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Estimating Solar Flux Density at Low Radio Frequencies Using a Sky Brightness Model


Sky models have been used in the past to calibrate individual low radio frequency telescopes. In this article we generalize this approach from a single antenna to a two element interferometer, and formulate the problem in a way that allows us to estimate the flux density of the Sun using the normalized cross-correlations (visibilities) measured on a low resolution interferometric baseline. For wide field-of-view instruments, typically the case at low radio frequencies, this approach can provide robust absolute solar flux calibration for well characterized antennas and receiver systems. It can provide a reliable and computationally lean method for extracting parameters of physical interest using a small fraction of the voluminous interferometric data, which can be computationally prohibitively expensive to calibrate and image using conventional approaches. We demonstrate this technique by applying it to data from the Murchison Widefield Array and assess its reliability.

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We acknowledge helpful discussions with Randall Wayth and Budi Juswardy, both at Curtin University, Australia, and their providing estimates of \(T_{\mathrm{Rec}}\) and \(\delta T_{\mathrm{Rec}}\). We also acknowledge helpful comments from Stephen White (Air Force Research Laboratory, Kirtland, NM, USA) and David Webb (Boston College, MA, USA) on an earlier version of the manuscript. This scientific work makes use of the Murchison Radio Astronomy Observatory, operated by CSIRO. We acknowledge the Wajarri Yamatji people being the traditional owners of the Observatory site. Support for the operation of the MWA is provided by the Australian Government Department of Industry and Science and Department of Education (National Collaborative Research Infrastructure Strategy, NCRIS), under a contract to Curtin University administered by Astronomy Australia Limited. We acknowledge the iVEC Petabyte Data Store and the Initiative in Innovative Computing and the CUDA Center for Excellence sponsored by NVIDIA at Harvard University. Facilities: Murchison Widefield Array.

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Correspondence to Divya Oberoi.

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Oberoi, D., Sharma, R. & Rogers, A.E.E. Estimating Solar Flux Density at Low Radio Frequencies Using a Sky Brightness Model. Sol Phys 292, 75 (2017).

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  • Sun: radio radiation
  • Techniques: interferometric