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5 results on '"Nunhokee, Chuneeta Devi"'

1. A demonstration of the effect of fringe-rate filtering in the Hydrogen Epoch of Reionization Array delay power spectrum pipeline

Author

Garsden, Hugh, Bull, Philip, Wilensky, Mike, Abdurashidova, Zuhra, Adams, Tyrone, Aguirre, James E., Alexander, Paul, Ali, Zaki S., Baartman, Rushelle, Balfour, Yanga, Beardsley, Adam P., Berkhout, Lindsay M., Bernardi, Gianni, Billings, Tashalee S., Bowman, Judd D., Bradley, Richard F., Burba, Jacob, Carey, Steven, Carilli, Chris L., Chen, Kai-Feng, Cheng, Carina, Choudhuri, Samir, DeBoer, David R., Acedo, Eloy de Lera, Dexter, Matt, Dillon, Joshua S., Dynes, Scott, Eksteen, Nico, Ely, John, Ewall-Wice, Aaron, Fagnoni, Nicolas, Fritz, Randall, Furlanetto, Steven R., Gale-Sides, Kingsley, Gehlot, Bharat Kumar, Ghosh, Abhik, Glendenning, Brian, Gorce, Adelie, Gorthi, Deepthi, Greig, Bradley, Grobbelaar, Jasper, Halday, Ziyaad, Hazelton, Bryna J., Hewitt, Jacqueline N., Hickish, Jack, Huang, Tian, Jacobs, Daniel C., Josaitis, Alec, Julius, Austin, Kariseb, MacCalvin, Kern, Nicholas S., Kerrigan, Joshua, Kim, Honggeun, Kittiwisit, Piyanat, Kohn, Saul A., Kolopanis, Matthew, Lanman, Adam, La Plante, Paul, Liu, Adrian, Loots, Anita, Ma, Yin-Zhe, MacMahon, David H. E., Malan, Lourence, Malgas, Cresshim, Malgas, Keith, Marero, Bradley, Martinot, Zachary E., Mesinger, Andrei, Molewa, Mathakane, Morales, Miguel F., Mosiane, Tshegofalang, Murray, Steven G., Neben, Abraham R., Nikolic, Bojan, Nunhokee, Chuneeta Devi, Nuwegeld, Hans, Parsons, Aaron R., Pascua, Robert, Patra, Nipanjana, Pieterse, Samantha, Qin, Yuxiang, Rath, Eleanor, Razavi-Ghods, Nima, Riley, Daniel, Robnett, James, Rosie, Kathryn, Santos, Mario G., Sims, Peter, Singh, Saurabh, Storer, Dara, Swarts, Hilton, Tan, Jianrong, Thyagarajan, Nithyanandan, van Wyngaarden, Pieter, Williams, Peter K. G., Xu, Zhilei, and Zheng, Haoxuan

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Radio interferometers targeting the 21cm brightness temperature fluctuations at high redshift are subject to systematic effects that operate over a range of different timescales. These can be isolated by designing appropriate Fourier filters that operate in fringe-rate (FR) space, the Fourier pair of local sidereal time (LST). Applications of FR filtering include separating effects that are correlated with the rotating sky vs. those relative to the ground, down-weighting emission in the primary beam sidelobes, and suppressing noise. FR filtering causes the noise contributions to the visibility data to become correlated in time however, making interpretation of subsequent averaging and error estimation steps more subtle. In this paper, we describe fringe rate filters that are implemented using discrete prolate spheroidal sequences, and designed for two different purposes -- beam sidelobe/horizon suppression (the `mainlobe' filter), and ground-locked systematics removal (the `notch' filter). We apply these to simulated data, and study how their properties affect visibilities and power spectra generated from the simulations. Included is an introduction to fringe-rate filtering and a demonstration of fringe-rate filters applied to simple situations to aid understanding., Comment: 21 pages, 18 figures, submitted to Monthly Notices of the Royal Astronomical Society

Published
2024

2. Hydrogen Epoch of Reionization Array (HERA) Phase II Deployment and Commissioning

Author

Berkhout, Lindsay M., Jacobs, Daniel C., Abdurashidova, Zuhra, Adams, Tyrone, Aguirre, James E., Alexander, Paul, Ali, Zaki S., Baartman, Rushelle, Balfour, Yanga, Beardsley, Adam P., Bernardi, Gianni, Billings, Tashalee S., Bowman, Judd D., Bradley, Richard F., Bull, Philip, Burba, Jacob, Carey, Steven, Carilli, Chris L., Chen, Kai-Feng, Cheng, Carina, Choudhuri, Samir, DeBoer, David R., Acedo, Eloy de Lera, Dexter, Matt, Dillon, Joshua S., Dynes, Scott, Eksteen, Nico, Ely, John, Ewall-Wice, Aaron, Fagnoni, Nicolas, Fritz, Randall, Furlanetto, Steven R., Gale-Sides, Kingsley, Garsden, Hugh, Gehlot, Bharat Kumar, Ghosh, Abhik, Glendenning, Brian, Gorce, Adelie, Gorthi, Deepthi, Greig, Bradley, Grobbelaar, Jasper, Halday, Ziyaad, Hazelton, Bryna J., Hewitt, Jacqueline N., Hickish, Jack, Huang, Tian, Josaitis, Alec, Julius, Austin, Kariseb, MacCalvin, Kern, Nicholas S., Kerrigan, Joshua, Kim, Honggeun, Kittiwisit, Piyanat, Kohn, Saul A., Kolopanis, Matthew, Lanman, Adam, La Plante, Paul, Liu, Adrian, Loots, Anita, Ma, Yin-Zhe, MacMahon, David Harold Edward, Malan, Lourence, Malgas, Cresshim, Malgas, Keith, Marero, Bradley, Martinot, Zachary E., Mesinger, Andrei, Molewa, Mathakane, Morales, Miguel F., Mosiane, Tshegofalang, Murray, Steven G., Neben, Abraham R., Nikolic, Bojan, Nunhokee, Chuneeta Devi, Nuwegeld, Hans, Parsons, Aaron R., Pascua, Robert, Patra, Nipanjana, Pieterse, Samantha, Qin, Yuxiang, Rath, Eleanor, Razavi-Ghods, Nima, Riley, Daniel, Robnett, James, Rosie, Kathryn, Santos, Mario G., Sims, Peter, Singh, Saurabh, Storer, Dara, Swarts, Hilton, Tan, Jianrong, Thyagarajan, Nithyanandan, van Wyngaarden, Pieter, Williams, Peter K. G., Zheng, Haoxuan, and Xu, Zhilei

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

This paper presents the design and deployment of the Hydrogen Epoch of Reionization Array (HERA) phase II system. HERA is designed as a staged experiment targeting 21 cm emission measurements of the Epoch of Reionization. First results from the phase I array are published as of early 2022, and deployment of the phase II system is nearing completion. We describe the design of the phase II system and discuss progress on commissioning and future upgrades. As HERA is a designated Square Kilometer Array (SKA) pathfinder instrument, we also show a number of "case studies" that investigate systematics seen while commissioning the phase II system, which may be of use in the design and operation of future arrays. Common pathologies are likely to manifest in similar ways across instruments, and many of these sources of contamination can be mitigated once the source is identified.

Published
2024
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3. matvis: A matrix-based visibility simulator for fast forward modelling of many-element 21 cm arrays

Author

Kittiwisit, Piyanat, Murray, Steven G., Garsden, Hugh, Bull, Philip, Cain, Christopher, Parsons, Aaron R., Sipple, Jackson, Abdurashidova, Zara, Adams, Tyrone, Aguirre, James E., Alexander, Paul, Ali, Zaki S., Baartman, Rushelle, Balfour, Yanga, Beardsley, Adam P., Berkhout, Lindsay M., Bernardi, Gianni, Billings, Tashalee S., Bowman, Judd D., Bradley, Richard F., Burba, Jacob, Carey, Steven, Carilli, Chris L., Chen, Kai-Feng, Cheng, Carina, Choudhuri, Samir, DeBoer, David R., Acedo, Eloy de Lera, Dexter, Matt, Dillon, Joshua S., Dynes, Scott, Eksteen, Nico, Ely, John, Ewall-Wice, Aaron, Fagnoni, Nicolas, Fritz, Randall, Furlanetto, Steven R., Gale-Sides, Kingsley, Gehlot, Bharat Kumar, Ghosh, Abhik, Glendenning, Brian, Gorce, Adelie, Gorthi, Deepthi, Greig, Bradley, Grobbelaar, Jasper, Halday, Ziyaad, Hazelton, Bryna J., Hewitt, Jacqueline N., Hickish, Jack, Huang, Tian, Jacobs, Daniel C., Josaitis, Alec, Julius, Austin, Kariseb, MacCalvin, Kern, Nicholas S., Kerrigan, Joshua, Kim, Honggeun, Kohn, Saul A., Kolopanis, Matthew, Lanman, Adam, La Plante, Paul, Liu, Adrian, Loots, Anita, Ma, Yin-Zhe, MacMahon, David H. E., Malan, Lourence, Malgas, Cresshim, Malgas, Keith, Marero, Bradley, Martinot, Zachary E., Mesinger, Andrei, Molewa, Mathakane, Morales, Miguel F., Mosiane, Tshegofalang, Neben, Abraham R., Nikolic, Bojan, Nunhokee, Chuneeta Devi, Nuwegeld, Hans, Pascua, Robert, Patra, Nipanjana, Pieterse, Samantha, Qin, Yuxiang, Rath, Eleanor, Razavi-Ghods, Nima, Riley, Daniel, Robnett, James, Rosie, Kathryn, Santos, Mario G., Sims, Peter, Singh, Saurabh, Storer, Dara, Swarts, Hilton, Tan, Jianrong, Thyagarajan, Nithyanandan, van Wyngaarden, Pieter, Williams, Peter K. G., Xu, Zhilei, and Zheng, Haoxuan

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Detection of the faint 21 cm line emission from the Cosmic Dawn and Epoch of Reionisation will require not only exquisite control over instrumental calibration and systematics to achieve the necessary dynamic range of observations but also validation of analysis techniques to demonstrate their statistical properties and signal loss characteristics. A key ingredient in achieving this is the ability to perform high-fidelity simulations of the kinds of data that are produced by the large, many-element, radio interferometric arrays that have been purpose-built for these studies. The large scale of these arrays presents a computational challenge, as one must simulate a detailed sky and instrumental model across many hundreds of frequency channels, thousands of time samples, and tens of thousands of baselines for arrays with hundreds of antennas. In this paper, we present a fast matrix-based method for simulating radio interferometric measurements (visibilities) at the necessary scale. We achieve this through judicious use of primary beam interpolation, fast approximations for coordinate transforms, and a vectorised outer product to expand per-antenna quantities to per-baseline visibilities, coupled with standard parallelisation techniques. We validate the results of this method, implemented in the publicly-available matvis code, against a high-precision reference simulator, and explore its computational scaling on a variety of problems., Comment: 24 pages, 10 figures, accepted to RAS Techniques and Instruments, matvis is publicly available at https://github.com/HERA-Team/matvis

Published
2023

4. Automated Detection of Antenna Malfunctions in Large-N Interferometers: A Case Study with the Hydrogen Epoch of Reionization Array

Author

Storer, Dara, Dillon, Joshua S., Jacobs, Daniel C., Morales, Miguel F., Hazelton, Bryna J., Ewall-Wice, Aaron, Abdurashidova, Zara, Aguirre, James E., Alexander, Paul, Ali, Zaki S., Balfour, Yanga, Beardsley, Adam P., Bernardi, Gianni, Billings, Tashalee S., Bowman, Judd D., Bradley, Richard F., Bull, Philip, Burba, Jacob, Carey, Steven, Carilli, Chris L., Cheng, Carina, DeBoer, David R., Acedo, Eloy de Lera, Dexter, Matt, Dynes, Scott, Ely, John, Fagnoni, Nicolas, Fritz, Randall, Furlanetto, Steven R., Gale-Sides, Kingsley, Glendenning, Brian, Gorthi, Deepthi, Greig, Bradley, Grobbelaar, Jasper, Halday, Ziyaad, Hewitt, Jacqueline N., Hickish, Jack, Huang, Tian, Josaitis, Alec, Julius, Austin, Kariseb, MacCalvin, Kern, Nicholas S., Kerrigan, Joshua, Kittiwisit, Piyanat, Kohn, Saul A., Kolopanis, Matthew, Lanman, Adam, La Plante, Paul, Liu, Adrian, Loots, Anita, MacMahon, David, Malan, Lourence, Malgas, Cresshim, Martinot, Zachary E., Mesinger, Andrei, Molewa, Mathakane, Mosiane, Tshegofalang, Murray, Steven G., Neben, Abraham R., Nikolic, Bojan, Nunhokee, Chuneeta Devi, Parsons, Aaron R., Pascua, Robert, Patra, Nipanjana, Pieterse, Samantha, Pober, Jonathan C., Razavi-Ghods, Nima, Riley, Daniel, Robnett, James, Rosie, Kathryn, Santos, Mario G., Sims, Peter, Singh, Saurabh, Smith, Craig, Tan, Jianrong, Thyagarajan, Nithyanandan, Williams, Peter K. G., and Zheng, Haoxuan

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present a framework for identifying and flagging malfunctioning antennas in large radio interferometers. We outline two distinct categories of metrics designed to detect outliers along known failure modes of large arrays: cross-correlation metrics, based on all antenna pairs, and auto-correlation metrics, based solely on individual antennas. We define and motivate the statistical framework for all metrics used, and present tailored visualizations that aid us in clearly identifying new and existing systematics. We implement these techniques using data from 105 antennas in the Hydrogen Epoch of Reionization Array (HERA) as a case study. Finally, we provide a detailed algorithm for implementing these metrics as flagging tools on real data sets., Comment: 31 pages, 17 figures

Published
2021
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5. Redundant-Baseline Calibration of the Hydrogen Epoch of Reionization Array

Author

Dillon, Joshua S., Lee, Max, Ali, Zaki S., Parsons, Aaron R., Orosz, Naomi, Nunhokee, Chuneeta Devi, La Plante, Paul, Beardsley, Adam P., Kern, Nicholas S., Abdurashidova, Zara, Aguirre, James E., Alexander, Paul, Balfour, Yanga, Bernardi, Gianni, Billings, Tashalee S., Bowman, Judd D., Bradley, Richard F., Bull, Phil, Burba, Jacob, Carey, Steve, Carilli, Chris L., Cheng, Carina, DeBoer, David R., Dexter, Matt, Acedo, Eloy de Lera, Ely, John, Ewall-Wice, Aaron, Fagnoni, Nicolas, Fritz, Randall, Furlanetto, Steven R., Gale-Sides, Kingsley, Glendenning, Brian, Gorthi, Deepthi, Greig, Bradley, Grobbelaar, Jasper, Halday, Ziyaad, Hazelton, Bryna J., Hewitt, Jacqueline N., Hickish, Jack, Jacobs, Daniel C., Julius, Austin, Kerrigan, Joshua, Kittiwisit, Piyanat, Kohn, Saul A., Kolopanis, Matthew, Lanman, Adam, Lekalake, Telalo, Lewis, David, Liu, Adrian, Ma, Yin-Zhe, MacMahon, David, Malan, Lourence, Malgas, Cresshim, Maree, Matthys, Martinot, Zachary E., Matsetela, Eunice, Mesinger, Andrei, Molewa, Mathakane, Morales, Miguel F., Mosiane, Tshegofalang, Murray, Steven, Neben, Abraham R., Nikolic, Bojan, Pascua, Robert, Patra, Nipanjana, Pieterse, Samantha, Pober, Jonathan C., Razavi-Ghods, Nima, Ringuette, Jon, Robnett, James, Rosie, Kathryn, Santos, Mario G., Sims, Peter, Smith, Craig, Syce, Angelo, Tegmark, Max, Thyagarajan, Nithyanandan, Williams, Peter K. G., and Zheng, Haoxuan

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

In 21 cm cosmology, precision calibration is key to the separation of the neutral hydrogen signal from very bright but spectrally-smooth astrophysical foregrounds. The Hydrogen Epoch of Reionization Array (HERA), an interferometer specialized for 21 cm cosmology and now under construction in South Africa, was designed to be largely calibrated using the self-consistency of repeated measurements of the same interferometric modes. This technique, known as "redundant-baseline calibration" resolves most of the internal degrees of freedom in the calibration problem. It assumes, however, on antenna elements with identical primary beams placed precisely on a redundant grid. In this work, we review the detailed implementation of the algorithms enabling redundant-baseline calibration and report results with HERA data. We quantify the effects of real-world non-redundancy and how they compare to the idealized scenario in which redundant measurements differ only in their noise realizations. Finally, we study how non-redundancy can produce spurious temporal structure in our calibration solutions--both in data and in simulations--and present strategies for mitigating that structure., Comment: 24 Pages, 19 Figures. Updated to match the accepted MNRAS version

Published
2020
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