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When all measurements are included the radius of a 1.4 M_⊙ neutron star is known to ±4% and the radius of a 2.08 M_⊙ neutron star is known to ±5%."},{"attestation":"unclaimed","claim_id":"C2","kind":"weakest_assumption","source":"verdict.weakest_assumption","status":"machine_extracted","text":"The radius inference assumes specific geometries and temperature distributions for the rotating hot spots plus a particular model for the neutron-star atmosphere and beaming; if these are incorrect the reported credible intervals would shift."},{"attestation":"unclaimed","claim_id":"C3","kind":"one_line_summary","source":"verdict.one_line_summary","status":"machine_extracted","text":"PSR J0740+6620 has an equatorial radius of 13.7^{+2.6}_{-1.5} km, and multi-messenger data constrain 1.4 and 2.08 solar-mass neutron star radii to 12.45 and 12.35 km respectively."},{"attestation":"unclaimed","claim_id":"C4","kind":"headline","source":"verdict.pith_extraction.headline","status":"machine_extracted","text":"The highest-mass neutron star with a reliable radius measurement has an equatorial circumference of 13.7 km."}],"snapshot_sha256":"e37eda48c3188b8b6da01d1db8b182a4534562821e0093897f4e7895276bdf12"},"formal_canon":{"evidence_count":2,"snapshot_sha256":"061870db7e82bf9c67924296c6a45a09dbfb9a8b52e45b822bed74afbf25c76f"},"paper":{"abstract_excerpt":"PSR J0740$+$6620 has a gravitational mass of $2.08\\pm 0.07~M_\\odot$, which is the highest reliably determined mass of any neutron star. As a result, a measurement of its radius will provide unique insight into the properties of neutron star core matter at high densities. Here we report a radius measurement based on fits of rotating hot spot patterns to Neutron Star Interior Composition Explorer (NICER) and X-ray Multi-Mirror (XMM-Newton) X-ray observations. We find that the equatorial circumferential radius of PSR J0740$+$6620 is $13.7^{+2.6}_{-1.5}$ km (68%). We apply our measurement, combine","authors_text":"A. J. Dittmann, A. Parthasarathy, C. B. Markwardt, C. L. Baker, E. Fonseca, F. K. Lamb, H. T. Cromartie, I. Cognard, I. Stairs, J. M. Lattimer, K. C. Gendreau, L. Guillemot, M. C. Miller, M. Kerr, M. Loewenstein, M. T. Wolff, P. S. Ray, S. Bogdanov, S. Guillot, S. Manthripragada, S. M. Morsink, S. Pollard, S. Ransom, T. Cazeau, T. Okajima, T. T. Pennucci, W. C. G. Ho, Z. Arzoumanian","cross_cats":["gr-qc","nucl-ex","nucl-th"],"headline":"The highest-mass neutron star with a reliable radius measurement has an equatorial circumference of 13.7 km.","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.HE","submitted_at":"2021-05-14T17:33:32Z","title":"The Radius of PSR J0740+6620 from NICER and XMM-Newton Data"},"references":{"count":130,"internal_anchors":0,"resolved_work":130,"sample":[{"cited_arxiv_id":"","doi":"","is_internal_anchor":false,"ref_index":1,"title":"P., Abbott , R., Abbott , T","work_id":"d2a199c7-3e4f-494a-a673-fd35e35cd2b5","year":2017},{"cited_arxiv_id":"","doi":"","is_internal_anchor":false,"ref_index":2,"title":"2018, Physical Review Letters, 121, 161101","work_id":"697ee3a9-b9ca-4a1a-9ca0-75a8debd07b3","year":2018},{"cited_arxiv_id":"","doi":"","is_internal_anchor":false,"ref_index":3,"title":"2020 a , , 892, L3","work_id":"eed0d4ad-b589-4d61-b4b2-2de60571da07","year":2020},{"cited_arxiv_id":"","doi":"","is_internal_anchor":false,"ref_index":4,"title":"2020 b , , 896, L44","work_id":"3b726685-52da-4ce9-a7a1-60bb0bcf8e71","year":2020},{"cited_arxiv_id":"","doi":"","is_internal_anchor":false,"ref_index":5,"title":"2021, arXiv e-prints, arXiv:2102.10767","work_id":"6d583897-8daa-4f36-b492-e1f260ac67e6","year":2021}],"snapshot_sha256":"9da541b9060d90bb69d0b7d520b46ca01f0a228bed76bd6be141fc6758a3cd2e"},"source":{"id":"2105.06979","kind":"arxiv","version":1},"verdict":{"created_at":"2026-05-17T06:54:17.506067Z","id":"6c239ac9-cadf-4948-a1bb-77d8ac3f1e4f","model_set":{"reader":"grok-4.3"},"one_line_summary":"PSR J0740+6620 has an equatorial radius of 13.7^{+2.6}_{-1.5} km, and multi-messenger data constrain 1.4 and 2.08 solar-mass neutron star radii to 12.45 and 12.35 km respectively.","pipeline_version":"pith-pipeline@v0.9.0","pith_extraction_headline":"The highest-mass neutron star with a reliable radius measurement has an equatorial circumference of 13.7 km.","strongest_claim":"We find that the equatorial circumferential radius of PSR J0740+6620 is 13.7^{+2.6}_{-1.5} km (68%). When all measurements are included the radius of a 1.4 M_⊙ neutron star is known to ±4% and the radius of a 2.08 M_⊙ neutron star is known to ±5%.","weakest_assumption":"The radius inference assumes specific geometries and temperature distributions for the rotating hot spots plus a particular model for the neutron-star atmosphere and beaming; if these are incorrect the reported credible intervals would shift."}},"verdict_id":"6c239ac9-cadf-4948-a1bb-77d8ac3f1e4f"}}],"author_attestations":[],"timestamp_anchors":[],"storage_attestations":[],"citation_signatures":[],"replication_records":[],"corrections":[],"mirror_hints":[],"record_created":{"event_id":"sha256:c40b64eb4b3417750ab5ef9452f3fad03f4ae23e7b699f37dc40f393ac1d2f37","target":"record","created_at":"2026-05-17T23:38:14Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"attestation_state":"computed","canonical_record":{"metadata":{"abstract_canon_sha256":"e14a9d49e7e5a4b5dd280f59b2497da20462ff7216931ffad06c33dd9f3f1da6","cross_cats_sorted":["gr-qc","nucl-ex","nucl-th"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.HE","submitted_at":"2021-05-14T17:33:32Z","title_canon_sha256":"b0015ddd7e9a2e5914c7cc63ada940693b6fe3f00776e4eb2f1eca7cbdb426ad"},"schema_version":"1.0","source":{"id":"2105.06979","kind":"arxiv","version":1}},"canonical_sha256":"993f7c0a0896d03947d0807213fd1b24a0bf85ca011bded417e8875c354b5585","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"993f7c0a0896d03947d0807213fd1b24a0bf85ca011bded417e8875c354b5585","first_computed_at":"2026-05-17T23:38:14.765517Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-17T23:38:14.765517Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"JkrmrC0xg11We6N1VMBCIcXof4RKyYp7kiQkDDdTBJ/472WJlTtGH9q/eGVWHpPTl7PHpXyIR5EBl5PhNO6JDw==","signature_status":"signed_v1","signed_at":"2026-05-17T23:38:14.766076Z","signed_message":"canonical_sha256_bytes"},"source_id":"2105.06979","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:c40b64eb4b3417750ab5ef9452f3fad03f4ae23e7b699f37dc40f393ac1d2f37","sha256:0e51d570bf57912e9b807e742b60560fbf15ebb1b954ce14f69f967e6059bda5"],"state_sha256":"9dfcc38f97ac1b3a1f478a18d98e6b39c9d93b927ae3775a4f40b5a863544024"}