Primary beam effects of radio astronomy antennas — II. Modelling the MeerKAT L-band beam. (arXiv:1904.07155v2 [astro-ph.IM] UPDATED)

Primary beam effects of radio astronomy antennas — II. Modelling the MeerKAT L-band beam. (arXiv:1904.07155v2 [astro-ph.IM] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Asad_K/0/1/0/all/0/1">K. M. B. Asad</a> (1, 2, 3, 4), <a href="http://arxiv.org/find/astro-ph/1/au:+Girard_J/0/1/0/all/0/1">J. N. Girard</a> (5), <a href="http://arxiv.org/find/astro-ph/1/au:+Villers_M/0/1/0/all/0/1">M. de Villers</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Ansah_Narh_T/0/1/0/all/0/1">T. Ansah-Narh</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Iheanetu_K/0/1/0/all/0/1">K. Iheanetu</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Smirnov_O/0/1/0/all/0/1">O. Smirnov</a> (2, 4), <a href="http://arxiv.org/find/astro-ph/1/au:+Santos_M/0/1/0/all/0/1">M. G. Santos</a> (3, 4), <a href="http://arxiv.org/find/astro-ph/1/au:+Lehmensiek_R/0/1/0/all/0/1">R. Lehmensiek</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Jonas_J/0/1/0/all/0/1">J. Jonas</a> (2, 4), <a href="http://arxiv.org/find/astro-ph/1/au:+Villiers_D/0/1/0/all/0/1">D. I. L. de Villiers</a> (7), <a href="http://arxiv.org/find/astro-ph/1/au:+Thorat_K/0/1/0/all/0/1">K. Thorat</a> (2, 4, 8), <a href="http://arxiv.org/find/astro-ph/1/au:+Hugo_B/0/1/0/all/0/1">B. Hugo</a> (2, 4), <a href="http://arxiv.org/find/astro-ph/1/au:+Makhathini_S/0/1/0/all/0/1">S. Makhathini</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Jozsa_G/0/1/0/all/0/1">G. I. G. Jozsa</a> (2, 4, 9), <a href="http://arxiv.org/find/astro-ph/1/au:+Sirothia_S/0/1/0/all/0/1">S. K. Sirothia</a> (2, 4) ((2) Department of Physics and Electronics, Rhodes University, Grahamstown, South Africa, (3) Department of Physics and Astronomy, University of the Western Cape, Bellville, Cape Town, South Africa, (4) South African Radio Astronomy Observatory, Cape Town, South Africa, (5) AIM, UMR CEA-CNRS-Paris 7, Irfu, Service d'Astrophysique, France, (6) EMSS Antennas, Stellenbosch, South Africa, (7) Department of Electrical and Electronic Engineering, Stellenbosch University, Stellenbosch, South Africa, (8) Department of Physics, University of Pretoria, South Africa and (9) Argelander-Institut für Astronomie, Germany)

After a decade of design and construction, South Africa’s SKA-MID precursor
MeerKAT has begun its science operations. To make full use of the widefield
capability of the array, it is imperative that we have an accurate model of the
primary beam of its antennas. We have taken available L-band full-polarization
‘astro-holographic’ observations of three antennas and a generic
electromagnetic simulation and created sparse representations of the beams
using principal components and Zernike polynomials. The spectral behaviour of
the spatial coefficients has been modelled using discrete cosine transform. We
have provided the Zernike-based model over a diameter of 10 deg averaged over
the beams of three antennas in an associated software tool (EIDOS) that can be
useful in direction-dependent calibration and imaging. The model is more
accurate for the diagonal elements of the beam Jones matrix and at lower
frequencies. As we get more accurate beam measurements and simulations in the
future, especially for the cross-polarization patterns, our pipeline can be
used to create more accurate sparse representations of MeerKAT beams.

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