A survey for transients and variables with the murchison widefield array 32-tile prototype at 154 MHz

M. E. Bell; T. Murphy; D. L. Kaplan; P. Hancock; B. M. Gaensler; J. Banyer; K. Bannister; C. Trott; N. Hurley-Walker; R. B. Wayth; J. P. Macquart; W. Arcus; D. Barnes; G. Bernardi; J. D. Bowman; F. Briggs; J. D. Bunton; R. J. Cappallo; B. E. Corey; A. Deshpande; L. Desouza; D. Emrich; R. Goeke; L. J. Greenhill; B. J. Hazelton; D. Herne; J. N. Hewitt; M. Johnston-Hollitt; J. C. Kasper; B. B. Kincaid; R. Koenig; E. Kratzenberg; C. J. Lonsdale; M. J. Lynch; S. R. Mcwhirter; D. A. Mitchell; M. F. Morales; E. Morgan; D. Oberoi; S. M. Ord; J. Pathikulangara; T. Prabu; R. A. Remillard; A. E.E. Rogers; A. Roshi; J. E. Salah; R. J. Sault; N. Udaya Shankar; K. S. Srivani; J. Stevens; R. Subrahmanyan; S. J. Tingay; M. Waterson; R. L. Webster; A. R. Whitney; A. Williams; C. L. Williams; J. S.B. Wyithe

doi:10.1093/mnras/stt2200

A survey for transients and variables with the murchison widefield array 32-tile prototype at 154 MHz

M. E. Bell, T. Murphy, D. L. Kaplan, P. Hancock, B. M. Gaensler, J. Banyer, K. Bannister, C. Trott, N. Hurley-Walker, R. B. Wayth, J. P. Macquart, W. Arcus, D. Barnes, G. Bernardi, J. D. Bowman, F. Briggs, J. D. Bunton, R. J. Cappallo, B. E. Corey, A. DeshpandeL. Desouza, D. Emrich, R. Goeke, L. J. Greenhill, B. J. Hazelton, D. Herne, J. N. Hewitt, M. Johnston-Hollitt, J. C. Kasper, B. B. Kincaid, R. Koenig, E. Kratzenberg, C. J. Lonsdale, M. J. Lynch, S. R. Mcwhirter, D. A. Mitchell, M. F. Morales, E. Morgan, D. Oberoi, S. M. Ord, J. Pathikulangara, T. Prabu, R. A. Remillard, A. E.E. Rogers, A. Roshi, J. E. Salah, R. J. Sault, N. Udaya Shankar, K. S. Srivani, J. Stevens, R. Subrahmanyan, S. J. Tingay, M. Waterson, R. L. Webster, A. R. Whitney, A. Williams, C. L. Williams, J. S.B. Wyithe

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54 Scopus citations

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 ρ < 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 (US)
Pages (from-to)	352-367
Number of pages	16
Journal	Monthly Notices of the Royal Astronomical Society
Volume	438
Issue number	1
DOIs	https://doi.org/10.1093/mnras/stt2200
State	Published - Feb 2014
Externally published	Yes

Keywords

Catalogues
Instrumentation: interferometers
Radio continuum: general
Techniques: image processing

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1093/mnras/stt2200

Cite this

Bell, M. E., Murphy, T., Kaplan, D. L., Hancock, P., Gaensler, B. M., Banyer, J., Bannister, K., Trott, C., Hurley-Walker, N., Wayth, R. B., Macquart, J. P., Arcus, W., Barnes, D., Bernardi, G., Bowman, J. D., Briggs, F., Bunton, J. D., Cappallo, R. J., 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), 352-367. https://doi.org/10.1093/mnras/stt2200

Bell, ME, Murphy, T, Kaplan, DL, Hancock, P, Gaensler, BM, Banyer, J, Bannister, K, Trott, C, Hurley-Walker, N, Wayth, RB, Macquart, JP, Arcus, W, Barnes, D, Bernardi, G, Bowman, JD, Briggs, F, Bunton, JD, Cappallo, RJ, Corey, BE, Deshpande, A, Desouza, L, Emrich, D, Goeke, R, Greenhill, LJ, Hazelton, BJ, Herne, D, Hewitt, JN, Johnston-Hollitt, M, Kasper, JC, Kincaid, BB, Koenig, R, Kratzenberg, E, Lonsdale, CJ, Lynch, MJ, Mcwhirter, SR, Mitchell, DA, Morales, MF, Morgan, E, Oberoi, D, Ord, SM, Pathikulangara, J, Prabu, T, Remillard, RA, Rogers, AEE, Roshi, A, Salah, JE, Sault, RJ, Udaya Shankar, N, Srivani, KS, Stevens, J, Subrahmanyan, R, Tingay, SJ, Waterson, M, 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, pp. 352-367. https://doi.org/10.1093/mnras/stt2200

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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 ρ < 7.5 × 10-5 deg-2 with flux densities >5.5 Jy, and characteristic time-scales of both 26 min and 1 yr.",

keywords = "Catalogues, Instrumentation: interferometers, Radio continuum: general, Techniques: image processing",

author = "Bell, {M. E.} and T. Murphy and Kaplan, {D. L.} and P. Hancock and Gaensler, {B. M.} and J. Banyer and K. Bannister and C. Trott and N. Hurley-Walker and Wayth, {R. B.} and Macquart, {J. P.} and W. Arcus and D. Barnes and G. Bernardi and Bowman, {J. D.} and F. Briggs and Bunton, {J. D.} and Cappallo, {R. J.} and Corey, {B. E.} and A. Deshpande and L. Desouza and D. Emrich and R. Goeke and Greenhill, {L. J.} and Hazelton, {B. J.} and D. Herne and Hewitt, {J. N.} and M. Johnston-Hollitt and Kasper, {J. C.} and Kincaid, {B. B.} and R. Koenig and E. Kratzenberg and Lonsdale, {C. J.} and Lynch, {M. J.} and Mcwhirter, {S. R.} and Mitchell, {D. A.} and Morales, {M. F.} and E. Morgan and D. Oberoi and Ord, {S. M.} and J. Pathikulangara and T. Prabu and Remillard, {R. A.} and Rogers, {A. E.E.} and A. Roshi and Salah, {J. E.} and Sault, {R. J.} and {Udaya Shankar}, N. and Srivani, {K. S.} and J. Stevens and R. Subrahmanyan and Tingay, {S. J.} and M. Waterson and Webster, {R. L.} and Whitney, {A. R.} and A. Williams and Williams, {C. L.} and Wyithe, {J. S.B.}",

year = "2014",

month = feb,

doi = "10.1093/mnras/stt2200",

language = "English (US)",

volume = "438",

pages = "352--367",

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

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TY - JOUR

T1 - A survey for transients and variables with the murchison widefield array 32-tile prototype at 154 MHz

AU - Bell, M. E.

AU - Murphy, T.

AU - Kaplan, D. L.

AU - Hancock, P.

AU - Gaensler, B. M.

AU - Banyer, J.

AU - Bannister, K.

AU - Trott, C.

AU - Hurley-Walker, N.

AU - Wayth, R. B.

AU - Macquart, J. P.

AU - Arcus, W.

AU - Barnes, D.

AU - Bernardi, G.

AU - Bowman, J. D.

AU - Briggs, F.

AU - Bunton, J. D.

AU - Cappallo, R. J.

AU - Corey, B. E.

AU - Deshpande, A.

AU - Desouza, L.

AU - Emrich, D.

AU - Goeke, R.

AU - Greenhill, L. J.

AU - Hazelton, B. J.

AU - Herne, D.

AU - Hewitt, J. N.

AU - Johnston-Hollitt, M.

AU - Kasper, J. C.

AU - Kincaid, B. B.

AU - Koenig, R.

AU - Kratzenberg, E.

AU - Lonsdale, C. J.

AU - Lynch, M. J.

AU - Mcwhirter, S. R.

AU - Mitchell, D. A.

AU - Morales, M. F.

AU - Morgan, E.

AU - Oberoi, D.

AU - Ord, S. M.

AU - Pathikulangara, J.

AU - Prabu, T.

AU - Remillard, R. A.

AU - Rogers, A. E.E.

AU - Roshi, A.

AU - Salah, J. E.

AU - Sault, R. J.

AU - Udaya Shankar, N.

AU - Srivani, K. S.

AU - Stevens, J.

AU - Subrahmanyan, R.

AU - Tingay, S. J.

AU - Waterson, M.

AU - Webster, R. L.

AU - Whitney, A. R.

AU - Williams, A.

AU - Williams, C. L.

AU - Wyithe, J. S.B.

PY - 2014/2

Y1 - 2014/2

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 ρ < 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 ρ < 7.5 × 10-5 deg-2 with flux densities >5.5 Jy, and characteristic time-scales of both 26 min and 1 yr.

KW - Catalogues

KW - Instrumentation: interferometers

KW - Radio continuum: general

KW - Techniques: image processing

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U2 - 10.1093/mnras/stt2200

DO - 10.1093/mnras/stt2200

M3 - Article

AN - SCOPUS:84892553019

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

ER -

A survey for transients and variables with the murchison widefield array 32-tile prototype at 154 MHz

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