Probabilistic direction-dependent ionospheric calibration for LOFAR-HBA

  title={Probabilistic direction-dependent ionospheric calibration for LOFAR-HBA},
  author={J. G. Albert and Reinout J. van Weeren and Huib T. Intema and Huub J. A. R{\"o}ttgering},
  journal={Astronomy \& Astrophysics},
Direction-dependent calibration and imaging is a vital part of producing radio images that are deep and have a high fidelity and highly dynamic range with a wide-field low-frequency array such as LOFAR. Currently, dedicated facet-based direction-dependent calibration algorithms rely on the assumption that the size of the isoplanatic patch is much larger than the separation between bright in-field calibrators. This assumption is often violated owing to the dynamic nature of the ionosphere, and… 
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