A probabilistic approach to direction-dependent ionospheric calibration J. G. Albert, M. S. S. L. Oei, R. J. van Weeren, H. T. Intema and H. J. A. Röttgering A&A, 633 (2020) A77 Published online: 14 January 2020 DOI: 10.1051/0004-6361/201935668