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

^*Corresponding author for this work

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

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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.

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
DOIs	https://doi.org/10.1093/mnras/stt2200
Publication status	Published - Feb 2014
Externally published	Yes

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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

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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 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",

volume = "438",

pages = "352--367",

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

issn = "0035-8711",

publisher = "Oxford University Press ",

number = "1",

}

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

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

UR - http://www.scopus.com/inward/record.url?scp=84892553019&partnerID=8YFLogxK

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

ER -

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

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