{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2015:PKUWQXR7JPCHKBXWBVZQG6LVTQ","short_pith_number":"pith:PKUWQXR7","canonical_record":{"source":{"id":"1509.08393","kind":"arxiv","version":2},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2015-09-28T17:05:42Z","cross_cats_sorted":[],"title_canon_sha256":"53f584b5fed135e999e999690ac750c18e8423d37ec9a734d8e32657f5362077","abstract_canon_sha256":"49e9feb73164e3e63330656d4eb5559ccdc34c92e0b6982778d40fd74a8c909b"},"schema_version":"1.0"},"canonical_sha256":"7aa9685e3f4bc47506f60d730379759c3e8d951b63e8b26c3b378f111b43dadd","source":{"kind":"arxiv","id":"1509.08393","version":2},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1509.08393","created_at":"2026-05-18T01:22:14Z"},{"alias_kind":"arxiv_version","alias_value":"1509.08393v2","created_at":"2026-05-18T01:22:14Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1509.08393","created_at":"2026-05-18T01:22:14Z"},{"alias_kind":"pith_short_12","alias_value":"PKUWQXR7JPCH","created_at":"2026-05-18T12:29:37Z"},{"alias_kind":"pith_short_16","alias_value":"PKUWQXR7JPCHKBXW","created_at":"2026-05-18T12:29:37Z"},{"alias_kind":"pith_short_8","alias_value":"PKUWQXR7","created_at":"2026-05-18T12:29:37Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2015:PKUWQXR7JPCHKBXWBVZQG6LVTQ","target":"record","payload":{"canonical_record":{"source":{"id":"1509.08393","kind":"arxiv","version":2},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2015-09-28T17:05:42Z","cross_cats_sorted":[],"title_canon_sha256":"53f584b5fed135e999e999690ac750c18e8423d37ec9a734d8e32657f5362077","abstract_canon_sha256":"49e9feb73164e3e63330656d4eb5559ccdc34c92e0b6982778d40fd74a8c909b"},"schema_version":"1.0"},"canonical_sha256":"7aa9685e3f4bc47506f60d730379759c3e8d951b63e8b26c3b378f111b43dadd","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T01:22:14.133527Z","signature_b64":"CsEp50TNdqTg1Q3BQv+FOPGkeQwIVqcPmJtsYoMeV61h78iPK3WP664HEVXxej9KHOhYqRPJSD6zpG0c/rUXAw==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"7aa9685e3f4bc47506f60d730379759c3e8d951b63e8b26c3b378f111b43dadd","last_reissued_at":"2026-05-18T01:22:14.132756Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T01:22:14.132756Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1509.08393","source_version":2,"attestation_state":"computed"},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T01:22:14Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"2pmHddgUEaPYL3JhyhaY3mUVLMc6j7JJKGWpJZ6RehibGpbFG6Nzfh52aLLJS4DMUrGLBG8f1dHU+PdzJwhUCQ==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-06-07T17:42:23.869901Z"},"content_sha256":"e6d7cd2cdd834f3e69876fda393182f5b5e7fb1b9cf1d5357ad67ed851a858ad","schema_version":"1.0","event_id":"sha256:e6d7cd2cdd834f3e69876fda393182f5b5e7fb1b9cf1d5357ad67ed851a858ad"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2015:PKUWQXR7JPCHKBXWBVZQG6LVTQ","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"A Systematic Search for Changing-Look Quasars in SDSS","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.GA","authors_text":"Andy Lawrence, Chelsea L. MacLeod, Christopher Waters, Eugene Magnier, Heather Flewelling, Keith Horne, Ken C. Chambers, Klaus Hodapp, Mike Goad, Nicholas P. Ross, Nick Kaiser, Richard Wainscoat, William Burgett","submitted_at":"2015-09-28T17:05:42Z","abstract_excerpt":"We present a systematic search for changing-look quasars based on repeat photometry from SDSS and Pan-STARRS1, along with repeat spectra from SDSS and SDSS-III BOSS. Objects with large, |\\Delta g|>1 mag photometric variations in their light curves are selected as candidates to look for changes in broad emission line (BEL) features. Out of a sample of 1011 objects that satisfy our selection criteria and have more than one epoch of spectroscopy, we find 10 examples of quasars that have variable and/or \"changing-look\" BEL features. Four of our objects have emerging BELs; five have disappearing BE"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1509.08393","kind":"arxiv","version":2},"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":"2026-05-18T01:22:14Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"9O0oPiYRKvVhfqOI9Hx0wAikp6oNQG6x+YVJEM4gb0Zs04LAAyHukx3XyZ0UuIs/J7NPcGAagkFpUF9vYWtJBQ==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-06-07T17:42:23.870552Z"},"content_sha256":"8fb9df3c3609d49d28ffb7579b3e984aedce828e5aecb9346e283b89d7f90219","schema_version":"1.0","event_id":"sha256:8fb9df3c3609d49d28ffb7579b3e984aedce828e5aecb9346e283b89d7f90219"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/PKUWQXR7JPCHKBXWBVZQG6LVTQ/bundle.json","state_url":"https://pith.science/pith/PKUWQXR7JPCHKBXWBVZQG6LVTQ/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/PKUWQXR7JPCHKBXWBVZQG6LVTQ/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":"2026-06-07T17:42:23Z","links":{"resolver":"https://pith.science/pith/PKUWQXR7JPCHKBXWBVZQG6LVTQ","bundle":"https://pith.science/pith/PKUWQXR7JPCHKBXWBVZQG6LVTQ/bundle.json","state":"https://pith.science/pith/PKUWQXR7JPCHKBXWBVZQG6LVTQ/state.json","well_known_bundle":"https://pith.science/.well-known/pith/PKUWQXR7JPCHKBXWBVZQG6LVTQ/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2015:PKUWQXR7JPCHKBXWBVZQG6LVTQ","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":"49e9feb73164e3e63330656d4eb5559ccdc34c92e0b6982778d40fd74a8c909b","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2015-09-28T17:05:42Z","title_canon_sha256":"53f584b5fed135e999e999690ac750c18e8423d37ec9a734d8e32657f5362077"},"schema_version":"1.0","source":{"id":"1509.08393","kind":"arxiv","version":2}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1509.08393","created_at":"2026-05-18T01:22:14Z"},{"alias_kind":"arxiv_version","alias_value":"1509.08393v2","created_at":"2026-05-18T01:22:14Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1509.08393","created_at":"2026-05-18T01:22:14Z"},{"alias_kind":"pith_short_12","alias_value":"PKUWQXR7JPCH","created_at":"2026-05-18T12:29:37Z"},{"alias_kind":"pith_short_16","alias_value":"PKUWQXR7JPCHKBXW","created_at":"2026-05-18T12:29:37Z"},{"alias_kind":"pith_short_8","alias_value":"PKUWQXR7","created_at":"2026-05-18T12:29:37Z"}],"graph_snapshots":[{"event_id":"sha256:8fb9df3c3609d49d28ffb7579b3e984aedce828e5aecb9346e283b89d7f90219","target":"graph","created_at":"2026-05-18T01:22:14Z","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":"We present a systematic search for changing-look quasars based on repeat photometry from SDSS and Pan-STARRS1, along with repeat spectra from SDSS and SDSS-III BOSS. Objects with large, |\\Delta g|>1 mag photometric variations in their light curves are selected as candidates to look for changes in broad emission line (BEL) features. Out of a sample of 1011 objects that satisfy our selection criteria and have more than one epoch of spectroscopy, we find 10 examples of quasars that have variable and/or \"changing-look\" BEL features. Four of our objects have emerging BELs; five have disappearing BE","authors_text":"Andy Lawrence, Chelsea L. MacLeod, Christopher Waters, Eugene Magnier, Heather Flewelling, Keith Horne, Ken C. Chambers, Klaus Hodapp, Mike Goad, Nicholas P. Ross, Nick Kaiser, Richard Wainscoat, William Burgett","cross_cats":[],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2015-09-28T17:05:42Z","title":"A Systematic Search for Changing-Look Quasars in SDSS"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1509.08393","kind":"arxiv","version":2},"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:e6d7cd2cdd834f3e69876fda393182f5b5e7fb1b9cf1d5357ad67ed851a858ad","target":"record","created_at":"2026-05-18T01:22:14Z","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":"49e9feb73164e3e63330656d4eb5559ccdc34c92e0b6982778d40fd74a8c909b","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2015-09-28T17:05:42Z","title_canon_sha256":"53f584b5fed135e999e999690ac750c18e8423d37ec9a734d8e32657f5362077"},"schema_version":"1.0","source":{"id":"1509.08393","kind":"arxiv","version":2}},"canonical_sha256":"7aa9685e3f4bc47506f60d730379759c3e8d951b63e8b26c3b378f111b43dadd","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"7aa9685e3f4bc47506f60d730379759c3e8d951b63e8b26c3b378f111b43dadd","first_computed_at":"2026-05-18T01:22:14.132756Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T01:22:14.132756Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"CsEp50TNdqTg1Q3BQv+FOPGkeQwIVqcPmJtsYoMeV61h78iPK3WP664HEVXxej9KHOhYqRPJSD6zpG0c/rUXAw==","signature_status":"signed_v1","signed_at":"2026-05-18T01:22:14.133527Z","signed_message":"canonical_sha256_bytes"},"source_id":"1509.08393","source_kind":"arxiv","source_version":2}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:e6d7cd2cdd834f3e69876fda393182f5b5e7fb1b9cf1d5357ad67ed851a858ad","sha256:8fb9df3c3609d49d28ffb7579b3e984aedce828e5aecb9346e283b89d7f90219"],"state_sha256":"f3c8564522777549a98086217e2e511f6fd7e9e437847e92bb6fbb62c0673944"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"MDN8nJDkD2paJyA9HHisVy3FXuEVv5khTwyXwZBdRt0StdKML70vWX9ZJMgsObvDIfNOtVLqcuJ6M52XT1CbAg==","signed_message":"bundle_sha256_bytes","signed_at":"2026-06-07T17:42:23.874212Z","bundle_sha256":"3ec8f393dc96c365bdd365ccbdc9c491aa57276bc169ec91b54e6512ed5d0069"}}