{"paper":{"title":"Correlation Between Energy Spectral States and Fast Time Variability and Further Evidence for the Marginally Stable Orbit in 4U 1820-30","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"A. P. Smale T. E. Strohmayer, J. H. Swank (Goddard Space Flight Center), W. Zhang","submitted_at":"1998-04-22T18:40:43Z","abstract_excerpt":"We report results from a long-term monitoring data set obtained with the Rossi X-ray Timing Explorer (RXTE) from the bright globular cluster binary source 4U 1820-30. During this monitoring, the source intensity varied from a flux of 2.9E-9 ergs/cm**2/s to 8.5E-9 ergs/cm**2/s in the 2-10 keV band, which correspond to, respectively, a count rate of 1,600 cps and 4,500 cps in the nominal 2-60 keV RXTE-PCA band. Its energy spectral state was observed to encompass both the banana branches and the island state. Kilohertz QPOs were observed to exist in the upper-banana and lower-banana branches, as "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/9804228","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/astro-ph/9804228/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"}