{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2018:UX35GYOYX4M4NDRZI5JNBXPZHF","short_pith_number":"pith:UX35GYOY","canonical_record":{"source":{"id":"1808.06442","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.HE","submitted_at":"2018-08-20T13:30:27Z","cross_cats_sorted":[],"title_canon_sha256":"943f33abf2380174dabd983faed8e6b4e29392ad8428cffcb5bedfe9fecd715a","abstract_canon_sha256":"f809c4f68bced0745151fcb0cb030e030bca4d91b3a92899292f64fb9ce43680"},"schema_version":"1.0"},"canonical_sha256":"a5f7d361d8bf19c68e394752d0ddf939530daac8b0c96ecd08fb9ff045b99702","source":{"kind":"arxiv","id":"1808.06442","version":1},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1808.06442","created_at":"2026-05-18T00:07:44Z"},{"alias_kind":"arxiv_version","alias_value":"1808.06442v1","created_at":"2026-05-18T00:07:44Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1808.06442","created_at":"2026-05-18T00:07:44Z"},{"alias_kind":"pith_short_12","alias_value":"UX35GYOYX4M4","created_at":"2026-05-18T12:32:56Z"},{"alias_kind":"pith_short_16","alias_value":"UX35GYOYX4M4NDRZ","created_at":"2026-05-18T12:32:56Z"},{"alias_kind":"pith_short_8","alias_value":"UX35GYOY","created_at":"2026-05-18T12:32:56Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2018:UX35GYOYX4M4NDRZI5JNBXPZHF","target":"record","payload":{"canonical_record":{"source":{"id":"1808.06442","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.HE","submitted_at":"2018-08-20T13:30:27Z","cross_cats_sorted":[],"title_canon_sha256":"943f33abf2380174dabd983faed8e6b4e29392ad8428cffcb5bedfe9fecd715a","abstract_canon_sha256":"f809c4f68bced0745151fcb0cb030e030bca4d91b3a92899292f64fb9ce43680"},"schema_version":"1.0"},"canonical_sha256":"a5f7d361d8bf19c68e394752d0ddf939530daac8b0c96ecd08fb9ff045b99702","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T00:07:44.901338Z","signature_b64":"ElvJl5UCLu6wqJkST3bW1nvrtVLVU1uD1p8vzbTqXpaguVDlurkzxFBUQkYcRgpVK9qL5t6DTN0GkwlyQdxxBg==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"a5f7d361d8bf19c68e394752d0ddf939530daac8b0c96ecd08fb9ff045b99702","last_reissued_at":"2026-05-18T00:07:44.900747Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T00:07:44.900747Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1808.06442","source_version":1,"attestation_state":"computed"},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T00:07:44Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"eTJNOAmFrPh+Nb1kTepIn448UFvrbdjy9yVyPgoJb/jfbNpDT45ouSkGEZZ/Hzkweks7FZXFWEAItpSsg9tHDw==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-24T15:20:04.987522Z"},"content_sha256":"222261967301bd352355e867987192b3995a3486f3c857f4f6ca1cbcec29606a","schema_version":"1.0","event_id":"sha256:222261967301bd352355e867987192b3995a3486f3c857f4f6ca1cbcec29606a"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2018:UX35GYOYX4M4NDRZI5JNBXPZHF","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"NICER Detection of Strong Photospheric Expansion during a Thermonuclear X-Ray Burst from 4U 1820-30","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.HE","authors_text":"B. LaMarr, C. B. Markwardt, D. Chakrabarty, F. K. Lamb, G. K. Jaisawal, J. Chenevez, J. Homan, J. J. M. in 't Zand, K. C. Gendreau, L. Keek, S. Guillot, S. Mahmoodifar, T. E. Strohmayer, T. G\\\"uver, T. Okajima, Z. Arzoumanian","submitted_at":"2018-08-20T13:30:27Z","abstract_excerpt":"The Neutron Star Interior Composition Explorer (NICER) on the International Space Station (ISS) observed strong photospheric expansion of the neutron star in 4U 1820-30 during a Type I X-ray burst. A thermonuclear helium flash in the star's envelope powered a burst that reached the Eddington limit. Radiation pressure pushed the photosphere out to ~200 km, while the blackbody temperature dropped to 0.45 keV. Previous observations of similar bursts were performed with instruments that are sensitive only above 3 keV, and the burst signal was weak at low temperatures. NICER's 0.2-12 keV passband e"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1808.06442","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":""},"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"},"verdict_id":null},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T00:07:44Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"ud8EdrOu4eRMmi7gpOXRqDHatCfkKfKiSOFKBaaAwZsZjMXEij7oKYjkB2VLwJn7du4lfZ1pGTHOBWJyr3xQDw==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-24T15:20:04.988153Z"},"content_sha256":"e37e549c546d77cb33894ab855bccb69a3005ca9b220c7f6bdb1765874bab8bb","schema_version":"1.0","event_id":"sha256:e37e549c546d77cb33894ab855bccb69a3005ca9b220c7f6bdb1765874bab8bb"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/UX35GYOYX4M4NDRZI5JNBXPZHF/bundle.json","state_url":"https://pith.science/pith/UX35GYOYX4M4NDRZI5JNBXPZHF/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/UX35GYOYX4M4NDRZI5JNBXPZHF/bundle.json","status":"primary"}],"public_keys":[{"key_id":"pith-v1-2026-05","algorithm":"ed25519","format":"raw","public_key_b64":"stVStoiQhXFxp4s2pdzPNoqVNBMojDU/fJ2db5S3CbM=","public_key_hex":"b2d552b68890857171a78b36a5dccf368a953413288c353f7c9d9d6f94b709b3","fingerprint_sha256_b32_first128bits":"RVFV5Z2OI2J3ZUO7ERDEBCYNKS","fingerprint_sha256_hex":"8d4b5ee74e4693bcd1df2446408b0d54","rotates_at":null,"url":"https://pith.science/pith-signing-key.json","notes":"Pith uses this Ed25519 key to sign canonical record SHA-256 digests. Verify with: ed25519_verify(public_key, message=canonical_sha256_bytes, signature=base64decode(signature_b64))."}],"merge_version":"pith-open-graph-merge-v1","built_at":"2026-05-24T15:20:04Z","links":{"resolver":"https://pith.science/pith/UX35GYOYX4M4NDRZI5JNBXPZHF","bundle":"https://pith.science/pith/UX35GYOYX4M4NDRZI5JNBXPZHF/bundle.json","state":"https://pith.science/pith/UX35GYOYX4M4NDRZI5JNBXPZHF/state.json","well_known_bundle":"https://pith.science/.well-known/pith/UX35GYOYX4M4NDRZI5JNBXPZHF/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2018:UX35GYOYX4M4NDRZI5JNBXPZHF","merge_version":"pith-open-graph-merge-v1","event_count":2,"valid_event_count":2,"invalid_event_count":0,"equivocation_count":0,"current":{"canonical_record":{"metadata":{"abstract_canon_sha256":"f809c4f68bced0745151fcb0cb030e030bca4d91b3a92899292f64fb9ce43680","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.HE","submitted_at":"2018-08-20T13:30:27Z","title_canon_sha256":"943f33abf2380174dabd983faed8e6b4e29392ad8428cffcb5bedfe9fecd715a"},"schema_version":"1.0","source":{"id":"1808.06442","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1808.06442","created_at":"2026-05-18T00:07:44Z"},{"alias_kind":"arxiv_version","alias_value":"1808.06442v1","created_at":"2026-05-18T00:07:44Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1808.06442","created_at":"2026-05-18T00:07:44Z"},{"alias_kind":"pith_short_12","alias_value":"UX35GYOYX4M4","created_at":"2026-05-18T12:32:56Z"},{"alias_kind":"pith_short_16","alias_value":"UX35GYOYX4M4NDRZ","created_at":"2026-05-18T12:32:56Z"},{"alias_kind":"pith_short_8","alias_value":"UX35GYOY","created_at":"2026-05-18T12:32:56Z"}],"graph_snapshots":[{"event_id":"sha256:e37e549c546d77cb33894ab855bccb69a3005ca9b220c7f6bdb1765874bab8bb","target":"graph","created_at":"2026-05-18T00:07:44Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"graph_snapshot":{"author_claims":{"count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","strong_count":0},"builder_version":"pith-number-builder-2026-05-17-v1","claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"paper":{"abstract_excerpt":"The Neutron Star Interior Composition Explorer (NICER) on the International Space Station (ISS) observed strong photospheric expansion of the neutron star in 4U 1820-30 during a Type I X-ray burst. A thermonuclear helium flash in the star's envelope powered a burst that reached the Eddington limit. Radiation pressure pushed the photosphere out to ~200 km, while the blackbody temperature dropped to 0.45 keV. Previous observations of similar bursts were performed with instruments that are sensitive only above 3 keV, and the burst signal was weak at low temperatures. NICER's 0.2-12 keV passband e","authors_text":"B. LaMarr, C. B. Markwardt, D. Chakrabarty, F. K. Lamb, G. K. Jaisawal, J. Chenevez, J. Homan, J. J. M. in 't Zand, K. C. Gendreau, L. Keek, S. Guillot, S. Mahmoodifar, T. E. Strohmayer, T. G\\\"uver, T. Okajima, Z. Arzoumanian","cross_cats":[],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.HE","submitted_at":"2018-08-20T13:30:27Z","title":"NICER Detection of Strong Photospheric Expansion during a Thermonuclear X-Ray Burst from 4U 1820-30"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1808.06442","kind":"arxiv","version":1},"verdict":{"created_at":null,"id":null,"model_set":{},"one_line_summary":"","pipeline_version":null,"pith_extraction_headline":"","strongest_claim":"","weakest_assumption":""}},"verdict_id":null}}],"author_attestations":[],"timestamp_anchors":[],"storage_attestations":[],"citation_signatures":[],"replication_records":[],"corrections":[],"mirror_hints":[],"record_created":{"event_id":"sha256:222261967301bd352355e867987192b3995a3486f3c857f4f6ca1cbcec29606a","target":"record","created_at":"2026-05-18T00:07:44Z","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":"f809c4f68bced0745151fcb0cb030e030bca4d91b3a92899292f64fb9ce43680","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.HE","submitted_at":"2018-08-20T13:30:27Z","title_canon_sha256":"943f33abf2380174dabd983faed8e6b4e29392ad8428cffcb5bedfe9fecd715a"},"schema_version":"1.0","source":{"id":"1808.06442","kind":"arxiv","version":1}},"canonical_sha256":"a5f7d361d8bf19c68e394752d0ddf939530daac8b0c96ecd08fb9ff045b99702","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"a5f7d361d8bf19c68e394752d0ddf939530daac8b0c96ecd08fb9ff045b99702","first_computed_at":"2026-05-18T00:07:44.900747Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T00:07:44.900747Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"ElvJl5UCLu6wqJkST3bW1nvrtVLVU1uD1p8vzbTqXpaguVDlurkzxFBUQkYcRgpVK9qL5t6DTN0GkwlyQdxxBg==","signature_status":"signed_v1","signed_at":"2026-05-18T00:07:44.901338Z","signed_message":"canonical_sha256_bytes"},"source_id":"1808.06442","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:222261967301bd352355e867987192b3995a3486f3c857f4f6ca1cbcec29606a","sha256:e37e549c546d77cb33894ab855bccb69a3005ca9b220c7f6bdb1765874bab8bb"],"state_sha256":"85f8a4e1bf5c4675bc74ca60aed6404d54f78f3db37e1d0cbac0d21792b28354"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"pc0iQgpk7P7QUTpXTrBvTCDjXnRPGJ6yqqKchZ+zXXMQdXmvb/lQVFIo6Cu4jzj6djnq8d4RD0rCkc9zY5yMCg==","signed_message":"bundle_sha256_bytes","signed_at":"2026-05-24T15:20:04.990975Z","bundle_sha256":"9d756971e837c851d800bd786fb257a82e84cb52d4e672901fcf3a7030091ec3"}}