Low-frequency observations of the moon with the murchison widefield array

B. McKinley, F. Briggs, D. L. Kaplan, L. J. Greenhill, G. Bernardi, Judd Bowman, A. De Oliveira-Costa, S. J. Tingay, B. M. Gaensler, D. Oberoi, M. Johnston-Hollitt, W. Arcus, D. Barnes, J. D. Bunton, R. J. Cappallo, B. E. Corey, A. Deshpande, L. Desouza, D. Emrich, R. Goeke & 32 others B. J. Hazelton, D. Herne, J. N. Hewitt, 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, 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, R. B. Wayth, M. Waterson, R. L. Webster, A. R. Whitney, A. Williams, C. L. Williams, J. S B Wyithe

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

A new generation of low-frequency radio telescopes is seeking to observe the redshifted 21cm signal from the epoch of reionization (EoR), requiring innovative methods of calibration and imaging to overcome the difficulties of wide-field low-frequency radio interferometry. Precise calibration will be required to separate the expected small EoR signal from the strong foreground emission at the frequencies of interest between 80 and 300MHz. The Moon may be useful as a calibration source for detection of the EoR signature, as it should have a smooth and predictable thermal spectrum across the frequency band of interest. Initial observations of the Moon with the Murchison Widefield Array 32 tile prototype show that the Moon does exhibit a similar trend to that expected for a cool thermally emitting body in the observed frequency range, but that the spectrum is corrupted by reflected radio emission from Earth. In particular, there is an abrupt increase in the observed flux density of the Moon within the internationally recognized frequency modulated (FM) radio band. The observations have implications for future low-frequency surveys and EoR detection experiments that will need to take this reflected emission from the Moon into account. The results also allow us to estimate the equivalent isotropic power emitted by the Earth in the FM band and to determine how bright the Earth might appear at meter wavelengths to an observer beyond our own solar system.

Original languageEnglish (US)
Article number23
JournalAstronomical Journal
Volume145
Issue number1
DOIs
StatePublished - Jan 2013

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natural satellites
moon
Moon
low frequencies
time measurement
radio
calibration
tiles
radio telescopes
radio emission
interferometry
solar system
flux density
frequency ranges
prototypes
signatures
wavelength
trends
estimates
wavelengths

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

McKinley, B., Briggs, F., Kaplan, D. L., Greenhill, L. J., Bernardi, G., Bowman, J., ... Wyithe, J. S. B. (2013). Low-frequency observations of the moon with the murchison widefield array. Astronomical Journal, 145(1), [23]. https://doi.org/10.1088/0004-6256/145/1/23

Low-frequency observations of the moon with the murchison widefield array. / McKinley, B.; Briggs, F.; Kaplan, D. L.; Greenhill, L. J.; Bernardi, G.; Bowman, Judd; De Oliveira-Costa, A.; Tingay, S. J.; Gaensler, B. M.; Oberoi, D.; Johnston-Hollitt, M.; Arcus, W.; Barnes, D.; Bunton, J. D.; Cappallo, R. J.; Corey, B. E.; Deshpande, A.; Desouza, L.; Emrich, D.; Goeke, R.; Hazelton, B. J.; Herne, D.; Hewitt, J. N.; Kasper, J. C.; Kincaid, B. B.; Koenig, R.; Kratzenberg, E.; Lonsdale, C. J.; Lynch, M. J.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Ord, S. M.; Pathikulangara, J.; Prabu, T.; Remillard, R. A.; Rogers, A. E E; Roshi, A.; Salah, J. E.; Sault, R. J.; Udaya Shankar, N.; Srivani, K. S.; Stevens, J.; Subrahmanyan, R.; Wayth, R. B.; Waterson, M.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wyithe, J. S B.

In: Astronomical Journal, Vol. 145, No. 1, 23, 01.2013.

Research output: Contribution to journalArticle

McKinley, B, Briggs, F, Kaplan, DL, Greenhill, LJ, Bernardi, G, Bowman, J, De Oliveira-Costa, A, Tingay, SJ, Gaensler, BM, Oberoi, D, Johnston-Hollitt, M, Arcus, W, Barnes, D, Bunton, JD, Cappallo, RJ, Corey, BE, Deshpande, A, Desouza, L, Emrich, D, Goeke, R, Hazelton, BJ, Herne, D, Hewitt, JN, Kasper, JC, Kincaid, BB, Koenig, R, Kratzenberg, E, Lonsdale, CJ, Lynch, MJ, McWhirter, SR, Mitchell, DA, Morales, MF, Morgan, E, 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, Wayth, RB, Waterson, M, Webster, RL, Whitney, AR, Williams, A, Williams, CL & Wyithe, JSB 2013, 'Low-frequency observations of the moon with the murchison widefield array', Astronomical Journal, vol. 145, no. 1, 23. https://doi.org/10.1088/0004-6256/145/1/23
McKinley, B. ; Briggs, F. ; Kaplan, D. L. ; Greenhill, L. J. ; Bernardi, G. ; Bowman, Judd ; De Oliveira-Costa, A. ; Tingay, S. J. ; Gaensler, B. M. ; Oberoi, D. ; Johnston-Hollitt, M. ; Arcus, W. ; Barnes, D. ; Bunton, J. D. ; Cappallo, R. J. ; Corey, B. E. ; Deshpande, A. ; Desouza, L. ; Emrich, D. ; Goeke, R. ; Hazelton, B. J. ; Herne, D. ; Hewitt, J. N. ; Kasper, J. C. ; Kincaid, B. B. ; Koenig, R. ; Kratzenberg, E. ; Lonsdale, C. J. ; Lynch, M. J. ; McWhirter, S. R. ; Mitchell, D. A. ; Morales, M. F. ; Morgan, E. ; Ord, S. M. ; Pathikulangara, J. ; Prabu, T. ; Remillard, R. A. ; Rogers, A. E E ; Roshi, A. ; Salah, J. E. ; Sault, R. J. ; Udaya Shankar, N. ; Srivani, K. S. ; Stevens, J. ; Subrahmanyan, R. ; Wayth, R. B. ; Waterson, M. ; Webster, R. L. ; Whitney, A. R. ; Williams, A. ; Williams, C. L. ; Wyithe, J. S B. / Low-frequency observations of the moon with the murchison widefield array. In: Astronomical Journal. 2013 ; Vol. 145, No. 1.
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abstract = "A new generation of low-frequency radio telescopes is seeking to observe the redshifted 21cm signal from the epoch of reionization (EoR), requiring innovative methods of calibration and imaging to overcome the difficulties of wide-field low-frequency radio interferometry. Precise calibration will be required to separate the expected small EoR signal from the strong foreground emission at the frequencies of interest between 80 and 300MHz. The Moon may be useful as a calibration source for detection of the EoR signature, as it should have a smooth and predictable thermal spectrum across the frequency band of interest. Initial observations of the Moon with the Murchison Widefield Array 32 tile prototype show that the Moon does exhibit a similar trend to that expected for a cool thermally emitting body in the observed frequency range, but that the spectrum is corrupted by reflected radio emission from Earth. In particular, there is an abrupt increase in the observed flux density of the Moon within the internationally recognized frequency modulated (FM) radio band. The observations have implications for future low-frequency surveys and EoR detection experiments that will need to take this reflected emission from the Moon into account. The results also allow us to estimate the equivalent isotropic power emitted by the Earth in the FM band and to determine how bright the Earth might appear at meter wavelengths to an observer beyond our own solar system.",
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AU - McKinley, B.

AU - Briggs, F.

AU - Kaplan, D. L.

AU - Greenhill, L. J.

AU - Bernardi, G.

AU - Bowman, Judd

AU - De Oliveira-Costa, A.

AU - Tingay, S. J.

AU - Gaensler, B. M.

AU - Oberoi, D.

AU - Johnston-Hollitt, M.

AU - Arcus, W.

AU - Barnes, D.

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 - Hazelton, B. J.

AU - Herne, D.

AU - Hewitt, J. N.

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 - 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 - Wayth, R. B.

AU - Waterson, M.

AU - Webster, R. L.

AU - Whitney, A. R.

AU - Williams, A.

AU - Williams, C. L.

AU - Wyithe, J. S B

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