Comparing Redundant and Sky-model-based Interferometric Calibration: A First Look with Phase II of the MWA

W. Li, J. C. Pober, B. J. Hazelton, N. Barry, M. F. Morales, I. Sullivan, A. R. Parsons, Z. S. Ali, J. S. Dillon, A. P. Beardsley, Judd Bowman, F. Briggs, R. Byrne, P. Carroll, B. Crosse, D. Emrich, A. Ewall-Wice, L. Feng, T. M.O. Franzen, J. N. HewittL. Horsley, Daniel Jacobs, M. Johnston-Hollitt, C. Jordan, R. C. Joseph, D. L. Kaplan, D. Kenney, H. Kim, P. Kittiwisit, A. Lanman, J. Line, B. McKinley, D. A. Mitchell, S. Murray, A. Neben, A. R. Offringa, D. Pallot, S. Paul, B. Pindor, P. Procopio, M. Rahimi, J. Riding, S. K. Sethi, N. Udaya Shankar, K. Steele, R. Subrahmanian, M. Tegmark, N. Thyagarajan, S. J. Tingay, C. Trott, M. Walker, R. B. Wayth, R. L. Webster, A. Williams, C. Wu, S. Wyithe

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Interferometric arrays seeking to measure the 21 cm signal from the epoch of reionization (EOR) must contend with overwhelmingly bright emission from foreground sources. Accurate recovery of the 21 cm signal will require precise calibration of the array, and several new avenues for calibration have been pursued in recent years, including methods using redundancy in the antenna configuration. The newly upgraded Phase II of Murchison Widefield Array (MWA) is the first interferometer that has large numbers of redundant baselines while retaining good instantaneous UV coverage. This array therefore provides a unique opportunity to compare redundant calibration with sky-model-based algorithms. In this paper, we present the first results from comparing both calibration approaches with MWA Phase II observations. For redundant calibration, we use the package OMNICAL and produce sky-based calibration solutions with the analysis package Fast Holographic Deconvolution (FHD). There are three principal results: (1) We report the success of OMNICAL on observations of ORBComm satellites, showing substantial agreement between redundant visibility measurements after calibration. (2) We directly compare OMNICAL calibration solutions with those from FHD and demonstrate that these two different calibration schemes give extremely similar results. (3) We explore improved calibration by combining OMNICAL and FHD. We evaluate these combined methods using power spectrum techniques developed for EOR analysis and find evidence for marginal improvements mitigating artifacts in the power spectrum. These results are likely limited by the signal-to-noise ratio in the 6 hr of data used, but they suggest future directions for combining these two calibration schemes.

Original languageEnglish (US)
Article number170
JournalAstrophysical Journal
Volume863
Issue number2
DOIs
StatePublished - Aug 20 2018

Fingerprint

sky
calibration
power spectra
time measurement
deconvolution
redundancy
retaining
visibility
artifacts
signal to noise ratios
interferometers
antennas
recovery
configurations
interferometer
signal-to-noise ratio
artifact
antenna

Keywords

  • dark ages, reionization, first stars
  • instrumentation: interferometers
  • methods: data analysis
  • techniques: interferometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Li, W., Pober, J. C., Hazelton, B. J., Barry, N., Morales, M. F., Sullivan, I., ... Wyithe, S. (2018). Comparing Redundant and Sky-model-based Interferometric Calibration: A First Look with Phase II of the MWA. Astrophysical Journal, 863(2), [170]. https://doi.org/10.3847/1538-4357/aad3c3

Comparing Redundant and Sky-model-based Interferometric Calibration : A First Look with Phase II of the MWA. / Li, W.; Pober, J. C.; Hazelton, B. J.; Barry, N.; Morales, M. F.; Sullivan, I.; Parsons, A. R.; Ali, Z. S.; Dillon, J. S.; Beardsley, A. P.; Bowman, Judd; Briggs, F.; Byrne, R.; Carroll, P.; Crosse, B.; Emrich, D.; Ewall-Wice, A.; Feng, L.; Franzen, T. M.O.; Hewitt, J. N.; Horsley, L.; Jacobs, Daniel; Johnston-Hollitt, M.; Jordan, C.; Joseph, R. C.; Kaplan, D. L.; Kenney, D.; Kim, H.; Kittiwisit, P.; Lanman, A.; Line, J.; McKinley, B.; Mitchell, D. A.; Murray, S.; Neben, A.; Offringa, A. R.; Pallot, D.; Paul, S.; Pindor, B.; Procopio, P.; Rahimi, M.; Riding, J.; Sethi, S. K.; Udaya Shankar, N.; Steele, K.; Subrahmanian, R.; Tegmark, M.; Thyagarajan, N.; Tingay, S. J.; Trott, C.; Walker, M.; Wayth, R. B.; Webster, R. L.; Williams, A.; Wu, C.; Wyithe, S.

In: Astrophysical Journal, Vol. 863, No. 2, 170, 20.08.2018.

Research output: Contribution to journalArticle

Li, W, Pober, JC, Hazelton, BJ, Barry, N, Morales, MF, Sullivan, I, Parsons, AR, Ali, ZS, Dillon, JS, Beardsley, AP, Bowman, J, Briggs, F, Byrne, R, Carroll, P, Crosse, B, Emrich, D, Ewall-Wice, A, Feng, L, Franzen, TMO, Hewitt, JN, Horsley, L, Jacobs, D, Johnston-Hollitt, M, Jordan, C, Joseph, RC, Kaplan, DL, Kenney, D, Kim, H, Kittiwisit, P, Lanman, A, Line, J, McKinley, B, Mitchell, DA, Murray, S, Neben, A, Offringa, AR, Pallot, D, Paul, S, Pindor, B, Procopio, P, Rahimi, M, Riding, J, Sethi, SK, Udaya Shankar, N, Steele, K, Subrahmanian, R, Tegmark, M, Thyagarajan, N, Tingay, SJ, Trott, C, Walker, M, Wayth, RB, Webster, RL, Williams, A, Wu, C & Wyithe, S 2018, 'Comparing Redundant and Sky-model-based Interferometric Calibration: A First Look with Phase II of the MWA', Astrophysical Journal, vol. 863, no. 2, 170. https://doi.org/10.3847/1538-4357/aad3c3
Li, W. ; Pober, J. C. ; Hazelton, B. J. ; Barry, N. ; Morales, M. F. ; Sullivan, I. ; Parsons, A. R. ; Ali, Z. S. ; Dillon, J. S. ; Beardsley, A. P. ; Bowman, Judd ; Briggs, F. ; Byrne, R. ; Carroll, P. ; Crosse, B. ; Emrich, D. ; Ewall-Wice, A. ; Feng, L. ; Franzen, T. M.O. ; Hewitt, J. N. ; Horsley, L. ; Jacobs, Daniel ; Johnston-Hollitt, M. ; Jordan, C. ; Joseph, R. C. ; Kaplan, D. L. ; Kenney, D. ; Kim, H. ; Kittiwisit, P. ; Lanman, A. ; Line, J. ; McKinley, B. ; Mitchell, D. A. ; Murray, S. ; Neben, A. ; Offringa, A. R. ; Pallot, D. ; Paul, S. ; Pindor, B. ; Procopio, P. ; Rahimi, M. ; Riding, J. ; Sethi, S. K. ; Udaya Shankar, N. ; Steele, K. ; Subrahmanian, R. ; Tegmark, M. ; Thyagarajan, N. ; Tingay, S. J. ; Trott, C. ; Walker, M. ; Wayth, R. B. ; Webster, R. L. ; Williams, A. ; Wu, C. ; Wyithe, S. / Comparing Redundant and Sky-model-based Interferometric Calibration : A First Look with Phase II of the MWA. In: Astrophysical Journal. 2018 ; Vol. 863, No. 2.
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abstract = "Interferometric arrays seeking to measure the 21 cm signal from the epoch of reionization (EOR) must contend with overwhelmingly bright emission from foreground sources. Accurate recovery of the 21 cm signal will require precise calibration of the array, and several new avenues for calibration have been pursued in recent years, including methods using redundancy in the antenna configuration. The newly upgraded Phase II of Murchison Widefield Array (MWA) is the first interferometer that has large numbers of redundant baselines while retaining good instantaneous UV coverage. This array therefore provides a unique opportunity to compare redundant calibration with sky-model-based algorithms. In this paper, we present the first results from comparing both calibration approaches with MWA Phase II observations. For redundant calibration, we use the package OMNICAL and produce sky-based calibration solutions with the analysis package Fast Holographic Deconvolution (FHD). There are three principal results: (1) We report the success of OMNICAL on observations of ORBComm satellites, showing substantial agreement between redundant visibility measurements after calibration. (2) We directly compare OMNICAL calibration solutions with those from FHD and demonstrate that these two different calibration schemes give extremely similar results. (3) We explore improved calibration by combining OMNICAL and FHD. We evaluate these combined methods using power spectrum techniques developed for EOR analysis and find evidence for marginal improvements mitigating artifacts in the power spectrum. These results are likely limited by the signal-to-noise ratio in the 6 hr of data used, but they suggest future directions for combining these two calibration schemes.",
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T1 - Comparing Redundant and Sky-model-based Interferometric Calibration

T2 - A First Look with Phase II of the MWA

AU - Li, W.

AU - Pober, J. C.

AU - Hazelton, B. J.

AU - Barry, N.

AU - Morales, M. F.

AU - Sullivan, I.

AU - Parsons, A. R.

AU - Ali, Z. S.

AU - Dillon, J. S.

AU - Beardsley, A. P.

AU - Bowman, Judd

AU - Briggs, F.

AU - Byrne, R.

AU - Carroll, P.

AU - Crosse, B.

AU - Emrich, D.

AU - Ewall-Wice, A.

AU - Feng, L.

AU - Franzen, T. M.O.

AU - Hewitt, J. N.

AU - Horsley, L.

AU - Jacobs, Daniel

AU - Johnston-Hollitt, M.

AU - Jordan, C.

AU - Joseph, R. C.

AU - Kaplan, D. L.

AU - Kenney, D.

AU - Kim, H.

AU - Kittiwisit, P.

AU - Lanman, A.

AU - Line, J.

AU - McKinley, B.

AU - Mitchell, D. A.

AU - Murray, S.

AU - Neben, A.

AU - Offringa, A. R.

AU - Pallot, D.

AU - Paul, S.

AU - Pindor, B.

AU - Procopio, P.

AU - Rahimi, M.

AU - Riding, J.

AU - Sethi, S. K.

AU - Udaya Shankar, N.

AU - Steele, K.

AU - Subrahmanian, R.

AU - Tegmark, M.

AU - Thyagarajan, N.

AU - Tingay, S. J.

AU - Trott, C.

AU - Walker, M.

AU - Wayth, R. B.

AU - Webster, R. L.

AU - Williams, A.

AU - Wu, C.

AU - Wyithe, S.

PY - 2018/8/20

Y1 - 2018/8/20

N2 - Interferometric arrays seeking to measure the 21 cm signal from the epoch of reionization (EOR) must contend with overwhelmingly bright emission from foreground sources. Accurate recovery of the 21 cm signal will require precise calibration of the array, and several new avenues for calibration have been pursued in recent years, including methods using redundancy in the antenna configuration. The newly upgraded Phase II of Murchison Widefield Array (MWA) is the first interferometer that has large numbers of redundant baselines while retaining good instantaneous UV coverage. This array therefore provides a unique opportunity to compare redundant calibration with sky-model-based algorithms. In this paper, we present the first results from comparing both calibration approaches with MWA Phase II observations. For redundant calibration, we use the package OMNICAL and produce sky-based calibration solutions with the analysis package Fast Holographic Deconvolution (FHD). There are three principal results: (1) We report the success of OMNICAL on observations of ORBComm satellites, showing substantial agreement between redundant visibility measurements after calibration. (2) We directly compare OMNICAL calibration solutions with those from FHD and demonstrate that these two different calibration schemes give extremely similar results. (3) We explore improved calibration by combining OMNICAL and FHD. We evaluate these combined methods using power spectrum techniques developed for EOR analysis and find evidence for marginal improvements mitigating artifacts in the power spectrum. These results are likely limited by the signal-to-noise ratio in the 6 hr of data used, but they suggest future directions for combining these two calibration schemes.

AB - Interferometric arrays seeking to measure the 21 cm signal from the epoch of reionization (EOR) must contend with overwhelmingly bright emission from foreground sources. Accurate recovery of the 21 cm signal will require precise calibration of the array, and several new avenues for calibration have been pursued in recent years, including methods using redundancy in the antenna configuration. The newly upgraded Phase II of Murchison Widefield Array (MWA) is the first interferometer that has large numbers of redundant baselines while retaining good instantaneous UV coverage. This array therefore provides a unique opportunity to compare redundant calibration with sky-model-based algorithms. In this paper, we present the first results from comparing both calibration approaches with MWA Phase II observations. For redundant calibration, we use the package OMNICAL and produce sky-based calibration solutions with the analysis package Fast Holographic Deconvolution (FHD). There are three principal results: (1) We report the success of OMNICAL on observations of ORBComm satellites, showing substantial agreement between redundant visibility measurements after calibration. (2) We directly compare OMNICAL calibration solutions with those from FHD and demonstrate that these two different calibration schemes give extremely similar results. (3) We explore improved calibration by combining OMNICAL and FHD. We evaluate these combined methods using power spectrum techniques developed for EOR analysis and find evidence for marginal improvements mitigating artifacts in the power spectrum. These results are likely limited by the signal-to-noise ratio in the 6 hr of data used, but they suggest future directions for combining these two calibration schemes.

KW - dark ages, reionization, first stars

KW - instrumentation: interferometers

KW - methods: data analysis

KW - techniques: interferometric

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