murchison Widefield Array radio telescope (MWA), situated on the Murchison Radio Observatory (MRO) in Western Australia, has recently commenced operations. This instrument operates over the frequency range 80-300 MHz. Further, the MRO is also the site chosen to host the low-frequency component of the Square Kilometre Array, radio telescope (SKA). Each instrument is susceptible to scintillation caused by fluctuations in ionospheric plasma density and Faraday rotation of incoming signals caused by the interaction of low-frequency radio waves with dissociated electrons in the ionosphere. Observations of these parameters over several years, across periods of both subdued and elevated solar activity have demonstrated markedly differing regimes. High-precision GPS systems, combined with purpose-written data acquisition software (SCINDA), have enabled investigation of various phenomena including the effect of solar storms on the ionosphere at highly resolved time-scales. We report on aspects of phenomena observed and their significance to low-frequency radio astronomy and note that conditions of very low scintillation encountered support the decision to site world-leading instruments on the MRO.

Published
2014

17. Low-Frequency Observations of the Moon with the Murchison Widefield Array

Author

McKinley, B., Briggs, Frank, Kaplan, D., Greenhill, L., Bernardi, G., Bowman, Judd, de Oliveira-Costa, A., Tingay, Steven, Gaensler, B., Oberoi, Divya, Johnston-Hollitt, M., Arcus, Wayne, Barnes, D., Bunton, John, Cappallo, Roger, Corey, Brian, Deshpande, Avinash, DeSouza, Ludi, Emrich, D., Goeke, Robert, Hazelton, Bryna, Herne, David, Hewitt, Jacqueline, Kasper, Justin, Kincaid, Barton, Koenig, R., Kratzenberg, Eric, Lonsdale, Colin, McWhirter, S., Mitchell, D., Morales, Miguel, Morgan, Edward, Ord, Stephen, Pathikulangara, Joseph, Prabu, T., Remillard, Ron, Rogers, Alan, Roshi, Anish, Salah, J., Sault, Robert, Shankar, N Udaya, Srivani, K., Stevens, J., Subrahmanyan, R., Wayth, R., Waterson, Mark, Webster, Rachel, Whitney, Alan, Williams, A., Williams, C., Wyithe, J., McKinley, B., Briggs, Frank, Kaplan, D., Greenhill, L., Bernardi, G., Bowman, Judd, de Oliveira-Costa, A., Tingay, Steven, Gaensler, B., Oberoi, Divya, Johnston-Hollitt, M., Arcus, Wayne, Barnes, D., Bunton, John, Cappallo, Roger, Corey, Brian, Deshpande, Avinash, DeSouza, Ludi, Emrich, D., Goeke, Robert, Hazelton, Bryna, Herne, David, Hewitt, Jacqueline, Kasper, Justin, Kincaid, Barton, Koenig, R., Kratzenberg, Eric, Lonsdale, Colin, McWhirter, S., Mitchell, D., Morales, Miguel, Morgan, Edward, Ord, Stephen, Pathikulangara, Joseph, Prabu, T., Remillard, Ron, Rogers, Alan, Roshi, Anish, Salah, J., Sault, Robert, Shankar, N Udaya, Srivani, K., Stevens, J., Subrahmanyan, R., Wayth, R., Waterson, Mark, Webster, Rachel, Whitney, Alan, Williams, A., Williams, C., and Wyithe, J.

Abstract

A new generation of low-frequency radio telescopes is seeking to observe the redshifted 21 cm signal from the epoch of reionization (EoR), requiring innovative methods of calibration and imaging to overcome the difficulties of wide-field low-frequency radio interferometry. Precise calibration will be required to separate the expected small EoR signal from the strong foreground emission at the frequencies of interest between 80 and 300 MHz. The Moon may be useful as a calibration source for detection of the EoR signature, as it should have a smooth and predictable thermal spectrum across the frequency band of interest. Initial observations of the Moon with the Murchison Widefield Array 32 tile prototype show that the Moon does exhibit a similar trend to that expected for a cool thermally emitting body in the observed frequency range, but that the spectrum is corrupted by reflected radio emission from Earth. In particular, there is an abrupt increase in the observed flux density of the Moon within the internationally recognized frequency modulated (FM) radio band. The observations have implications for future low-frequency surveys and EoR detection experiments that will need to take this reflected emission from the Moon into account. The results also allow us to estimate the equivalent isotropic power emitted by the Earth in the FM band and to determine how bright the Earth might appear at meter wavelengths to an observer beyond our own solar system.

Published
2013

18. A study of fundamental limitations to statistical detection of redshifted H I from the epoch of reionization

Author

Thyagarajan, Nithyanandan, Udaya Shankar, N., Subrahmanyan, Ravi, Arcus, Wayne, Bernardi, Gianni, Bowman, Judd, Briggs, Frank, Bunton, John, Cappallo, Roger, Corey, Brian, deSouza, Ludi, Emrich, David, Gaensler, Brian, Goeke, Robert, Greenhill, Lincoln, Hazelton, Bryna, Herne, David, Hewitt, Jacqueline, Johnston-Hollitt, Melanie, Kaplan, David, Kasper, Justin, Kincaid, Barton, Koenig, Ronald, Kratzenberg, Eric, Lonsdale, Colin, Lynch, Mervyn, McWhirter, S. Russell, Mitchell, Daniel, Morales, Miguel, Morgan, Edward, Oberoi, Divya, Ord, Stephen, Pathikulangara, Joseph, Remillard, Ronald, Rogers, Alan, Roshi, D. Anish, Salah, Joseph, Sault, Robert, Srivani, K., Stevens, Jamie, Thiagaraj, Prabu, Tingay, Steven, Wayth, Randall, Waterson, Mark, Webster, Rachel, Whitney, Alan, Williams, Andrew, Williams, Christopher, Wyithe, J. Stuart, Thyagarajan, Nithyanandan, Udaya Shankar, N., Subrahmanyan, Ravi, Arcus, Wayne, Bernardi, Gianni, Bowman, Judd, Briggs, Frank, Bunton, John, Cappallo, Roger, Corey, Brian, deSouza, Ludi, Emrich, David, Gaensler, Brian, Goeke, Robert, Greenhill, Lincoln, Hazelton, Bryna, Herne, David, Hewitt, Jacqueline, Johnston-Hollitt, Melanie, Kaplan, David, Kasper, Justin, Kincaid, Barton, Koenig, Ronald, Kratzenberg, Eric, Lonsdale, Colin, Lynch, Mervyn, McWhirter, S. Russell, Mitchell, Daniel, Morales, Miguel, Morgan, Edward, Oberoi, Divya, Ord, Stephen, Pathikulangara, Joseph, Remillard, Ronald, Rogers, Alan, Roshi, D. Anish, Salah, Joseph, Sault, Robert, Srivani, K., Stevens, Jamie, Thiagaraj, Prabu, Tingay, Steven, Wayth, Randall, Waterson, Mark, Webster, Rachel, Whitney, Alan, Williams, Andrew, Williams, Christopher, and Wyithe, J. Stuart

Abstract

In this paper, we explore for the first time the relative magnitudes of three fundamental sources of uncertainty, namely, foreground contamination, thermal noise, and sample variance, in detecting the H I power spectrum from the epoch of reionization (EoR). We derive limits on the sensitivity of a Fourier synthesis telescope to detect EoR based on its array configuration and a statistical representation of images made by the instrument. We use the Murchison Widefield Array (MWA) configuration for our studies. Using a unified framework for estimating signal and noise components in the H I power spectrum, we derive an expression for and estimate the contamination from extragalactic point-like sources in three-dimensional k-space. Sensitivity for EoR H I power spectrum detection is estimated for different observing modes with MWA. With 1000 hr of observing on a single field using the 128 tile MWA, EoR detection is feasible (S/N > 1 for k <~ 0.8 Mpc−1). Bandpass shaping and refinements to the EoR window are found to be effective in containing foreground contamination, which makes the instrument tolerant to imaging errors. We find that for a given observing time, observing many independent fields of view does not offer an advantage over a single field observation when thermal noise dominates over other uncertainties in the derived power spectrum.

Published
2013

19. The EoR sensitivity of the Murchison Widefield Array

Author

Arcus, Wayne, Emrich, David, Herne, David, Lynch, Mervyn, Tingay, Steven, Wayth, Randall, Waterson, Mark, Beardsley, A., Hazelton, B., Morales, M., Barnes, D., Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Gaensler, B., Goeke, R., Greenhill, L., Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., McWhirter, S., Mitchell, D., Morgan, E., Oberoi, D., Ord, S., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Sault, R., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Webster, R., Whitney, A., Williams, A., Williams, C., Wyithe, J., Arcus, Wayne, Emrich, David, Herne, David, Lynch, Mervyn, Tingay, Steven, Wayth, Randall, Waterson, Mark, Beardsley, A., Hazelton, B., Morales, M., Barnes, D., Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Gaensler, B., Goeke, R., Greenhill, L., Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., McWhirter, S., Mitchell, D., Morgan, E., Oberoi, D., Ord, S., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Sault, R., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Webster, R., Whitney, A., Williams, A., Williams, C., and Wyithe, J.

Abstract

Using the final 128 antenna locations of the Murchison Widefield Array (MWA), we calculate its sensitivity to the epoch of reionization (EoR) power spectrum of redshifted 21 cm emission for a fiducial model and provide the tools to calculate the sensitivity for any model. Our calculation takes into account synthesis rotation, chromatic and asymmetrical baseline effects, and excludes modes that will be contaminated by foreground subtraction. For the fiducial model, the MWA will be capable of a 14s detection of the EoR signal with one full season of observation on two fields (900 and 700 h).

Published
2013

20. The giant lobes of Centaurus A observed at 118MHz with the Murchison Widefield Array

Author

McKinley, B., Briggs, F., Gaensler, B., Feain, I., Bernardi, G., Wayth, Randall, Johnston-Hollitt, M., Offringa, A., Arcus, Wayne, Barnes, D., Bowman, J., Bunton, J., Capallo, R., Corey, B., Deshpande, A., deSouza, L., Emrich, David, Goeke, R., Greenhill, L., Hazelton, B., Herne, David, Hewitt, J., Kaplan, David, Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Oberoi, D., Ord, Stephen, Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, D., Salah, J., Sault, R., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Tingay, Steven, Waterson, Mark, Webster, R., Whitney, A., Williams, Andrew, Williams, C., Wyithe, J., McKinley, B., Briggs, F., Gaensler, B., Feain, I., Bernardi, G., Wayth, Randall, Johnston-Hollitt, M., Offringa, A., Arcus, Wayne, Barnes, D., Bowman, J., Bunton, J., Capallo, R., Corey, B., Deshpande, A., deSouza, L., Emrich, David, Goeke, R., Greenhill, L., Hazelton, B., Herne, David, Hewitt, J., Kaplan, David, Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Oberoi, D., Ord, Stephen, Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, D., Salah, J., Sault, R., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Tingay, Steven, Waterson, Mark, Webster, R., Whitney, A., Williams, Andrew, Williams, C., and Wyithe, J.

Abstract

We present new wide-field observations of Centaurus A (Cen A) and the surrounding region at 118MHz with the Murchison Widefield Array (MWA) 32-tile prototype, with which we investigate the spectral-index distribution of Cen A’s giant radio lobes. We compare our images to 1.4 GHz maps of Cen A and compute spectral indices using temperature–temperature plots and spectral tomography. We find that the morphologies at 118MHz and 1.4 GHz match very closely apart from an extra peak in the southern lobe at 118 MHz, which provides tentative evidence for the existence of a southern counterpart to the northern middle lobe of Cen A. Our spatially averaged spectral indices for both the northern and southern lobes are consistent with previous analyses, however we find significant spatial variation of the spectra across the extent of each lobe. Both the spectral-index distribution and the morphology at low radio frequencies support a scenario of multiple outbursts of activity from the central engine. Our results are consistent with inverse-Compton modelling of radio and gamma-ray data that support a value for the lobe age of between 10 and 80 Myr.

Published
2013

21. A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz

Author

Trott, Cathryn, Hurley-Walker, Natasha, Wayth, Randall, Macquart, Jean-Pierre, Arcus, Wayne, Emrich, David, Herne, David, Lynch, Mervyn, Ord, Stephen, Tingay, Steven, Waterson, Mark, Williams, Andrew, Bell, M., Murphy, T., Kaplan, D., Hancock, P., Gaensler, B., Banyer, J., Bannister, K., Barnes, D., Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Goeke, R., Greenhill, L., Hazelton, B., Hewitt, J., Johnston-Hollitt, M., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Sault, R., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Webster, R., Whitney, A., Williams, C., Wyithe, J., Trott, Cathryn, Hurley-Walker, Natasha, Wayth, Randall, Macquart, Jean-Pierre, Arcus, Wayne, Emrich, David, Herne, David, Lynch, Mervyn, Ord, Stephen, Tingay, Steven, Waterson, Mark, Williams, Andrew, Bell, M., Murphy, T., Kaplan, D., Hancock, P., Gaensler, B., Banyer, J., Bannister, K., Barnes, D., Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Goeke, R., Greenhill, L., Hazelton, B., Hewitt, J., Johnston-Hollitt, M., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Sault, R., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Webster, R., Whitney, A., Williams, C., and Wyithe, J.

Abstract

We present a search for transient and variable radio sources at 154 MHz with the Murchison Widefield Array 32-tile prototype. Fifty-one images were obtained that cover a field of view of 1430 deg2 centred on Hydra A. The observations were obtained over three days in 2010 March and three days in 2011 April and May. The mean cadence of the observations was 26 minutes and there was additional temporal information on day and year timescales. We explore the variability of a sample of 105 low frequency radio sources within the field. Four bright (S > 6 Jy) candidate variable radio sources were identified that displayed low levels of short timescale variability (26 minutes). We conclude that this variability is likely caused by simplifications in the calibration strategy or ionospheric effects. On the timescale of one year we find two sources that show significant variability. We attribute this variability to either refractive scintillation or intrinsic variability. No radio transients were identified and we place an upper limit on the surface density of sources p < 7.5 × 10-5 deg-2 with flux densities > 5.5 Jy, and characteristic timescales of both 26 minutes and one year.

Published
2013

22. The Murchison Widefield Array: solar science with the low frequency SKA Precursor

Author

Tingay, Steven, Oberoi, D., Cairns, I., Donea, A., Duffin, R., Arcus, Wayne, Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Emrich, David, Gaensler, B., Goeke, R., Greenhill, L., Hazelton, B., Herne, David, Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kennewell, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Ord, S., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Udaya-Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Waterson, Mark, Wayth, Randall, Webster, R., Whitney, A., Williams, A., Williams, C., Wyithe, J., Tingay, Steven, Oberoi, D., Cairns, I., Donea, A., Duffin, R., Arcus, Wayne, Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Emrich, David, Gaensler, B., Goeke, R., Greenhill, L., Hazelton, B., Herne, David, Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kennewell, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Ord, S., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Udaya-Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Waterson, Mark, Wayth, Randall, Webster, R., Whitney, A., Williams, A., Williams, C., and Wyithe, J.

Abstract

The Murchison Widefield Array is a low frequency (80 – 300 MHz) SKA Precursor, comprising 128 aperture array elements (known as tiles) distributed over an area of 3 km diameter. The MWA is located at the extraordinarily radio quiet Murchison Radioastronomy Observatory in the mid-west of Western Australia, the selected home for the Phase 1 and Phase 2 SKA low frequency arrays. The MWA science goals include: 1) detection of fluctuations in the brightness temperature of the diffuse redshifted 21 cm line of neutral hydrogen from the epoch of reionisation; 2) studies of Galactic and extragalactic processes based on deep, confusion-limited surveys of the full sky visible to the array; 3) time domain astrophysics through exploration of the variable radio sky; and 4) solar imaging and characterisation of the heliosphere and ionosphere via propagation effects on background radio source emission. This paper concentrates on the capabilities of the MWA for solar science and summarises some of the solar science results to date, in advance of the initial operation of the final instrument in 2013.

Published
2013

23. Science with the Murchison Widefield Array

Author

Arcus, Wayne, Emrich, David, Herne, David, Lynch, Mervyn, Ord, Stephen, Tingay, Steven, Wayth, Randall, Waterson, Mark, Bowman, Judd, Cairns, Iver, Kaplan, David, Murphy, Tara, Oberoi, Divya, Staveley-Smith, Lister, Barnes, David, Bernardi, Gianni, Briggs, Frank, Brown, Shea, Bunton, John, Burgasser, Adam, Cappallo, Roger, Chatterjee, Shami, Corey, Brian, Coster, Anthea, Deshpande, Avinash, DeSouza, Ludi, Erickson, Philip, Goeke, Robert, Gaensler, B.M., Greenhill, Lincoln, Harvey-Smith, Lisa, Hazelton, Bryna, Hewitt, Jacqueline, Johnston-Hollitt, Melanie, Kasper, Justin, Kincaid, Barton, Koenig, Ronald, Kratzenberg, Eric, Lonsdale, Colin, Matthews, Lynn, McWhirter, S. Russell, Mitchell, Daniel, Morales, Miguel, Morgan, Edward, Pathikulangara, Joseph, Prabu, Thiagaraj, Remillard, Ronald, Robishaw, Timothy, Rogers, Alan, Roshi, Anish, Salah, Joseph, Sault, Robert, Udaya Shankar, N., Srivani, K.S., Stevens, Jamie, Subrahmanyan, Ravi, Webster, Rachel, Whitney, Alan, Williams, Andrew, Williams, Christopher, Wyithe, J. Stuart, Arcus, Wayne, Emrich, David, Herne, David, Lynch, Mervyn, Ord, Stephen, Tingay, Steven, Wayth, Randall, Waterson, Mark, Bowman, Judd, Cairns, Iver, Kaplan, David, Murphy, Tara, Oberoi, Divya, Staveley-Smith, Lister, Barnes, David, Bernardi, Gianni, Briggs, Frank, Brown, Shea, Bunton, John, Burgasser, Adam, Cappallo, Roger, Chatterjee, Shami, Corey, Brian, Coster, Anthea, Deshpande, Avinash, DeSouza, Ludi, Erickson, Philip, Goeke, Robert, Gaensler, B.M., Greenhill, Lincoln, Harvey-Smith, Lisa, Hazelton, Bryna, Hewitt, Jacqueline, Johnston-Hollitt, Melanie, Kasper, Justin, Kincaid, Barton, Koenig, Ronald, Kratzenberg, Eric, Lonsdale, Colin, Matthews, Lynn, McWhirter, S. Russell, Mitchell, Daniel, Morales, Miguel, Morgan, Edward, Pathikulangara, Joseph, Prabu, Thiagaraj, Remillard, Ronald, Robishaw, Timothy, Rogers, Alan, Roshi, Anish, Salah, Joseph, Sault, Robert, Udaya Shankar, N., Srivani, K.S., Stevens, Jamie, Subrahmanyan, Ravi, Webster, Rachel, Whitney, Alan, Williams, Andrew, Williams, Christopher, and Wyithe, J. Stuart

Abstract

Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the southern hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21-cm emission from the EoR in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.

Published
2013

24. Fast Holographic Deconvolution: A New Technique for Precision Radio Interferometry

Author

Sullivan, I., Morales, M., Hazelton, B., Arcus, Wayne, Barnes, D., Bernardi, G., Briggs, F., Bowman, J., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., DeSouza, L., Emrich, David, Gaensler, B., Goeke, R., Greenhill, L., Herne, David, Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Mitchell, D., Morgan, E., Oberoi, D., Ord, Stephen, Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Salah, J., Sault, R., Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Tingay, Steven, Wayth, Randall, Waterson, Mark, Webster, R., Whitney, A., Sullivan, I., Morales, M., Hazelton, B., Arcus, Wayne, Barnes, D., Bernardi, G., Briggs, F., Bowman, J., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., DeSouza, L., Emrich, David, Gaensler, B., Goeke, R., Greenhill, L., Herne, David, Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Mitchell, D., Morgan, E., Oberoi, D., Ord, Stephen, Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Salah, J., Sault, R., Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Tingay, Steven, Wayth, Randall, Waterson, Mark, Webster, R., and Whitney, A.

Abstract

We introduce the Fast Holographic Deconvolution method for analyzing interferometric radio data. Our new method is an extension of A-projection/software-holography/forward modeling analysis techniques and shares their precision deconvolution and wide-field polarimetry, while being significantly faster than current implementations that use full direction-dependent antenna gains. Using data from the MWA 32 antenna prototype, we demonstrate the effectiveness and precision of our new algorithm. Fast Holographic Deconvolution may be particularly important for upcoming 21 cm cosmology observations of the Epoch of Reionization and Dark Energy where foreground subtraction is intimately related to the precision of the data reduction.

Published
2012

25. Realisation of a low frequency SKA Precursor: The Murchison Widefield Array

Author

Tingay, Steven, Emrich, David, Ord, Stephen, Crosse, Brian, Arcus, Wayne, Colegate, Timothy, Hall, Peter, Herne, David, Lynch, Mervyn, Schlagenhaufer, Franz, Tremblay, Steven, Wayth, Randall, Waterson, Mark, Williams, Andrew, Tingay, Steven, Emrich, David, Ord, Stephen, Crosse, Brian, Arcus, Wayne, Colegate, Timothy, Hall, Peter, Herne, David, Lynch, Mervyn, Schlagenhaufer, Franz, Tremblay, Steven, Wayth, Randall, Waterson, Mark, and Williams, Andrew

Abstract

The Murchison Widefield Array is a low frequency (80 - 300 MHz) SKA Precursor, comprising 128 aperture array elements distributed over an area of 3 km diameter. The MWA is located at the extraordinarily radio quiet Murchison Radioastronomy Observatory in the mid-west of Western Australia, the selected home for the Phase 1 and Phase 2 SKA low frequency arrays. The MWA science goals include: 1) detection of fluctuations in the brightness temperature of the diffuse redshifted 21 cm line of neutral hydrogen from the epoch of reionisation; 2) studies of Galactic and extragalactic processes based on deep, confusion-limited surveys of the full sky visible to the array; 3) time domain astrophysics through exploration of the variable radio sky; and 4) solar imaging and characterisation of the heliosphere and ionosphere via propagation effects on background radio source emission. This paper will focus on a brief discussion of the as-built MWA system, highlighting several novel characteristics of the instrument, and a brief progress report (as of June 2012) on the final construction phase. Practical completion of the MWA is expected in November 2012, with commissioning commencing from approximately August 2012 and operations commencing near mid 2013. A brief description of recent science results from the MWA prototype instrument is given.

Published
2012

26. Low-Frequency Imaging of Fields at High Galactic Latitude with the Murchison Widefield Array 32 Element Prototype

Author

Williams, C., Hewitt, J., Levine, A., de Oliveira-Costa, A., Bowman, Judd, Briggs, Frank, Gaensler, B., Hernquist, Lars, Mitchell, D., Morales, Miguel, Sethi, S., Subrahmanyan, R., Sadler, E., Arcus, Wayne, Barnes, David, Bernardi, G., Bunton, John, Cappallo, Roger, Crosse, B., Corey, Brian., Deshpande, Avinash, DeSouza, Ludi, Emrich, D., Goeke, Robert, Greenhill, L., Hazelton, Bryna, Herne, David, Kaplan, D., Kasper, Justin, Kincaid, Barton, Koenig, R., Kratzenberg, Eric, Lonsdale, Colin, Lynch, Mervyn, McWhirter, S., Morgan, Edward, Oberoi, Divya, Ord, Stephen, Pathikulangara, Joseph, Prabu, T., Remillard, Ron, Rogers, Alan, Roshi, Anish, Salah, J., Sault, R., Shankar, N Udaya, Srivani, K., Stevens, J., Tingay, Steven, Wayth, Randall, Waterson, Mark, Webster, Rachel, Whitney, Alan, Williams, A., Wyithe, J., Williams, C., Hewitt, J., Levine, A., de Oliveira-Costa, A., Bowman, Judd, Briggs, Frank, Gaensler, B., Hernquist, Lars, Mitchell, D., Morales, Miguel, Sethi, S., Subrahmanyan, R., Sadler, E., Arcus, Wayne, Barnes, David, Bernardi, G., Bunton, John, Cappallo, Roger, Crosse, B., Corey, Brian., Deshpande, Avinash, DeSouza, Ludi, Emrich, D., Goeke, Robert, Greenhill, L., Hazelton, Bryna, Herne, David, Kaplan, D., Kasper, Justin, Kincaid, Barton, Koenig, R., Kratzenberg, Eric, Lonsdale, Colin, Lynch, Mervyn, McWhirter, S., Morgan, Edward, Oberoi, Divya, Ord, Stephen, Pathikulangara, Joseph, Prabu, T., Remillard, Ron, Rogers, Alan, Roshi, Anish, Salah, J., Sault, R., Shankar, N Udaya, Srivani, K., Stevens, J., Tingay, Steven, Wayth, Randall, Waterson, Mark, Webster, Rachel, Whitney, Alan, Williams, A., and Wyithe, J.

Abstract

The Murchison Widefield Array (MWA) is a new low-frequency, wide-field-of-view radio interferometer under development at the Murchison Radio-astronomy Observatory in Western Australia. We have used a 32 element MWA prototype interferometer (MWA-32T) to observe two 50 degrees diameter fields in the southern sky, covering a total of similar to 2700 deg(2), in order to evaluate the performance of the MWA-32T, to develop techniques for epoch of reionization experiments, and to make measurements of astronomical foregrounds. We developed a calibration and imaging pipeline for the MWA-32T, and used it to produce similar to 15' angular resolution maps of the two fields in the 110-200 MHz band. We perform a blind source extraction using these confusion-limited images, and detect 655 sources at high significance with an additional 871 lower significance source candidates. We compare these sources with existing low-frequency radio surveys in order to assess the MWA-32T system performance, wide-field analysis algorithms, and catalog quality. Our source catalog is found to agree well with existing low-frequency surveys in these regions of the sky and with statistical distributions of point sources derived from Northern Hemisphere surveys; it represents one of the deepest surveys to date of this sky field in the 110-200 MHz band.

Published
2012

27. First Spectroscopic Imaging Observations of the Sun at Low Radio Frequencies with the Murchison Widefield Array Prototype

Author

Oberoi, D., Matthews, L., Cairns, I., Emrich, David, Lobzin, V., Lonsdale, C., Morgan, E., Prabu, T., Vedantham, H., Wayth, Randall, Williams, A., Williams, C., White, S., Allen, G., Arcus, Wayne, Barnes, D., Benkevitch, L., Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Burns, S., Cappallo, R., Clark, M., Corey, B., Dawson, M., DeBoer, D., De Gans, A., DeSouza, L., Derome, M., Edgar, R., Elton, T., Goeke, R., Gopalakrishna, M., Greenhill, L., Hazelton, B., Herne, David, Hewitt, J., Kamini, P., Kaplan, D., Kasper, J., Kennedy, R., Kincaid, B., Kocz, J., Koeing, R., Kowald, E., Lynch, Mervyn, Madhavi, S., McWhirter, S., Mitchell, D., Morales, M., Ng, A., Ord, Stephen, Pathikulangara, J., Rogers, A., Roshi, A., Salah, J., Sault, R., Schinckel, A., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Thakkar, D., Tingay, Steven, Tuthill, J., Vaccarella, A., Waterson, Mark, Webster, R., Whitney, A., Oberoi, D., Matthews, L., Cairns, I., Emrich, David, Lobzin, V., Lonsdale, C., Morgan, E., Prabu, T., Vedantham, H., Wayth, Randall, Williams, A., Williams, C., White, S., Allen, G., Arcus, Wayne, Barnes, D., Benkevitch, L., Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Burns, S., Cappallo, R., Clark, M., Corey, B., Dawson, M., DeBoer, D., De Gans, A., DeSouza, L., Derome, M., Edgar, R., Elton, T., Goeke, R., Gopalakrishna, M., Greenhill, L., Hazelton, B., Herne, David, Hewitt, J., Kamini, P., Kaplan, D., Kasper, J., Kennedy, R., Kincaid, B., Kocz, J., Koeing, R., Kowald, E., Lynch, Mervyn, Madhavi, S., McWhirter, S., Mitchell, D., Morales, M., Ng, A., Ord, Stephen, Pathikulangara, J., Rogers, A., Roshi, A., Salah, J., Sault, R., Schinckel, A., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Thakkar, D., Tingay, Steven, Tuthill, J., Vaccarella, A., Waterson, Mark, Webster, R., and Whitney, A.

Abstract

We present the first spectroscopic images of solar radio transients from the prototype for the Murchison Widefield Array, observed on 2010 March 27. Our observations span the instantaneous frequency band 170.9– 201.6 MHz. Though our observing period is characterized as a period of “low” to “medium” activity, one broadband emission feature and numerous short-lived, narrowband, non-thermal emission features are evident. Our data represent a significant advance in low radio frequency solar imaging, enabling us to follow the spatial, spectral, and temporal evolution of events simultaneously and in unprecedented detail. The rich variety of features seen here reaffirms the coronal diagnostic capability of low radio frequency emission and provides an early glimpse of the nature of radio observations that will become available as the next generation of low-frequency radio interferometers come online over the next few years.

Published
2011

28. Interferometric Imaging with the 32 Element Murchison Wide-Field Array

Author

Ord, S., Mitchell, D., Wayth, Randall, Greenhill, L., Bernadi, G., Gleadow, A., Edgar, R.G., Clarke, M.A., Allen, G., Arcus, Wayne, Benkevitch, L., Bowman, J.D., Briggs, F.H., Bunton, J.D., Burns, S., Cappallo, R.J., Coles, W.A., Corey, B.E., DeSouza, L., Doeleman, S.S., Derome, M., Deshpande, A., Emrich, D., Goeke, M.R., Gopalakrishna, M.R., Herne, David, Hewitt, J.N., Kamini, P.A., Kaplan, D.L., Kasper, J.C., Kincaid, B.B., Kocz, J., Kowald, E., Kratzenberg, E., Kumar, D., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Madhavi, S., Matejek, M., Morales, M., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Rogers, A., Roshi, A., Salah, J., Schinkel, A., Udaya, S.N., Srivani, K., Stevens, J., Tingay, Steven, Vaccarella, A., Waterson, Mark, Ord, S., Mitchell, D., Wayth, Randall, Greenhill, L., Bernadi, G., Gleadow, A., Edgar, R.G., Clarke, M.A., Allen, G., Arcus, Wayne, Benkevitch, L., Bowman, J.D., Briggs, F.H., Bunton, J.D., Burns, S., Cappallo, R.J., Coles, W.A., Corey, B.E., DeSouza, L., Doeleman, S.S., Derome, M., Deshpande, A., Emrich, D., Goeke, M.R., Gopalakrishna, M.R., Herne, David, Hewitt, J.N., Kamini, P.A., Kaplan, D.L., Kasper, J.C., Kincaid, B.B., Kocz, J., Kowald, E., Kratzenberg, E., Kumar, D., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Madhavi, S., Matejek, M., Morales, M., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Rogers, A., Roshi, A., Salah, J., Schinkel, A., Udaya, S.N., Srivani, K., Stevens, J., Tingay, Steven, Vaccarella, A., and Waterson, Mark

Abstract

The Murchison Wide-Field Array (MWA) is a low-frequency radio telescope, currently under construction, intended to search for the spectral signature of the epoch of reionization (EOR) and to probe the structure of the solar corona. Sited in western Australia, the full MWA will comprise 8192 dipoles grouped into 512 tiles and will be capable of imaging the sky south of 40° declination, from 80 MHz to 300 MHz with an instantaneous field of view that is tens of degrees wide and a resolution of a few arcminutes. A 32 station prototype of the MWA has been recently commissioned and a set of observations has been taken that exercise the whole acquisition and processing pipeline. We present Stokes I, Q, and U images from two ~4 hr integrations of a field 20° wide centered on Pictoris A. These images demonstrate the capacity and stability of a real-time calibration and imaging technique employing the weighted addition of warped snapshots to counter extreme wide-field imaging distortions.

Published
2010

29. The Murchison Widefield Array

Author

RFI2010, Mitchell, Daniel A., Greenhill, Lincoln J., Ord, Stephen M., Bernardi, Gianni, Wayth, Randall B., Edgar, Richard G., Clarke, Michael A., Dale, Kevin, Pfister, Hanspeter, Gleadow, Stewart J., Arcus, Wayne, Briggs, F.H., Benkevitch, L., Bowman, J.D., Bunton, J.D., Burns, S., Cappallo, R.J., Corey, B.E., de Oliveira-Costa, A., Desouza, L., Doeleman, S.S., Derome, M.F., Emrich, David, Glossop, Mark, Goeke, R., Gopala Krishna, M.R., Hazelton, B., Herne, David, Hewitt, J.N., Kamini, P.A., Kaplan, D.L., Kasper, J.C., Kincaid, B.B., Kocz, J., Kowald, E., Kratzenberg, E., Kumar, D., Lonsdale, C.J., Lynch, M.J., Madhavi, S., Matejek, M., McWhirter, S.R., Morales, M.F., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Rogers, A., Salah, J.E., Sault, R.J., Udaya Shankar, N., Srivani, K.S., Stevens, J., Tingay, Steven, Vaccarella, A., Waterson, Mark, Webster, R.L., Whitney, A.R., Williams, A., Williams, C., RFI2010, Mitchell, Daniel A., Greenhill, Lincoln J., Ord, Stephen M., Bernardi, Gianni, Wayth, Randall B., Edgar, Richard G., Clarke, Michael A., Dale, Kevin, Pfister, Hanspeter, Gleadow, Stewart J., Arcus, Wayne, Briggs, F.H., Benkevitch, L., Bowman, J.D., Bunton, J.D., Burns, S., Cappallo, R.J., Corey, B.E., de Oliveira-Costa, A., Desouza, L., Doeleman, S.S., Derome, M.F., Emrich, David, Glossop, Mark, Goeke, R., Gopala Krishna, M.R., Hazelton, B., Herne, David, Hewitt, J.N., Kamini, P.A., Kaplan, D.L., Kasper, J.C., Kincaid, B.B., Kocz, J., Kowald, E., Kratzenberg, E., Kumar, D., Lonsdale, C.J., Lynch, M.J., Madhavi, S., Matejek, M., McWhirter, S.R., Morales, M.F., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Rogers, A., Salah, J.E., Sault, R.J., Udaya Shankar, N., Srivani, K.S., Stevens, J., Tingay, Steven, Vaccarella, A., Waterson, Mark, Webster, R.L., Whitney, A.R., Williams, A., and Williams, C.

Published
2010

30. The Murchison Widefield Array: Design Overview

Author

Lonsdale, Colin J, Cappallo, Roger C, Morales, Miguel, Briggs, Franklin, Benkevitch, Leonid, Bowman, Judd D, Bunton, John D., Burns, Steven, Corey, Brian E, Desouza, Ludi, Doeleman, Sheperd S, Derome, Mark, Deshpande, Avinash, Gopala, Modavanatt Ramakrishna, Greenhill, Lincoln, Herne, David, Hewitt, Jacqueline N, Kamini, P A, Kasper, Justin C, Kincaid, Barton B, Kocz, J., Kowald, Errol, Kratzenberg, Eric, Kumar, Deepak, Lynch, Mervyn J, Madhavi, S, Matejek, Michael, Mitchell, Daniel A, Morgan, Edward, Oberoi, Divya, Ord, Steve, Pathikulangara, Joseph, Prabu, T, Rogers, Alan, Roshi, Anish, Salah, Joseph E, Sault, Robert J, Shankar, N.Udaya, Srivani, K. S., Stevens, Jamie, Tingay, Steven, Vaccarella, Annino, Waterson, Mark, Wayth, Randall B, Webster, Rachel L, Whitney, Alan, Williams, Andrew, Williams, Christopher, Lonsdale, Colin J, Cappallo, Roger C, Morales, Miguel, Briggs, Franklin, Benkevitch, Leonid, Bowman, Judd D, Bunton, John D., Burns, Steven, Corey, Brian E, Desouza, Ludi, Doeleman, Sheperd S, Derome, Mark, Deshpande, Avinash, Gopala, Modavanatt Ramakrishna, Greenhill, Lincoln, Herne, David, Hewitt, Jacqueline N, Kamini, P A, Kasper, Justin C, Kincaid, Barton B, Kocz, J., Kowald, Errol, Kratzenberg, Eric, Kumar, Deepak, Lynch, Mervyn J, Madhavi, S, Matejek, Michael, Mitchell, Daniel A, Morgan, Edward, Oberoi, Divya, Ord, Steve, Pathikulangara, Joseph, Prabu, T, Rogers, Alan, Roshi, Anish, Salah, Joseph E, Sault, Robert J, Shankar, N.Udaya, Srivani, K. S., Stevens, Jamie, Tingay, Steven, Vaccarella, Annino, Waterson, Mark, Wayth, Randall B, Webster, Rachel L, Whitney, Alan, Williams, Andrew, and Williams, Christopher

Abstract

The Murchison Widefield Array is a dipole-based aperture array synthesis telescope designed to operate in the 80300 MHz frequency range. It is capable of a wide range of science investigations but is initially focused on three key science projects: detection and characterization of three-dimensional brightness temperature fluctuations in the 21 cm line of neutral hydrogen during the epoch of reionization (EoR) at redshifts from six to ten; solar imaging and remote sensing of the inner heliosphere via propagation effects on signals from distant background sources; and high-sensitivity exploration of the variable radio sky. The array design features 8192 dual-polarization broadband active dipoles, arranged into 512 tiles comprising 16 dipoles each. The tiles are quasi-randomly distributed over an aperture 1.5 km in diameter, with a small number of outliers extending to 3 km. All tiletile baselines are correlated in custom field-programmable gate array based hardware, yielding a Nyquist-sampled instantaneous monochromatic uv coverage and unprecedented point spread function quality. The correlated data are calibrated in real time using novel position-dependent self-calibration algorithms. The array is located in the Murchison region of outback Western Australia. This region is characterized by extremely low population density and a superbly radio-quiet environment, allowing full exploitation of the instrumental capabilities.

Published
2009

31. The Murchison Widefield Array: Design Overview

Author

Lonsdale, Colin, Cappallo, Roger, Morales, Miguel, Briggs, Frank, Benkevitch, Leonid, Bowman, Judd, Bunton, John, Burns, Steven, Corey, Brian, DeSouza, Ludi, Doeleman, Sheperd, Derome, Mark, Deshpande, Avinash, Gopala, Modavanatt, Greenhill, Lincoln, Herne, David, Hewitt, Jacqueline, Kamini, P., Kasper, Justin, Kincaid, Barton, Kocz, Jonathon, Kowald, Errol, Kratzenberg, Eric, Kumar, Deepak, Lynch, Mervyn, Madhavi, S., Matejek, Michael, Mitchell, Daniel, Morgan, Edward, Oberoi, Divya, Ord, Steven, Pathikulangara, Joseph, Prabu, T., Rogers, Alan, Roshi, Anish, Saleh, Joseph, Sault, Robert, Shankar, N. Udaya, Srivani, K., Stevens, Jamie, Tingay, Steven, Vaccarella, Annino, Waterson, Mark, Wayth, Randall, Webster, Rachel, Whitney, Alan, Williams, Andrew, Williams, Christopher, Lonsdale, Colin, Cappallo, Roger, Morales, Miguel, Briggs, Frank, Benkevitch, Leonid, Bowman, Judd, Bunton, John, Burns, Steven, Corey, Brian, DeSouza, Ludi, Doeleman, Sheperd, Derome, Mark, Deshpande, Avinash, Gopala, Modavanatt, Greenhill, Lincoln, Herne, David, Hewitt, Jacqueline, Kamini, P., Kasper, Justin, Kincaid, Barton, Kocz, Jonathon, Kowald, Errol, Kratzenberg, Eric, Kumar, Deepak, Lynch, Mervyn, Madhavi, S., Matejek, Michael, Mitchell, Daniel, Morgan, Edward, Oberoi, Divya, Ord, Steven, Pathikulangara, Joseph, Prabu, T., Rogers, Alan, Roshi, Anish, Saleh, Joseph, Sault, Robert, Shankar, N. Udaya, Srivani, K., Stevens, Jamie, Tingay, Steven, Vaccarella, Annino, Waterson, Mark, Wayth, Randall, Webster, Rachel, Whitney, Alan, Williams, Andrew, and Williams, Christopher

Abstract

The Murchison Widefield Array is a dipole-based aperture array synthesis telescope designed to operate in the 80-300 MHz frequency range. It is capable of a wide range of science investigations but is initially focused on three key science projects: detection and characterization of three dimensional brightness temperature fluctuations in the 21 cmline of neutral hydrogen during the epoch of reionization (EoR) at red shifts from six to ten; solar imaging and remote sensing of the inner heliosphere via propagation effects on signals from distant background sources; and high-sensitivity exploration ofthe variable radio sky. The array design features 8192 dualpolarization broadband active dipoles, arranged into 512 Btiles, comprising 16 dipoles each. The tiles are quasi-randomly distributed over an aperture 1.5 km in diameter, with a small number of outliers extending to 3 km. All tile-tile baselines are correlated in custom field-programmable gate array based hardware, yielding a Nyquist-sampled instantaneous monochromaticuv coverage and unprecedented point spread function quality. The correlated data are calibrated in real time using novel position-dependent self-calibration algorithms. The array is located in the Murchison region of outback Western Australia. This region is characterized by extremely low population density and a superbly radio-quiet environment, allowing full exploitation of the instrumental capabilities.

Published
2009

32. A STUDY OF FUNDAMENTAL LIMITATIONS TO STATISTICAL DETECTION OF REDSHIFTED H I FROM THE EPOCH OF REIONIZATION

Author

Thyagarajan, Nithyanandan, primary, Udaya Shankar, N., additional, Subrahmanyan, Ravi, additional, Arcus, Wayne, additional, Bernardi, Gianni, additional, Bowman, Judd D., additional, Briggs, Frank, additional, Bunton, John D., additional, Cappallo, Roger J., additional, Corey, Brian E., additional, deSouza, Ludi, additional, Emrich, David, additional, Gaensler, Bryan M., additional, Goeke, Robert F., additional, Greenhill, Lincoln J., additional, Hazelton, Bryna J., additional, Herne, David, additional, Hewitt, Jacqueline N., additional, Johnston-Hollitt, Melanie, additional, Kaplan, David L., additional, Kasper, Justin C., additional, Kincaid, Barton B., additional, Koenig, Ronald, additional, Kratzenberg, Eric, additional, Lonsdale, Colin J., additional, Lynch, Mervyn J., additional, McWhirter, S. Russell, additional, Mitchell, Daniel A., additional, Morales, Miguel F., additional, Morgan, Edward H., additional, Oberoi, Divya, additional, Ord, Stephen M., additional, Pathikulangara, Joseph, additional, Remillard, Ronald A., additional, Rogers, Alan E. E., additional, Roshi, D. Anish, additional, Salah, Joseph E., additional, Sault, Robert J., additional, Srivani, K. S., additional, Stevens, Jamie B., additional, Thiagaraj, Prabu, additional, Tingay, Steven J., additional, Wayth, Randall B., additional, Waterson, Mark, additional, Webster, Rachel L., additional, Whitney, Alan R., additional, Williams, Andrew J., additional, Williams, Christopher L., additional, and Wyithe, J. Stuart B., additional

Published
2013
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33. Science with the Murchison Widefield Array

Author

Bowman, Judd D., primary, Cairns, Iver, additional, Kaplan, David L., additional, Murphy, Tara, additional, Oberoi, Divya, additional, Staveley-Smith, Lister, additional, Arcus, Wayne, additional, Barnes, David G., additional, Bernardi, Gianni, additional, Briggs, Frank H., additional, Brown, Shea, additional, Bunton, John D., additional, Burgasser, Adam J., additional, Cappallo, Roger J., additional, Chatterjee, Shami, additional, Corey, Brian E., additional, Coster, Anthea, additional, Deshpande, Avinash, additional, deSouza, Ludi, additional, Emrich, David, additional, Erickson, Philip, additional, Goeke, Robert F., additional, Gaensler, B. M., additional, Greenhill, Lincoln J., additional, Harvey-Smith, Lisa, additional, Hazelton, Bryna J., additional, Herne, David, additional, Hewitt, Jacqueline N., additional, Johnston-Hollitt, Melanie, additional, Kasper, Justin C., additional, Kincaid, Barton B., additional, Koenig, Ronald, additional, Kratzenberg, Eric, additional, Lonsdale, Colin J., additional, Lynch, Mervyn J., additional, Matthews, Lynn D., additional, McWhirter, S. Russell, additional, Mitchell, Daniel A., additional, Morales, Miguel F., additional, Morgan, Edward H., additional, Ord, Stephen M., additional, Pathikulangara, Joseph, additional, Prabu, Thiagaraj, additional, Remillard, Ronald A., additional, Robishaw, Timothy, additional, Rogers, Alan E. E., additional, Roshi, Anish A., additional, Salah, Joseph E., additional, Sault, Robert J., additional, Shankar, N. Udaya, additional, Srivani, K. S., additional, Stevens, Jamie B., additional, Subrahmanyan, Ravi, additional, Tingay, Steven J., additional, Wayth, Randall B., additional, Waterson, Mark, additional, Webster, Rachel L., additional, Whitney, Alan R., additional, Williams, Andrew J., additional, Williams, Christopher L., additional, and Wyithe, J. Stuart B., additional

Published
2013
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34. Field Deployment of Prototype Antenna Tiles for the Mileura Widefield Array Low Frequency Demonstrator

Author

Bowman, Judd D, Barnes, David G, Briggs, Franklin, Corey, Brian E, Lynch, Mervyn J, Bhat, N D Ramesh, Cappallo, Roger C, Doeleman, Sheperd S, Fanous, Brian J, Herne, David, Hewitt, Jacqueline N, Johnston, Chris, Kasper, Justin C, Kocz, J., Kratzenberg, Eric, Lonsdale, Colin J, Morales, Miguel, Oberoi, Divya, Salah, Joseph E, Stansby, Bruce, Stevens, Jamie, Torr, Glen, Wayth, Randall, Webster, Rachel L, Wyithe, J Stuart B, Bowman, Judd D, Barnes, David G, Briggs, Franklin, Corey, Brian E, Lynch, Mervyn J, Bhat, N D Ramesh, Cappallo, Roger C, Doeleman, Sheperd S, Fanous, Brian J, Herne, David, Hewitt, Jacqueline N, Johnston, Chris, Kasper, Justin C, Kocz, J., Kratzenberg, Eric, Lonsdale, Colin J, Morales, Miguel, Oberoi, Divya, Salah, Joseph E, Stansby, Bruce, Stevens, Jamie, Torr, Glen, Wayth, Randall, Webster, Rachel L, and Wyithe, J Stuart B

Abstract

Experiments were performed with prototype antenna tiles for the Mileura Widefield Array Low Frequency Demonstrator (MWA LFD) to better understand the wide-field, wide-band properties of their design and to characterize the radio-frequency interference (RFI) between 80 and 300 MHz at the site in Western Australia. Observations acquired during the 6 month deployment confirmed the predicted sensitivity of the antennas, sky-noise-dominated system temperatures, and phase-coherent interferometric measurements. The radio spectrum is remarkably free of strong terrestrial signals, with the exception of two narrow frequency bands allocated to satellite downlinks, and rare bursts due to ground-based transmissions being scattered from aircraft and meteor trails. Results indicate the potential of the MWA LFD to make significant achievements in its three key science objectives: epoch of reionization science, heliospheric science, and radio transient detection.

Published
2007

36. LOW-FREQUENCY IMAGING OF FIELDS AT HIGH GALACTIC LATITUDE WITH THE MURCHISON WIDEFIELD ARRAY 32 ELEMENT PROTOTYPE

Author

Williams, Christopher L., primary, Hewitt, Jacqueline N., additional, Levine, Alan M., additional, de Oliveira-Costa, Angelica, additional, Bowman, Judd D., additional, Briggs, Frank H., additional, Gaensler, B. M., additional, Hernquist, Lars L., additional, Mitchell, Daniel A., additional, Morales, Miguel F., additional, Sethi, Shiv K., additional, Subrahmanyan, Ravi, additional, Sadler, Elaine M., additional, Arcus, Wayne, additional, Barnes, David G., additional, Bernardi, Gianni, additional, Bunton, John D., additional, Cappallo, Roger C., additional, Crosse, Brian W., additional, Corey, Brian E., additional, Deshpande, Avinash, additional, deSouza, Ludi, additional, Emrich, David, additional, Goeke, Robert F., additional, Greenhill, Lincoln J., additional, Hazelton, Bryna J., additional, Herne, David, additional, Kaplan, David L., additional, Kasper, Justin C., additional, Kincaid, Barton B., additional, Koenig, Ronald, additional, Kratzenberg, Eric, additional, Lonsdale, Colin J., additional, Lynch, Mervyn J., additional, McWhirter, S. Russell, additional, Morgan, Edward H., additional, Oberoi, Divya, additional, Ord, Stephen M., additional, Pathikulangara, Joseph, additional, Prabu, Thiagaraj, additional, Remillard, Ronald A., additional, Rogers, Alan E. E., additional, Roshi, D. Anish, additional, Salah, Joseph E., additional, Sault, Robert J., additional, Shankar, N. Udaya, additional, Srivani, K. S., additional, Stevens, Jamie B., additional, Tingay, Steven J., additional, Wayth, Randall B., additional, Waterson, Mark, additional, Webster, Rachel L., additional, Whitney, Alan R., additional, Williams, Andrew J., additional, and Wyithe, J. Stuart B., additional

Published
2012
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37. FIRST SPECTROSCOPIC IMAGING OBSERVATIONS OF THE SUN AT LOW RADIO FREQUENCIES WITH THE MURCHISON WIDEFIELD ARRAY PROTOTYPE

Author

Oberoi, Divya, primary, Matthews, Lynn D., additional, Cairns, Iver H., additional, Emrich, David, additional, Lobzin, Vasili, additional, Lonsdale, Colin J., additional, Morgan, Edward H., additional, Prabu, T., additional, Vedantham, Harish, additional, Wayth, Randall B., additional, Williams, Andrew, additional, Williams, Christopher, additional, White, Stephen M., additional, Allen, G., additional, Arcus, Wayne, additional, Barnes, David, additional, Benkevitch, Leonid, additional, Bernardi, Gianni, additional, Bowman, Judd D., additional, Briggs, Frank H., additional, Bunton, John D., additional, Burns, Steve, additional, Cappallo, Roger C., additional, Clark, M. A., additional, Corey, Brian E., additional, Dawson, M., additional, DeBoer, David, additional, De Gans, A., additional, deSouza, Ludi, additional, Derome, Mark, additional, Edgar, R. G., additional, Elton, T., additional, Goeke, Robert, additional, Gopalakrishna, M. R., additional, Greenhill, Lincoln J., additional, Hazelton, Bryna, additional, Herne, David, additional, Hewitt, Jacqueline N., additional, Kamini, P. A., additional, Kaplan, David L., additional, Kasper, Justin C., additional, Kennedy, Rachel, additional, Kincaid, Barton B., additional, Kocz, Jonathan, additional, Koeing, R., additional, Kowald, Errol, additional, Lynch, Mervyn J., additional, Madhavi, S., additional, McWhirter, Stephen R., additional, Mitchell, Daniel A., additional, Morales, Miguel F., additional, Ng, A., additional, Ord, Stephen M., additional, Pathikulangara, Joseph, additional, Rogers, Alan E. E., additional, Roshi, Anish, additional, Salah, Joseph E., additional, Sault, Robert J., additional, Schinckel, Antony, additional, Udaya Shankar, N., additional, Srivani, K. S., additional, Stevens, Jamie, additional, Subrahmanyan, Ravi, additional, Thakkar, D., additional, Tingay, Steven J., additional, Tuthill, J., additional, Vaccarella, Annino, additional, Waterson, Mark, additional, Webster, Rachel L., additional, and Whitney, Alan R., additional

Published
2011
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38. THE PRECISION ARRAY FOR PROBING THE EPOCH OF RE-IONIZATION: EIGHT STATION RESULTS

Author

Parsons, Aaron R., primary, Backer, Donald C., additional, Foster, Griffin S., additional, Wright, Melvyn C. H., additional, Bradley, Richard F., additional, Gugliucci, Nicole E., additional, Parashare, Chaitali R., additional, Benoit, Erin E., additional, Aguirre, James E., additional, Jacobs, Daniel C., additional, Carilli, Chris L., additional, Herne, David, additional, Lynch, Mervyn J., additional, Manley, Jason R., additional, and Werthimer, Daniel J., additional

Published
2010
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40. Detection of Crab Giant Pulses Using the Mileura Widefield Array Low Frequency Demonstrator Field Prototype System

Author

Bhat, N. D. Ramesh, primary, Wayth, Randall B., additional, Knight, Haydon S., additional, Bowman, Judd D., additional, Oberoi, Divya, additional, Barnes, David G., additional, Briggs, Frank H., additional, Cappallo, Roger J., additional, Herne, David, additional, Kocz, Jonathon, additional, Lonsdale, Colin J., additional, Lynch, Mervyn J., additional, Stansby, Bruce, additional, Stevens, Jamie, additional, Torr, Glen, additional, Webster, Rachel L., additional, and Wyithe, J. Stuart B., additional

Published
2007
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41. Field Deployment of Prototype Antenna Tiles for the Mileura Widefield Array Low Frequency Demonstrator

Author

Bowman, Judd D., primary, Barnes, David G., additional, Briggs, Frank H., additional, Corey, Brian E., additional, Lynch, Merv J., additional, Ramesh Bhat, N. D., additional, Cappallo, Roger J., additional, Doeleman, Sheperd S., additional, Fanous, Brian J., additional, Herne, David, additional, Hewitt, Jacqueline N., additional, Johnston, Chris, additional, Kasper, Justin C., additional, Kocz, Jonathon, additional, Kratzenberg, Eric, additional, Lonsdale, Colin J., additional, Morales, Miguel F., additional, Oberoi, Divya, additional, Salah, Joseph E., additional, Stansby, Bruce, additional, Stevens, Jamie, additional, Torr, Glen, additional, Wayth, Randall, additional, Webster, Rachel L., additional, and Wyithe, J. Stuart B., additional

Published
2007
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