4 results on '"Offringa AR"'
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2. Calibration and Stokes Imaging with Full Embedded Element Primary Beam Model for the Murchison Widefield Array
- Author
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Sokolowski, M, Colegate, T, Sutinjo, AT, Ung, D, Wayth, R, Hurley-Walker, N, Lenc, E, Pindor, B, Morgan, J, Kaplan, DL, Bell, ME, Callingham, JR, Dwarakanath, KS, For, B-Q, Gaensler, BM, Hancock, PJ, Hindson, L, Johnston-Hollitt, M, Kapinska, AD, McKinley, B, Offringa, AR, Procopio, P, Staveley-Smith, L, Wu, C, Zheng, Q, Sokolowski, M, Colegate, T, Sutinjo, AT, Ung, D, Wayth, R, Hurley-Walker, N, Lenc, E, Pindor, B, Morgan, J, Kaplan, DL, Bell, ME, Callingham, JR, Dwarakanath, KS, For, B-Q, Gaensler, BM, Hancock, PJ, Hindson, L, Johnston-Hollitt, M, Kapinska, AD, McKinley, B, Offringa, AR, Procopio, P, Staveley-Smith, L, Wu, C, and Zheng, Q
- Published
- 2017
3. Ionospheric Modelling using GPS to Calibrate the MWA. I: Comparison of First Order Ionospheric Effects between GPS Models and MWA Observations
- Author
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Arora, BS, Morgan, J, Ord, SM, Tingay, SJ, Hurley-Walker, N, Bell, M, Bernardi, G, Bhat, NDR, Briggs, F, Callingham, JR, Deshpande, AA, Dwarakanath, KS, Ewall-Wice, A, Feng, L, For, B-Q, Hancock, P, Hazelton, BJ, Hindson, L, Jacobs, D, Johnston-Hollitt, M, Kapinska, AD, Kudryavtseva, N, Lenc, E, McKinley, B, Mitchell, D, Oberoi, D, Offringa, AR, Pindor, B, Procopio, P, Riding, J, Staveley-Smith, L, Wayth, RB, Wu, C, Zheng, Q, Bowman, JD, Cappallo, RJ, Corey, BE, Emrich, D, Goeke, R, Greenhill, LJ, Kaplan, DL, Kasper, JC, Kratzenberg, E, Lonsdale, CJ, Lynch, MJ, McWhirter, SR, Morales, MF, Morgan, E, Prabu, T, Rogers, AEE, Roshi, A, Shankar, NU, Srivani, KS, Subrahmanyan, R, Waterson, M, Webster, RL, Whitney, AR, Williams, A, Williams, CL, Arora, BS, Morgan, J, Ord, SM, Tingay, SJ, Hurley-Walker, N, Bell, M, Bernardi, G, Bhat, NDR, Briggs, F, Callingham, JR, Deshpande, AA, Dwarakanath, KS, Ewall-Wice, A, Feng, L, For, B-Q, Hancock, P, Hazelton, BJ, Hindson, L, Jacobs, D, Johnston-Hollitt, M, Kapinska, AD, Kudryavtseva, N, Lenc, E, McKinley, B, Mitchell, D, Oberoi, D, Offringa, AR, Pindor, B, Procopio, P, Riding, J, Staveley-Smith, L, Wayth, RB, Wu, C, Zheng, Q, Bowman, JD, Cappallo, RJ, Corey, BE, Emrich, D, Goeke, R, Greenhill, LJ, Kaplan, DL, Kasper, JC, Kratzenberg, E, Lonsdale, CJ, Lynch, MJ, McWhirter, SR, Morales, MF, Morgan, E, Prabu, T, Rogers, AEE, Roshi, A, Shankar, NU, Srivani, KS, Subrahmanyan, R, Waterson, M, Webster, RL, Whitney, AR, Williams, A, and Williams, CL
- Abstract
We compare first-order (refractive) ionospheric effects seen by the MWA with the ionosphere as inferred from GPS data. The first-order ionosphere manifests itself as a bulk position shift of the observed sources across an MWA field of view. These effects can be computed from global ionosphere maps provided by GPS analysis centres, namely the CODE. However, for precision radio astronomy applications, data from local GPS networks needs to be incorporated into ionospheric modelling. For GPS observations, the ionospheric parameters are biased by GPS receiver instrument delays, among other effects, also known as receiver DCBs. The receiver DCBs need to be estimated for any non-CODE GPS station used for ionosphere modelling. In this work, single GPS station-based ionospheric modelling is performed at a time resolution of 10 min. Also the receiver DCBs are estimated for selected Geoscience Australia GPS receivers, located at Murchison Radio Observatory, Yarragadee, Mount Magnet and Wiluna. The ionospheric gradients estimated from GPS are compared with that inferred from MWA. The ionospheric gradients at all the GPS stations show a correlation with the gradients observed with the MWA. The ionosphere estimates obtained using GPS measurements show promise in terms of providing calibration information for the MWA.
- Published
- 2015
4. The Low-Frequency Environment of the Murchison Widefield Array: Radio-Frequency Interference Analysis and Mitigation
- Author
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Offringa, AR, Wayth, RB, Hurley-Walker, N, Kaplan, DL, Barry, N, Beardsley, AP, Bell, ME, Bernardi, G, Bowman, JD, Briggs, F, Callingham, JR, Cappallo, RJ, Carroll, P, Deshpande, AA, Dillon, JS, Dwarakanath, KS, Ewall-Wice, A, Feng, L, For, B-Q, Gaensler, BM, Greenhill, LJ, Hancock, P, Hazelton, BJ, Hewitt, JN, Hindson, L, Jacobs, DC, Johnston-Hollitt, M, Kapinska, AD, Kim, H-S, Kittiwisit, P, Lenc, E, Line, J, Loeb, A, Lonsdale, CJ, McKinley, B, McWhirter, SR, Mitchell, DA, Morales, MF, Morgan, E, Morgan, J, Neben, AR, Oberoi, D, Ord, SM, Paul, S, Pindor, B, Pober, JC, Prabu, T, Procopio, P, Riding, J, Shankar, NU, Sethi, S, Srivani, KS, Staveley-Smith, L, Subrahmanyan, R, Sullivan, IS, Tegmark, M, Thyagarajan, N, Tingay, SJ, Trott, CM, Webster, RL, Williams, A, Williams, CL, Wu, C, Wyithe, JS, Zheng, Q, Offringa, AR, Wayth, RB, Hurley-Walker, N, Kaplan, DL, Barry, N, Beardsley, AP, Bell, ME, Bernardi, G, Bowman, JD, Briggs, F, Callingham, JR, Cappallo, RJ, Carroll, P, Deshpande, AA, Dillon, JS, Dwarakanath, KS, Ewall-Wice, A, Feng, L, For, B-Q, Gaensler, BM, Greenhill, LJ, Hancock, P, Hazelton, BJ, Hewitt, JN, Hindson, L, Jacobs, DC, Johnston-Hollitt, M, Kapinska, AD, Kim, H-S, Kittiwisit, P, Lenc, E, Line, J, Loeb, A, Lonsdale, CJ, McKinley, B, McWhirter, SR, Mitchell, DA, Morales, MF, Morgan, E, Morgan, J, Neben, AR, Oberoi, D, Ord, SM, Paul, S, Pindor, B, Pober, JC, Prabu, T, Procopio, P, Riding, J, Shankar, NU, Sethi, S, Srivani, KS, Staveley-Smith, L, Subrahmanyan, R, Sullivan, IS, Tegmark, M, Thyagarajan, N, Tingay, SJ, Trott, CM, Webster, RL, Williams, A, Williams, CL, Wu, C, Wyithe, JS, and Zheng, Q
- Abstract
The Murchison Widefield Array is a new low-frequency interferometric radio telescope built in Western Australia at one of the locations of the future Square Kilometre Array. We describe the automated radio-frequency interference detection strategy implemented for the Murchison Widefield Array, which is based on the aoflagger platform, and present 72–231 MHz radio-frequency interference statistics from 10 observing nights. Radio-frequency interference detection removes 1.1% of the data. Radio-frequency interference from digital TV is observed 3% of the time due to occasional ionospheric or atmospheric propagation. After radio-frequency interference detection and excision, almost all data can be calibrated and imaged without further radio-frequency interference mitigation efforts, including observations within the FM and digital TV bands. The results are compared to a previously published Low-Frequency Array radio-frequency interference survey. The remote location of the Murchison Widefield Array results in a substantially cleaner radio-frequency interference environment compared to Low-Frequency Array’s radio environment, but adequate detection of radio-frequency interference is still required before data can be analysed. We include specific recommendations designed to make the Square Kilometre Array more robust to radio-frequency interference, including: the availability of sufficient computing power for radio-frequency interference detection; accounting for radio-frequency interference in the receiver design; a smooth band-pass response; and the capability of radio-frequency interference detection at high time and frequency resolution (second and kHz-scale respectively).
- Published
- 2015
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