Effects of model incompleteness on the drift-scan calibration of radio telescopes
Creators: name: Gehlot, Bharat K.
name: Jacobs, Daniel C.
name: Bowman, Judd D.
name: Mahesh, Nivedita
name: Murray, Steven G.
name: Kolopanis, Matthew
name: Beardsley, Adam P.
name: Abdurashidova, Zara
name: Aguirre, James E.
name: Alexander, Paul
name: Ali, Zaki S.
name: Balfour, Yanga
name: Bernardi, Gianni
name: Billings, Tashalee S.
name: Bradley, Richard F.
name: Bull, Phil
name: Burba, Jacob
name: Carey, Steve
name: Carilli, Chris L.
name: Cheng, Carina
name: DeBoer, David R.
name: Dexter, Matt
name: Acedo, Eloy de Lera
name: Dillon, Joshua S.
name: Ely, John
name: Ewall-Wice, Aaron
name: Fagnoni, Nicolas
name: Fritz, Randall
name: Furlanetto, Steven R.
name: Gale-Sides, Kingsley
name: Glendenning, Brian
name: Gorthi, Deepthi
name: Greig, Bradley
name: Grobbelaar, Jasper
name: Halday, Ziyaad
name: Hazelton, Bryna J.
name: Hewitt, Jacqueline N.
name: Hickish, Jack
name: Julius, Austin
name: Kern, Nicholas S.
name: Kerrigan, Joshua
name: Kittiwisit, Piyanat
name: Kohn, Saul A.
name: Lanman, Adam
name: La Plante, Paul
name: Lekalake, Telalo
name: Lewis, David
name: Liu, Adrian
name: Ma, Yin-Zhe
name: MacMahon, David
name: Malan, Lourence
name: Malgas, Cresshim
name: Maree, Matthys
name: Martinot, Zachary E.
name: Matsetela, Eunice
name: Mesinger, Andrei
name: Molewa, Mathakane
name: Monsalve, Raul A.
name: Morales, Miguel F.
name: Mosiane, Tshegofalang
name: Neben, Abraham R.
name: Nikolic, Bojan
name: Parsons, Aaron R.
name: Pascua, Robert
name: Patra, Nipanjana
name: Pieterse, Samantha
name: Pober, Jonathan C.
name: Razavi-Ghods, Nima
name: Ringuette, Jon
name: Robnett, James
name: Rosie, Kathryn
name: Santos, Mario G.
name: Sims, Peter
name: Smith, Craig
name: Syce, Angelo
name: Tegmark, Max
name: Thyagarajan, Nithyanandan
name: Williams, Peter K. G.
name: Zheng, Haoxuan
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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 auto-correlations 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.
description: 16 pages, 13 figures, 1 table; accepted for publication in MNRAS main journal