Serendipitous discovery of a dying Giant Radio Galaxy associated with NGC 1534, using the Murchison Widefield Array

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.Recent observations with the Murchison Widefield Array at 185~MHz have serendipitously unveiled a heretofore unknown giant and relatively nearby ($z = 0.0178$) radio galaxy associated with NGC\,1534. The diffuse emission presented here is the first indication that NGC\,1534 is one of a rare class of objects (along with NGC\,5128 and NGC\,612) in which a galaxy with a prominent dust lane hosts radio emission on scales of $\sim$700\,kpc. We present details of the radio emission along with a detailed comparison with other radio galaxies with disks. NGC1534 is the lowest surface brightness radio galaxy known with an estimated scaled 1.4-GHz surface brightness of just 0.2\,mJy\,arcmin$^{-2}$. The radio lobes have one of the steepest spectral indices yet observed: $\alpha=-2.1\pm0.1$, and the core to lobe luminosity ratio is $Peer reviewe

Study of redshifted H I from the epoch of reionization with drift scan

The detection of the Epoch of Reionization (EoR) in the redshifted 21-cm line is a challenging task. Here we formulate the detection of the EoR signal using the drift scan strategy. This method potentially has better instrumental stability as compared to the case where a single patch of sky is tracked. We demonstrate that the correlation time between measured visibilities could extend up to 1-2 hr for an interferometer array such as the Murchison Widefield Array (MWA), which has a wide primary beam. We estimate the EoR power based on cross-correlation of visibilities across time and show that the drift scan strategy is capable of the detection of the EoR signal with comparable/better signal-to-noise as compared to the tracking case. We also estimate the visibility correlation for a set of bright point sources and argue that the statistical inhomogeneity of bright point sources might allow their separation from the EoR signal

The Murchison Widefield Array: The Square Kilometre Array Precursor at Low Radio Frequencies

The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80–300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3-km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper, the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised

Remaking the self in John Dunton’s The Life and Errors of John Dunton (1705)

© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. John Dunton (1659–1732) is a bookseller and writer best known today as a tireless self-promoter whose I-centred and experimental work contributed to the development of the novel and autobiography in the eighteenth century. This article is the first full-length study of his own autobiographical record, The Life and Errors of John Dunton (1705). Dunton the showman is in plentiful evidence in this text, but he also presents another, more sober and serious-minded version of the self by following accounts of earlier stages of his life with their reformed versions. His coupling of religious-led self-examination with a commitment to literary novelty makes The Life a most unusual form of spiritual autobiography in its early stages. Yet The Life is a composite text in an even more obvious sense than this. For around half-way through the text Dunton abandons his close focus on the self for hundreds of cursory character sketches of his contemporaries, and in doing so swaps spiritual considerations for indirect comments on his own social activities and commercial concerns. This article studies these two main, ostensibly opposed, sections of The Life–its autobiographical and biographical material–and suggests points of contact between them

Remembering Sir Francis Drake: Travel, commemoration and national identity in the work of Henry Robarts

© Manchester University Press. Henry Robarts is a little-known writer whose work includes prose romances, records of state entertainments, and commendatory pamphlets on travel. This article pays particular attention to his celebrations of Sir Francis Drake, which form part of a sub-genre of writing on travel and which provide insights into how voyages of discovery figured in the late-sixteenth-century popular imagination. It considers how Robarts theorises the act of commemoration in these and other texts, and looks at the crucial role he imagines both it and travel to play in shaping England's national identity

Classical and contemporary Italy in Roger Ascham's The Scholemaster (1570)

This article seeks to show that a consideration of the use of Italy in Roger Ascham's The Scholemaster (1570) is illuminated by a study of the structural progression of book 1 (from educational methodologies, to a declamation against courtly vices, to an objection to travel to Italy). Specifically, it argues that the final section on Italy is conceived as a threat to those pedagogical and moral ideals of order, discipline and discrimination outlined in earlier sections; and that this closing statement forcibly demonstrates, and gives particular expression to, Ascham's humanist commitment to maintaining such well-schooled qualities against pernicious contemporary influences. Attention directed to the range of concerns addressed in the text also points to Ascham's conflicted use of Italy. For whilst his humanist educative project accompanies a concern to privilege the moral and cultural influences of classical over contemporary Italy, his national project of literary acculturation (witnessed in such things as his objection to courtly versifying) involves an attempt to conflate, rather than to distinguish, specific Italian identities

Discovery of a steep-spectrum low-luminosity pulsar with the Murchison Widefield Array

We report the discovery of the first new pulsar with the Murchison Widefield Array (MWA), PSR J0036−1033, a long-period (0.9 s) nonrecycled pulsar with a dispersion measure (DM) of 23.1 pc cm−3 . It was found after processing only a small fraction (∼1%) of data from an ongoing all-sky pulsar survey. Follow-up observations have been made with the MWA, the upgraded Giant Metrewave Radio Telescope (uGMRT), and the Parkes 64 m telescopes, spanning a frequency range from ∼150 MHz to 4 GHz. The pulsar is faint, with an estimated flux density (S) of ∼1 mJy at 400 MHz and a spectrum S(v) α v - S 2.0±0.2, where ν is frequency. The DM-derived distance implies that it is also a low-luminosity source (∼0.1 mJy kpc2 at 1400 MHz). The analysis of archival MWA observations reveals that the pulsar’s mean flux density varies by up to a factor of ∼5–6 on timescales of several weeks to months. By combining MWA and uGMRT data, the pulsar position was determined to arcsecond precision. We also report on polarization properties detected in the MWA and Parkes bands. The pulsar’s nondetection in previous pulsar and continuum imaging surveys, the observed high variability, and its detection in a small fraction of the survey data searched to date, all hint at a larger population of pulsars that await discovery in the southern hemisphere, with the MWA and the future low-frequency Square Kilometre Array