Cassiopeia A, Cygnus A, Taurus A, and Virgo A at ultra-low radio frequencies F. de Gasperin, J. Vink, J. P. McKean, A. Asgekar, I. Avruch, M. J. Bentum, R. Blaauw, A. Bonafede, J. W. Broderick, M. Brüggen et al. (52 more) A&A, 635 (2020) A150 Published online: 26 March 2020 DOI: 10.1051/0004-6361/201936844