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

Martin Bell; Tara Murphy; David L Kaplan; Paul J Hancock; Bryan Malcolm Gaensler; Jay Banyer; Keith Bannister; Cathryn Trott; Natasha Hurley-Walker; Randall B Wayth; Jean-Pierre Macquart; Wayne Arcus; David Graeme Barnes; Gianni Bernardi; Judd D Bowman; Frank Briggs; John Bunton; Roger Cappallo; Brian E Corey; Avinash Deshpande; Ludovico deSouza; David Emrich; Robert F Goeke; Lincoln Greenhill; Bryna J Hazelton; David Edwin Herne; Jacqueline N Hewitt; Melanie Johnston-Hollitt; Justin C Kasper; Barton B Kincaid; Ronald Koenig; Eric Kratzenberg; Colin J Lonsdale; Mervyn John Lynch; Stephen Russell McWhirter; Daniel A Mitchell; Miguel F Morales; Edward H Morgan; Divya Oberoi; Stephen M Ord; Joseph Pathikulangara; Thiagaraj Prabu; Ronald A Remillard; Alan E E Rogers; Anish A Roshi; Joseph E Salah; Robert John Sault; Natarajan Udaya-Shankar; K S Srivani; James Stevens; Ravi Subrahmanyan; Steven John Tingay; Mark F Waterson; Rachel Lindsey Webster; Alan R Whitney; Andrew Williams; Christopher L Williams; J Stuart B Wyithe

doi:10.1093/mnras/stt2200

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

Martin Bell, Tara Murphy, David L Kaplan, Paul J Hancock, Bryan Malcolm Gaensler, Jay Banyer, Keith Bannister, Cathryn Trott, Natasha Hurley-Walker, Randall B Wayth, Jean-Pierre Macquart, Wayne Arcus, David Graeme Barnes, Gianni Bernardi, Judd D Bowman, Frank Briggs, John Bunton, Roger Cappallo, Brian E Corey, Avinash DeshpandeLudovico deSouza, David Emrich, Robert F Goeke, Lincoln Greenhill, Bryna J Hazelton, David Edwin Herne, Jacqueline N Hewitt, Melanie Johnston-Hollitt, Justin C Kasper, Barton B Kincaid, Ronald Koenig, Eric Kratzenberg, Colin J Lonsdale, Mervyn John Lynch, Stephen Russell McWhirter, Daniel A Mitchell, Miguel F Morales, Edward H Morgan, Divya Oberoi, Stephen M Ord, Joseph Pathikulangara, Thiagaraj Prabu, Ronald A Remillard, Alan E E Rogers, Anish A Roshi, Joseph E Salah, Robert John Sault, Natarajan Udaya-Shankar, K S Srivani, James Stevens, Ravi Subrahmanyan, Steven John Tingay, Mark F Waterson, Rachel Lindsey Webster, Alan R Whitney, Andrew Williams, Christopher L Williams, J Stuart B Wyithe

Monash e-Research Centre

Research output: Contribution to journal › Article › Research › peer-review

54 Citations (Scopus)

Abstract

We present a search for transient and variable radio sources at 154 MHz with the Murchison Widefield Array 32-tile prototype. 51 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 min and there was additional temporal information on day and year time-scales. 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 time-scale variability (26 min). We conclude that this variability is likely caused by simplifications in the calibration strategy or ionospheric effects. On the time-scale of 1 yr 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 ? <7.5 ? 10-5 deg-2 with flux densities >5.5 Jy, and characteristic time-scales of both 26 min and 1 yr.

Original language	English
Pages (from-to)	352 - 367
Number of pages	16
Journal	Monthly Notices of the Royal Astronomical Society
Volume	438
Issue number	1 (Art # stt2200)
DOIs	https://doi.org/10.1093/mnras/stt2200
Publication status	Published - 2014

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10.1093/mnras/stt2200

Cite this

Bell, M., Murphy, T., Kaplan, D. L., Hancock, P. J., Gaensler, B. M., Banyer, J., Bannister, K., Trott, C., Hurley-Walker, N., Wayth, R. B., Macquart, J.-P., Arcus, W., Barnes, D. G., Bernardi, G., Bowman, J. D., Briggs, F., Bunton, J., Cappallo, R., Corey, B. E., ... Wyithe, J. S. B. (2014). A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz. Monthly Notices of the Royal Astronomical Society, 438(1 (Art # stt2200)), 352 - 367. https://doi.org/10.1093/mnras/stt2200

@article{27f42040288943b39da98df7fd92c457,

title = "A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz",

abstract = "We present a search for transient and variable radio sources at 154 MHz with the Murchison Widefield Array 32-tile prototype. 51 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 min and there was additional temporal information on day and year time-scales. 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 time-scale variability (26 min). We conclude that this variability is likely caused by simplifications in the calibration strategy or ionospheric effects. On the time-scale of 1 yr 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 ? <7.5 ? 10-5 deg-2 with flux densities >5.5 Jy, and characteristic time-scales of both 26 min and 1 yr.",

author = "Martin Bell and Tara Murphy and Kaplan, {David L} and Hancock, {Paul J} and Gaensler, {Bryan Malcolm} and Jay Banyer and Keith Bannister and Cathryn Trott and Natasha Hurley-Walker and Wayth, {Randall B} and Jean-Pierre Macquart and Wayne Arcus and Barnes, {David Graeme} and Gianni Bernardi and Bowman, {Judd D} and Frank Briggs and John Bunton and Roger Cappallo and Corey, {Brian E} and Avinash Deshpande and Ludovico deSouza and David Emrich and Goeke, {Robert F} and Lincoln Greenhill and Hazelton, {Bryna J} and Herne, {David Edwin} and Hewitt, {Jacqueline N} and Melanie Johnston-Hollitt and Kasper, {Justin C} and Kincaid, {Barton B} and Ronald Koenig and Eric Kratzenberg and Lonsdale, {Colin J} and Lynch, {Mervyn John} and McWhirter, {Stephen Russell} and Mitchell, {Daniel A} and Morales, {Miguel F} and Morgan, {Edward H} and Divya Oberoi and Ord, {Stephen M} and Joseph Pathikulangara and Thiagaraj Prabu and Remillard, {Ronald A} and Rogers, {Alan E E} and Roshi, {Anish A} and Salah, {Joseph E} and Sault, {Robert John} and Natarajan Udaya-Shankar and Srivani, {K S} and James Stevens and Ravi Subrahmanyan and Tingay, {Steven John} and Waterson, {Mark F} and Webster, {Rachel Lindsey} and Whitney, {Alan R} and Andrew Williams and Williams, {Christopher L} and Wyithe, {J Stuart B}",

year = "2014",

doi = "10.1093/mnras/stt2200",

language = "English",

volume = "438",

pages = "352 -- 367",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press",

number = "1 (Art # stt2200)",

}

Bell, M, Murphy, T, Kaplan, DL, Hancock, PJ, Gaensler, BM, Banyer, J, Bannister, K, Trott, C, Hurley-Walker, N, Wayth, RB, Macquart, J-P, Arcus, W, Barnes, DG, Bernardi, G, Bowman, JD, Briggs, F, Bunton, J, Cappallo, R, Corey, BE, Deshpande, A, deSouza, L, Emrich, D, Goeke, RF, Greenhill, L, Hazelton, BJ, Herne, DE, Hewitt, JN, Johnston-Hollitt, M, Kasper, JC, Kincaid, BB, Koenig, R, Kratzenberg, E, Lonsdale, CJ, Lynch, MJ, McWhirter, SR, Mitchell, DA, Morales, MF, Morgan, EH, Oberoi, D, Ord, SM, Pathikulangara, J, Prabu, T, Remillard, RA, Rogers, AEE, Roshi, AA, Salah, JE, Sault, RJ, Udaya-Shankar, N, Srivani, KS, Stevens, J, Subrahmanyan, R, Tingay, SJ, Waterson, MF, Webster, RL, Whitney, AR, Williams, A, Williams, CL & Wyithe, JSB 2014, 'A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz', Monthly Notices of the Royal Astronomical Society, vol. 438, no. 1 (Art # stt2200), pp. 352 - 367. https://doi.org/10.1093/mnras/stt2200

TY - JOUR

T1 - A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz

AU - Bell, Martin

AU - Murphy, Tara

AU - Kaplan, David L

AU - Hancock, Paul J

AU - Gaensler, Bryan Malcolm

AU - Banyer, Jay

AU - Bannister, Keith

AU - Trott, Cathryn

AU - Hurley-Walker, Natasha

AU - Wayth, Randall B

AU - Macquart, Jean-Pierre

AU - Arcus, Wayne

AU - Barnes, David Graeme

AU - Bernardi, Gianni

AU - Bowman, Judd D

AU - Briggs, Frank

AU - Bunton, John

AU - Cappallo, Roger

AU - Corey, Brian E

AU - Deshpande, Avinash

AU - deSouza, Ludovico

AU - Emrich, David

AU - Goeke, Robert F

AU - Greenhill, Lincoln

AU - Hazelton, Bryna J

AU - Herne, David Edwin

AU - Hewitt, Jacqueline N

AU - Johnston-Hollitt, Melanie

AU - Kasper, Justin C

AU - Kincaid, Barton B

AU - Koenig, Ronald

AU - Kratzenberg, Eric

AU - Lonsdale, Colin J

AU - Lynch, Mervyn John

AU - McWhirter, Stephen Russell

AU - Mitchell, Daniel A

AU - Morales, Miguel F

AU - Morgan, Edward H

AU - Oberoi, Divya

AU - Ord, Stephen M

AU - Pathikulangara, Joseph

AU - Prabu, Thiagaraj

AU - Remillard, Ronald A

AU - Rogers, Alan E E

AU - Roshi, Anish A

AU - Salah, Joseph E

AU - Sault, Robert John

AU - Udaya-Shankar, Natarajan

AU - Srivani, K S

AU - Stevens, James

AU - Subrahmanyan, Ravi

AU - Tingay, Steven John

AU - Waterson, Mark F

AU - Webster, Rachel Lindsey

AU - Whitney, Alan R

AU - Williams, Andrew

AU - Williams, Christopher L

AU - Wyithe, J Stuart B

PY - 2014

Y1 - 2014

N2 - We present a search for transient and variable radio sources at 154 MHz with the Murchison Widefield Array 32-tile prototype. 51 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 min and there was additional temporal information on day and year time-scales. 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 time-scale variability (26 min). We conclude that this variability is likely caused by simplifications in the calibration strategy or ionospheric effects. On the time-scale of 1 yr 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 ? <7.5 ? 10-5 deg-2 with flux densities >5.5 Jy, and characteristic time-scales of both 26 min and 1 yr.

AB - We present a search for transient and variable radio sources at 154 MHz with the Murchison Widefield Array 32-tile prototype. 51 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 min and there was additional temporal information on day and year time-scales. 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 time-scale variability (26 min). We conclude that this variability is likely caused by simplifications in the calibration strategy or ionospheric effects. On the time-scale of 1 yr 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 ? <7.5 ? 10-5 deg-2 with flux densities >5.5 Jy, and characteristic time-scales of both 26 min and 1 yr.

U2 - 10.1093/mnras/stt2200

DO - 10.1093/mnras/stt2200

M3 - Article

SN - 0035-8711

VL - 438

SP - 352

EP - 367

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 1 (Art # stt2200)

ER -