{"paper":{"title":"The HST/WFC3 Transmission Spectrum of AU Mic b Part I: An Atmosphere Obscured by Contamination and Systematics","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":["astro-ph.SR"],"primary_cat":"astro-ph.EP","authors_text":"Andrew W. Mann, Brett M. Morris, Elisabeth Newton, Eric D. Lopez, Hannah R. Wakeford, Lili Alderson, Natasha E. Batalha, Patrick J. Lowrance, Peter Gao, Peter Plavchan, Roxana Lupu, William C. Waalkes, Zachory K. Berta-Thompson","submitted_at":"2026-06-30T07:55:25Z","abstract_excerpt":"Young sub-Neptune progenitors around M dwarfs offer an excellent opportunity to probe the formation of their abundant, older cousins. At $\\sim$20 Myr and only 9.7 pc away, AU Mic b is an ideal candidate for this effort, with its density and observations of escaping hydrogen pointing to a significant primordial atmosphere. Here we present the 0.8-1.6 $\\micron$ transmission spectrum of AU Mic b observed with the Wide Field Camera 3 on the Hubble Space Telescope (HST). We find that HST experienced unstable scanning during its visits, resulting in a variable PSF that dramatically affects the orbit"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2606.31281","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/2606.31281/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"}