{"paper":{"title":"The methane distribution and polar brightening on Uranus based on HST/STIS, Keck/NIRC2, and IRTF/SpeX observations through 2015","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.EP","authors_text":"Erich Karkoschka, Heidi B. Hammel, Imke de Pater, Lawrence A. Sromovsky, Patrick M. Fry","submitted_at":"2018-06-04T15:01:18Z","abstract_excerpt":"HST/STIS observations of Uranus in 2015 show that the depletion of upper tropospheric methane has been relatively stable and that the polar region has been brightening over time as a result of increased aerosol scattering. This interpretation is confirmed by near-IR imaging from HST and from the Keck telescope using NIRC2 adaptive optics imaging. Our analysis of the 2015 spectra, as well as prior spectra from 2012, shows that there is a factor of three decrease in the effective upper tropospheric methane mixing ratio between 30\\deg N and 70\\deg N. The absolute value of the deep methane mixing "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1806.01154","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"}