{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2018:HEYB64CQVWVIOJOV2XH563EFVL","short_pith_number":"pith:HEYB64CQ","canonical_record":{"source":{"id":"1804.07947","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.IM","submitted_at":"2018-04-21T11:19:07Z","cross_cats_sorted":[],"title_canon_sha256":"0a6fdbd8239204aa56ef2fb4cdc8a1d4c0aae132eff16a8407fb17cb4d6bb22f","abstract_canon_sha256":"eb7bcdae2f01799cfc036b7d71df778f877221169a2c0b0fc9d527ef30dbbddb"},"schema_version":"1.0"},"canonical_sha256":"39301f7050adaa8725d5d5cfdf6c85aac086d29838f6c665876dc1398243e4c7","source":{"kind":"arxiv","id":"1804.07947","version":1},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1804.07947","created_at":"2026-05-18T00:08:42Z"},{"alias_kind":"arxiv_version","alias_value":"1804.07947v1","created_at":"2026-05-18T00:08:42Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1804.07947","created_at":"2026-05-18T00:08:42Z"},{"alias_kind":"pith_short_12","alias_value":"HEYB64CQVWVI","created_at":"2026-05-18T12:32:28Z"},{"alias_kind":"pith_short_16","alias_value":"HEYB64CQVWVIOJOV","created_at":"2026-05-18T12:32:28Z"},{"alias_kind":"pith_short_8","alias_value":"HEYB64CQ","created_at":"2026-05-18T12:32:28Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2018:HEYB64CQVWVIOJOV2XH563EFVL","target":"record","payload":{"canonical_record":{"source":{"id":"1804.07947","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.IM","submitted_at":"2018-04-21T11:19:07Z","cross_cats_sorted":[],"title_canon_sha256":"0a6fdbd8239204aa56ef2fb4cdc8a1d4c0aae132eff16a8407fb17cb4d6bb22f","abstract_canon_sha256":"eb7bcdae2f01799cfc036b7d71df778f877221169a2c0b0fc9d527ef30dbbddb"},"schema_version":"1.0"},"canonical_sha256":"39301f7050adaa8725d5d5cfdf6c85aac086d29838f6c665876dc1398243e4c7","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T00:08:42.197499Z","signature_b64":"hlVgZCXpbuBb6YZVDA2FXeUbLlvscoC840nVOSEhmFSB+6omA2Dx2an/xQczk5IPnKxv3D8iZq5UtAh6l1MvCQ==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"39301f7050adaa8725d5d5cfdf6c85aac086d29838f6c665876dc1398243e4c7","last_reissued_at":"2026-05-18T00:08:42.196726Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T00:08:42.196726Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1804.07947","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":"2026-05-18T00:08:42Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"xDYhbWrnWYjBVgKLuUeUGSkhceWPP8zhry880dYNnvbiwy1lUFtbYnOkjUAok5K8k26cUiqBC3Ko9QwkekpWBw==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-20T11:21:54.062420Z"},"content_sha256":"59cf5ffe8e08ec949d586b761335a58f66c4ae3218f1ad6b536594d529cc8e70","schema_version":"1.0","event_id":"sha256:59cf5ffe8e08ec949d586b761335a58f66c4ae3218f1ad6b536594d529cc8e70"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2018:HEYB64CQVWVIOJOV2XH563EFVL","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"The effect of the ionosphere on ultra-low frequency radio-interferometric observations","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.IM","authors_text":"D.A. Rafferty, F. De Gasperin, H.T. Intema, M. Mevius, R.A. Fallows","submitted_at":"2018-04-21T11:19:07Z","abstract_excerpt":"The ionosphere is the main driver of a series of systematic effects that limit our ability to explore the low frequency (<1 GHz) sky with radio interferometers. Its effects become increasingly important towards lower frequencies and are particularly hard to calibrate in the low signal-to-noise ratio regime in which low-frequency telescopes operate. In this paper we characterize and quantify the effect of ionospheric-induced systematic errors on astronomical interferometric radio observations at ultra-low frequencies (<100 MHz). We also provide guidelines for observations and data reduction at "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1804.07947","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":"2026-05-18T00:08:42Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"W7Vm41VOYQIzFGywGIFDtEXpzPbUp6Tc9V68kY5lq82WgQbKorzGpbvNnBnn7se1VxmxMoXsHRYQRzo8cHatAQ==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-20T11:21:54.062762Z"},"content_sha256":"0c3040dfaa4656b02d041ed5de70f0aa039af1e75c703841528f4bf00103fca4","schema_version":"1.0","event_id":"sha256:0c3040dfaa4656b02d041ed5de70f0aa039af1e75c703841528f4bf00103fca4"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/HEYB64CQVWVIOJOV2XH563EFVL/bundle.json","state_url":"https://pith.science/pith/HEYB64CQVWVIOJOV2XH563EFVL/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/HEYB64CQVWVIOJOV2XH563EFVL/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":"2026-05-20T11:21:54Z","links":{"resolver":"https://pith.science/pith/HEYB64CQVWVIOJOV2XH563EFVL","bundle":"https://pith.science/pith/HEYB64CQVWVIOJOV2XH563EFVL/bundle.json","state":"https://pith.science/pith/HEYB64CQVWVIOJOV2XH563EFVL/state.json","well_known_bundle":"https://pith.science/.well-known/pith/HEYB64CQVWVIOJOV2XH563EFVL/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2018:HEYB64CQVWVIOJOV2XH563EFVL","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":"eb7bcdae2f01799cfc036b7d71df778f877221169a2c0b0fc9d527ef30dbbddb","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.IM","submitted_at":"2018-04-21T11:19:07Z","title_canon_sha256":"0a6fdbd8239204aa56ef2fb4cdc8a1d4c0aae132eff16a8407fb17cb4d6bb22f"},"schema_version":"1.0","source":{"id":"1804.07947","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1804.07947","created_at":"2026-05-18T00:08:42Z"},{"alias_kind":"arxiv_version","alias_value":"1804.07947v1","created_at":"2026-05-18T00:08:42Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1804.07947","created_at":"2026-05-18T00:08:42Z"},{"alias_kind":"pith_short_12","alias_value":"HEYB64CQVWVI","created_at":"2026-05-18T12:32:28Z"},{"alias_kind":"pith_short_16","alias_value":"HEYB64CQVWVIOJOV","created_at":"2026-05-18T12:32:28Z"},{"alias_kind":"pith_short_8","alias_value":"HEYB64CQ","created_at":"2026-05-18T12:32:28Z"}],"graph_snapshots":[{"event_id":"sha256:0c3040dfaa4656b02d041ed5de70f0aa039af1e75c703841528f4bf00103fca4","target":"graph","created_at":"2026-05-18T00:08:42Z","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 ionosphere is the main driver of a series of systematic effects that limit our ability to explore the low frequency (<1 GHz) sky with radio interferometers. Its effects become increasingly important towards lower frequencies and are particularly hard to calibrate in the low signal-to-noise ratio regime in which low-frequency telescopes operate. In this paper we characterize and quantify the effect of ionospheric-induced systematic errors on astronomical interferometric radio observations at ultra-low frequencies (<100 MHz). We also provide guidelines for observations and data reduction at ","authors_text":"D.A. Rafferty, F. De Gasperin, H.T. Intema, M. Mevius, R.A. Fallows","cross_cats":[],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.IM","submitted_at":"2018-04-21T11:19:07Z","title":"The effect of the ionosphere on ultra-low frequency radio-interferometric observations"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1804.07947","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":"sha256:59cf5ffe8e08ec949d586b761335a58f66c4ae3218f1ad6b536594d529cc8e70","target":"record","created_at":"2026-05-18T00:08:42Z","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":"eb7bcdae2f01799cfc036b7d71df778f877221169a2c0b0fc9d527ef30dbbddb","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.IM","submitted_at":"2018-04-21T11:19:07Z","title_canon_sha256":"0a6fdbd8239204aa56ef2fb4cdc8a1d4c0aae132eff16a8407fb17cb4d6bb22f"},"schema_version":"1.0","source":{"id":"1804.07947","kind":"arxiv","version":1}},"canonical_sha256":"39301f7050adaa8725d5d5cfdf6c85aac086d29838f6c665876dc1398243e4c7","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"39301f7050adaa8725d5d5cfdf6c85aac086d29838f6c665876dc1398243e4c7","first_computed_at":"2026-05-18T00:08:42.196726Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T00:08:42.196726Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"hlVgZCXpbuBb6YZVDA2FXeUbLlvscoC840nVOSEhmFSB+6omA2Dx2an/xQczk5IPnKxv3D8iZq5UtAh6l1MvCQ==","signature_status":"signed_v1","signed_at":"2026-05-18T00:08:42.197499Z","signed_message":"canonical_sha256_bytes"},"source_id":"1804.07947","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:59cf5ffe8e08ec949d586b761335a58f66c4ae3218f1ad6b536594d529cc8e70","sha256:0c3040dfaa4656b02d041ed5de70f0aa039af1e75c703841528f4bf00103fca4"],"state_sha256":"c6bc080d7896ebf7665ade3551da9d752fbb34897575564ce63c29adec955024"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"6BCEw2x4o9tex/CagekN3rUu5/E50v41O8mHO9pq9s4d0NcSeSs6DFAPWTd8PtOqmtE6RByQGAUCsn1LaoFNCg==","signed_message":"bundle_sha256_bytes","signed_at":"2026-05-20T11:21:54.064600Z","bundle_sha256":"d9537f0ea90d1ae3e6fb7020ce6b7661450ba3429a0a9866ba217f4946140ffd"}}