Effects of model incompleteness on the drift-scan calibration of radio telescopes

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

Research output: Contribution to journalArticlepeer-review

Abstract

Precision calibration poses challenges to experiments probing the redshifted 21-cm signal of neutral hydrogen from the Cosmic Dawn and Epoch of Reionization (z ∼30-6). In both interferometric and global signal experiments, systematic calibration is the leading source of error. Though many aspects of calibration have been studied, the overlap between the two types of instruments has received less attention. We investigate the sky based calibration of total power measurements with a HERA dish and an EDGES-style antenna to understand the role of autocorrelations in the calibration of an interferometer and the role of sky in calibrating a total power instrument. Using simulations we study various scenarios such as time variable gain, incomplete sky calibration model, and primary beam model. We find that temporal gain drifts, sky model incompleteness, and beam inaccuracies cause biases in the receiver gain amplitude and the receiver temperature estimates. In some cases, these biases mix spectral structure between beam and sky resulting in spectrally variable gain errors. Applying the calibration method to the HERA and EDGES data, we find good agreement with calibration via the more standard methods. Although instrumental gains are consistent with beam and sky errors similar in scale to those simulated, the receiver temperatures show significant deviations from expected values. While we show that it is possible to partially mitigate biases due to model inaccuracies by incorporating a time-dependent gain model in calibration, the resulting errors on calibration products are larger and more correlated. Completely addressing these biases will require more accurate sky and primary beam models.

Original languageEnglish (US)
Pages (from-to)4578-4592
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Volume506
Issue number3
DOIs
StatePublished - Sep 1 2021
Externally publishedYes

Keywords

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

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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