{"paper":{"title":"Cassiopeia A, Cygnus A, Taurus A, and Virgo A at ultra-low radio frequencies","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["astro-ph.GA","astro-ph.IM"],"primary_cat":"astro-ph.HE","authors_text":"A. Asgekar, A. Bonafede, A.J. van der Horst, A. Krankowski, A. Nelles, A.R. Offringa, A. Rowlinson, A. Shulevski, A. van Ardenne, A.W. Gunst, B. Ciardi, C. Vocks, D. Engels, D.J. Schwarz, E. Orru, F. Breitling, F. De Gasperin, G. Heald, G. Mann, G. Miley, H. Paas, H.R. Butcher, J. Eisloffel, J. Horandel, J.P. McKean, J. Vink, L.V.E. Koopmans, M.A. Garrett, M. Bruggen, M.C. Toribio, M. de Vos, M.J. Bentum, M.J. Norden, M. Mevius, M. Pandey-Pommier, M.P. van Haarlem, M. Soida, M. Tagger, O. Smirnov, O. Wucknitz, P. Maat, P. Zarka, P. Zucca, R.A. Fallows, R. Blaauw, R. J. van Weeren, R. Pizzo, S. Duscha, T.M.O. Franzen, V. Cuciti, W.N. Brouw, W. Reich","submitted_at":"2020-02-24T18:22:38Z","abstract_excerpt":"The four persistent radio sources in the northern sky with the highest flux density at metre wavelengths are Cassiopeia A, Cygnus A, Taurus A, and Virgo A; collectively they are called the A-team. Their flux densities at ultra-low frequencies (<100 MHz) can reach several thousands of janskys, and they often contaminate observations of the low-frequency sky by interfering with image processing. Furthermore, these sources are foreground objects for all-sky observations hampering the study of faint signals, such as the cosmological 21 cm line from the epoch of reionisation.\n  We aim to produce ro"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2002.10431","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2002.10431/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}