Search

Your search keyword '"Hotan, AW"' showing total 7 results
Start Over Author "Hotan, AW"
7 results on '"Hotan, AW"'

1. The Rapid ASKAP Continuum Survey I: Design and first results

Author

McConnell, D, Hale, CL, Lenc, E, Banfield, JK, Heald, G, Hotan, AW, Leung, JK, Moss, VA, Murphy, T, O'Brien, A, Pritchard, J, Raja, W, Sadler, EM, Stewart, A, Thomson, AJM, Whiting, M, Allison, JR, Amy, SW, Anderson, C, Ball, L, Bannister, KW, Bell, M, Bock, DCJ, Bolton, R, Bunton, JD, Chippendale, AP, Collier, JD, Cooray, FR, Cornwell, TJ, Diamond, PJ, Edwards, PG, Gupta, N, Hayman, DB, Heywood, I, Jackson, CA, Koribalski, BS, Lee-Waddell, K, McClure-Griffiths, NM, Ng, A, Norris, RP, Phillips, C, Reynolds, JE, Roxby, DN, Schinckel, AET, Shields, M, Tremblay, C, Tzioumis, A, Voronkov, MA, Westmeier, T, McConnell, D, Hale, CL, Lenc, E, Banfield, JK, Heald, G, Hotan, AW, Leung, JK, Moss, VA, Murphy, T, O'Brien, A, Pritchard, J, Raja, W, Sadler, EM, Stewart, A, Thomson, AJM, Whiting, M, Allison, JR, Amy, SW, Anderson, C, Ball, L, Bannister, KW, Bell, M, Bock, DCJ, Bolton, R, Bunton, JD, Chippendale, AP, Collier, JD, Cooray, FR, Cornwell, TJ, Diamond, PJ, Edwards, PG, Gupta, N, Hayman, DB, Heywood, I, Jackson, CA, Koribalski, BS, Lee-Waddell, K, McClure-Griffiths, NM, Ng, A, Norris, RP, Phillips, C, Reynolds, JE, Roxby, DN, Schinckel, AET, Shields, M, Tremblay, C, Tzioumis, A, Voronkov, MA, and Westmeier, T

Abstract

© The Author(s), 2020. Published by Cambridge University Press on behalf of the Astronomical Society of Australia. The Rapid ASKAP Continuum Survey (RACS) is the first large-area survey to be conducted with the full 36-antenna Australian Square Kilometre Array Pathfinder (ASKAP) telescope. RACS will provide a shallow model of the ASKAP sky that will aid the calibration of future deep ASKAP surveys. RACS will cover the whole sky visible from the ASKAP site in Western Australia and will cover the full ASKAP band of 700-1800 MHz. The RACS images are generally deeper than the existing NRAO VLA Sky Survey and Sydney University Molonglo Sky Survey radio surveys and have better spatial resolution. All RACS survey products will be public, including radio images (with $\sim$ 15 arcsec resolution) and catalogues of about three million source components with spectral index and polarisation information. In this paper, we present a description of the RACS survey and the first data release of 903 images covering the sky south of declination $+41^\circ$ made over a 288-MHz band centred at 887.5 MHz.

Published
2020

2. The Detection of an Extremely Bright Fast Radio Burst in a Phased Array Feed Survey

Author

Bannister, KW, Shannon, RM, Macquart, JP, Flynn, C, Edwards, PG, O'Neill, M, Osłowski, S, Bailes, M, Zackay, B, Clarke, N, D'Addario, LR, Dodson, R, Hall, PJ, Jameson, A, Jones, D, Navarro, R, Trinh, JT, Allison, J, Anderson, CS, Bell, M, Chippendale, AP, Collier, JD, Heald, G, Heywood, I, Hotan, AW, Lee-Waddell, K, Madrid, JP, Marvil, J, McConnell, D, Popping, A, Voronkov, MA, Whiting, MT, Allen, GR, Bock, DCJ, Brodrick, DP, Cooray, F, Deboer, DR, Diamond, PJ, Ekers, R, Gough, RG, Hampson, GA, Harvey-Smith, L, Hay, SG, Hayman, DB, Jackson, CA, Johnston, S, Koribalski, BS, McClure-Griffiths, NM, Mirtschin, P, Ng, A, Norris, RP, Pearce, SE, Phillips, CJ, Roxby, DN, Troup, ER, Westmeier, T, Bannister, KW, Shannon, RM, Macquart, JP, Flynn, C, Edwards, PG, O'Neill, M, Osłowski, S, Bailes, M, Zackay, B, Clarke, N, D'Addario, LR, Dodson, R, Hall, PJ, Jameson, A, Jones, D, Navarro, R, Trinh, JT, Allison, J, Anderson, CS, Bell, M, Chippendale, AP, Collier, JD, Heald, G, Heywood, I, Hotan, AW, Lee-Waddell, K, Madrid, JP, Marvil, J, McConnell, D, Popping, A, Voronkov, MA, Whiting, MT, Allen, GR, Bock, DCJ, Brodrick, DP, Cooray, F, Deboer, DR, Diamond, PJ, Ekers, R, Gough, RG, Hampson, GA, Harvey-Smith, L, Hay, SG, Hayman, DB, Jackson, CA, Johnston, S, Koribalski, BS, McClure-Griffiths, NM, Mirtschin, P, Ng, A, Norris, RP, Pearce, SE, Phillips, CJ, Roxby, DN, Troup, ER, and Westmeier, T

Abstract

© 2017. The American Astronomical Society. All rights reserved. We report the detection of an ultra-bright fast radio burst (FRB) from a modest, 3.4-day pilot survey with the Australian Square Kilometre Array Pathfinder. The survey was conducted in a wide-field fly's-eye configuration using the phased-array-feed technology deployed on the array to instantaneously observe an effective area of 160 deg2, and achieve an exposure totaling 13200 deg2 hr . We constrain the position of FRB 170107 to a region in size (90% containment) and its fluence to be 58 ±6 Jy ms. The spectrum of the burst shows a sharp cutoff above 1400 MHz, which could be due to either scintillation or an intrinsic feature of the burst. This confirms the existence of an ultra-bright (∼ Jy ms) population of FRBs.

Published
2017

3. Discovery of HI gas in a young radio galaxy at z = 0.44 using the Australian square kilometre array pathfinder

Author

Allison, JR, Sadler, EM, Moss, VA, Whiting, MT, Hunstead, RW, Pracy, MB, Curran, SJ, Croom, SM, Glowacki, M, Morganti, R, Shabala, SS, Zwaan, MA, Allen, G, Amy, SW, Axtens, P, Ball, L, Bannister, KW, Barker, S, Bell, ME, Bock, DCJ, Bolton, R, Bowen, M, Boyle, B, Braun, R, Broadhurst, S, Brodrick, D, Brothers, M, Brown, A, Bunton, JD, Cantrall, C, Chapman, J, Cheng, W, Chippendale, AP, Chung, Y, Cooray, F, Cornwell, T, DeBoer, D, Diamond, P, Edwards, PG, Ekers, R, Feain, I, Ferris, RH, Forsyth, R, Gough, R, Grancea, A, Gupta, N, Guzman, JC, Hampson, G, Harvey-Smith, L, Haskins, C, Hay, S, Hayman, DB, Heywood, I, Hotan, AW, Hoyle, S, Humphreys, B, Indermuehle, BT, Jacka, C, Jackson, C, Jackson, S, Jeganathan, K, Johnston, S, Joseph, J, Kendall, R, Kesteven, M, Kiraly, D, Koribalski, SB, Leach, M, Lenc, E, Lensson, E, Mackay, S, Macleod, A, Marquarding, M, Marvil, J, McClure-Griffiths, N, McConnell, D, Mirtschin, P, Norris, PR, Neuhold, S, Ng, A, O'Sullivan, J, Pathikulangara, J, Pearce, S, Phillips, C, Popping, A, Qiao, YR, Reynolds, EJ, Roberts, P, Sault, JR, Schinckel, A, Serra, P, Shaw, R, Shields, M, Shimwell, T, Storey, M, Sweetnam, T, Troup, E, Turner, B, Tuthill, J, and Tzioumis, A

Subjects
Astronomy & Astrophysics
Abstract

© 2015 The Authors. We report the discovery of a new 21-cm HI absorption system using commissioning data from the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP). Using the 711.5-1015.5 MHz band of ASKAP we were able to conduct a blind search for the 21-cm line in a continuous redshift range between z = 0.4 and 1.0, which has, until now, remained largely unexplored. The absorption line is detected at z = 0.44 towards the GHz-peaked spectrum radio source PKS B1740-517 and demonstrates ASKAP's excellent capability for performing a future wide-field survey for HI absorption at these redshifts. Optical spectroscopy and imaging using the Gemini-South telescope indicates that the HI gas is intrinsic to the host galaxy of the radio source. The narrow [OIII] emission lines show clear double-peaked structure, indicating either large-scale outflow or rotation of the ionized gas. Archival data from the XMM-Newton satellite exhibit an absorbed X-ray spectrum that is consistent with a high column density obscuring medium around the active galactic nucleus. The HI absorption profile is complex, with four distinct components ranging in width from 5 to 300 km s-1 and fractional depths from 0.2 to 20 per cent. In addition to systemic HI gas, in a circumnuclear disc or ring structure aligned with the radio jet, we find evidence for a possible broad outflow of neutral gas moving at a radial velocity of v ~ 300 km s-1. We infer that the expanding young radio source (tage ≈ 2500 yr) is cocooned within a dense medium and may be driving circumnuclear neutral gas in an outflow of ~1 M o˙ yr-1.

Published
2015

4. A pilot ASKAP survey of radio transient events in the region around the intermittent pulsar PSR J1107-5907

Author

Hobbs, G, Heywood, I, Bell, ME, Kerr, M, Rowlinson, A, Johnston, S, Shannon, RM, Voronkov, MA, Ward, C, Banyer, J, Hancock, PJ, Murphy, T, Allison, JR, Amy, SW, Ball, L, Bannister, K, Bock, DCJ, Brodrick, D, Brothers, M, Brown, AJ, Bunton, JD, Chapman, J, Chippendale, AP, Chung, Y, DeBoer, D, Diamond, P, Edwards, PG, Ekers, R, Ferris, RH, Forsyth, R, Gough, R, Grancea, A, Gupta, N, Harvey-Smith, L, Hay, S, Hayman, DB, Hotan, AW, Hoyle, S, Humphreys, B, Indermuehle, B, Jacka, CE, Jackson, CA, Jackson, S, Jeganathan, K, Joseph, J, Kendall, R, Kiraly, D, Koribalski, B, Leach, M, Lenc, E, MacLeod, A, Mader, S, Marquarding, M, Marvil, J, McClure-Griffiths, N, McConnell, D, Mirtschin, P, Neuhold, S, Ng, A, Norris, RP, O'Sullivan, J, Pearce, S, Phillips, CJ, Popping, A, Qiao, RY, Reynolds, JE, Roberts, P, Sault, RJ, Schinckel, AET, Serra, P, Shaw, R, Shimwell, TW, Storey, M, Sweetnam, AW, Tzioumis, A, Westmeier, T, Whiting, M, Wilson, CD, Hobbs, G, Heywood, I, Bell, ME, Kerr, M, Rowlinson, A, Johnston, S, Shannon, RM, Voronkov, MA, Ward, C, Banyer, J, Hancock, PJ, Murphy, T, Allison, JR, Amy, SW, Ball, L, Bannister, K, Bock, DCJ, Brodrick, D, Brothers, M, Brown, AJ, Bunton, JD, Chapman, J, Chippendale, AP, Chung, Y, DeBoer, D, Diamond, P, Edwards, PG, Ekers, R, Ferris, RH, Forsyth, R, Gough, R, Grancea, A, Gupta, N, Harvey-Smith, L, Hay, S, Hayman, DB, Hotan, AW, Hoyle, S, Humphreys, B, Indermuehle, B, Jacka, CE, Jackson, CA, Jackson, S, Jeganathan, K, Joseph, J, Kendall, R, Kiraly, D, Koribalski, B, Leach, M, Lenc, E, MacLeod, A, Mader, S, Marquarding, M, Marvil, J, McClure-Griffiths, N, McConnell, D, Mirtschin, P, Neuhold, S, Ng, A, Norris, RP, O'Sullivan, J, Pearce, S, Phillips, CJ, Popping, A, Qiao, RY, Reynolds, JE, Roberts, P, Sault, RJ, Schinckel, AET, Serra, P, Shaw, R, Shimwell, TW, Storey, M, Sweetnam, AW, Tzioumis, A, Westmeier, T, Whiting, M, and Wilson, CD

Abstract

© 2016 The Authors. We use observations from the Boolardy Engineering Test Array (BETA) of the Australian Square Kilometre Array Pathfinder (ASKAP) telescope to search for transient radio sources in the field around the intermittent pulsar PSR J1107-5907. The pulsar is thought to switch between an 'off' state in which no emission is detectable, a weak state and a strong state. We ran three independent transient detection pipelines on two-minute snapshot images from a 13 h BETA observation in order to (1) study the emission from the pulsar, (2) search for other transient emission from elsewhere in the image and (3) to compare the results from the different transient detection pipelines. The pulsar was easily detected as a transient source and, over the course of the observations, it switched into the strong state three times giving a typical time-scale between the strong emission states of 3.7 h. After the first switch it remained in the strong state for almost 40 min. The other strong states lasted less than 4 min. The second state change was confirmed using observations with the Parkes radio telescope. No other transient events were found and we place constraints on the surface density of such events on these time-scales. The high sensitivity Parkes observations enabled us to detect individual bright pulses during the weak state and to study the strong state over a wide observing band. We conclude by showing that future transient surveys with ASKAP will have the potential to probe the intermittent pulsar population.

Published
2016

5. ASKAP HI imaging of the galaxy group IC 1459

Author

Serra, P, Koribalski, B, Kilborn, V, Allison, JR, Amy, SW, Ball, L, Bannister, K, Bell, ME, Bock, DC-J, Bolton, R, Bowen, M, Boyle, B, Broadhurst, S, Brodrick, D, Brothers, M, Bunton, JD, Chapman, J, Cheng, W, Chippendale, AP, Chung, Y, Cooray, F, Cornwell, T, DeBoer, D, Diamond, P, Forsyth, R, Gough, R, Gupta, N, Hampson, GA, Harvey-Smith, L, Hay, S, Hayman, DB, Heywood, I, Hotan, AW, Hoyle, S, Humphreys, B, Indermuehle, B, Jacka, C, Jackson, CA, Jackson, S, Jeganathan, K, Johnston, S, Joseph, J, Kamphuis, P, Leach, M, Lenc, E, Lensson, E, Mackay, S, Marquarding, M, Marvil, J, McClure-Griffiths, N, McConnell, D, Meyer, M, Mirtschin, P, Neuhold, S, Ng, A, Norris, RP, O'Sullivan, J, Pathikulangara, J, Pearce, S, Phillips, C, Popping, A, Qiao, RY, Reynolds, JE, Roberts, P, Sault, RJ, Schinckel, AET, Shaw, R, Shimwell, TW, Staveley-Smith, L, Storey, M, Sweetnam, AW, Troup, E, Tzioumis, A, Voronkov, MA, Westmeier, T, Whiting, M, Wilson, C, Wong, OI, Wu, X, Serra, P, Koribalski, B, Kilborn, V, Allison, JR, Amy, SW, Ball, L, Bannister, K, Bell, ME, Bock, DC-J, Bolton, R, Bowen, M, Boyle, B, Broadhurst, S, Brodrick, D, Brothers, M, Bunton, JD, Chapman, J, Cheng, W, Chippendale, AP, Chung, Y, Cooray, F, Cornwell, T, DeBoer, D, Diamond, P, Forsyth, R, Gough, R, Gupta, N, Hampson, GA, Harvey-Smith, L, Hay, S, Hayman, DB, Heywood, I, Hotan, AW, Hoyle, S, Humphreys, B, Indermuehle, B, Jacka, C, Jackson, CA, Jackson, S, Jeganathan, K, Johnston, S, Joseph, J, Kamphuis, P, Leach, M, Lenc, E, Lensson, E, Mackay, S, Marquarding, M, Marvil, J, McClure-Griffiths, N, McConnell, D, Meyer, M, Mirtschin, P, Neuhold, S, Ng, A, Norris, RP, O'Sullivan, J, Pathikulangara, J, Pearce, S, Phillips, C, Popping, A, Qiao, RY, Reynolds, JE, Roberts, P, Sault, RJ, Schinckel, AET, Shaw, R, Shimwell, TW, Staveley-Smith, L, Storey, M, Sweetnam, AW, Troup, E, Tzioumis, A, Voronkov, MA, Westmeier, T, Whiting, M, Wilson, C, Wong, OI, and Wu, X

Published
2015

6. Dispersion measure variations and their effect on precision pulsar timing

Author

You, XP, Hotan, AW, Ord, SM, Jenet, F, Bhat, NDR, Teoh, A, Hobbs, G, Coles, WA, Manchester, RN, Edwards, R, Bailes, M, Sarkissian, J, Verbiest, JPW, van Straten, W, You, XP, Hotan, AW, Ord, SM, Jenet, F, Bhat, NDR, Teoh, A, Hobbs, G, Coles, WA, Manchester, RN, Edwards, R, Bailes, M, Sarkissian, J, Verbiest, JPW, and van Straten, W

Abstract

We present an analysis of the variations seen in the dispersion measures (DMs) of 20-ms pulsars observed as part of the Parkes Pulsar Timing Array project.We carry out a statistically rigorous structure function analysis for each pulsar and show that the variations seen for most pulsars are consistent with those expected for an interstellar medium characterized by a Kolmogorov turbulence spectrum. The structure functions for PSRs J1045−4509 and J1909−3744 provide the first clear evidence for a large inner scale, possibly due to ion–neutral damping. We also show the effect of the solar wind on the DMs and show that the simple models presently implemented into pulsar timing packages cannot reliably correct for this effect. For the first time we clearly show how DM variations affect pulsar timing residuals and how they can be corrected in order to obtain the highest possible timing precision. Even with our presently limited data span, the residuals (and all parameters derived from the timing) for six of our pulsars have been significantly improved by correcting for the DM variations.

7. The dispersion-brightness relation for fast radio bursts from a wide-field survey.

Author

Shannon RM, Macquart JP, Bannister KW, Ekers RD, James CW, Osłowski S, Qiu H, Sammons M, Hotan AW, Voronkov MA, Beresford RJ, Brothers M, Brown AJ, Bunton JD, Chippendale AP, Haskins C, Leach M, Marquarding M, McConnell D, Pilawa MA, Sadler EM, Troup ER, Tuthill J, Whiting MT, Allison JR, Anderson CS, Bell ME, Collier JD, Gürkan G, Heald G, and Riseley CJ

Abstract

Despite considerable efforts over the past decade, only 34 fast radio bursts-intense bursts of radio emission from beyond our Galaxy-have been reported 1,2 . Attempts to understand the population as a whole have been hindered by the highly heterogeneous nature of the searches, which have been conducted with telescopes of different sensitivities, at a range of radio frequencies, and in environments corrupted by different levels of radio-frequency interference from human activity. Searches have been further complicated by uncertain burst positions and brightnesses-a consequence of the transient nature of the sources and the poor angular resolution of the detecting instruments. The discovery of repeating bursts from one source 3 , and its subsequent localization 4 to a dwarf galaxy at a distance of 3.7 billion light years, confirmed that the population of fast radio bursts is located at cosmological distances. However, the nature of the emission remains elusive. Here we report a well controlled, wide-field radio survey for these bursts. We found 20, none of which repeated during follow-up observations between 185-1,097 hours after the initial detections. The sample includes both the nearest and the most energetic bursts detected so far. The survey demonstrates that there is a relationship between burst dispersion and brightness and that the high-fluence bursts are the nearby analogues of the more distant events found in higher-sensitivity, narrower-field surveys 5 .

Published
2018
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results