Abstract:
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 degrees 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.
