Buder, SvenSharma, SanjibKos, J.Amarsi, A. M.Nordlander, ThomasLind, KarinMartell, S. L.Asplund, MartinBland-Hawthorn, JonathanCasey, AndrewDe Silva, Gayandhi MD’Orazi, ValentinaFreeman, KennethHayden, Michael R.Lewis, Geraint Francislin, janeSchlesinger, KatharineSimpson, Jeffrey DStello, DennisZucker, DanielCasagrande, LucaDa Costa, GaryNandakumar, GovindTing, Yuan-SenZerjal, Marusa2026-01-272026-01-270035-8711https://hdl.handle.net/1885/733804969The ensemble of chemical element abundance measurements for stars, along with precision distances and orbit properties, provides high-dimensional data to study the evolution of the Milky Way. With this third data release of the Galactic Archaeology with HERMES (GALAH) survey, we publish 678 423 spectra for 588 571 mostly nearby stars (81.2 per cent of stars are within <2 kpc), observed with the HERMES spectrograph at the Anglo-Australian Telescope. This release (hereafter GALAH+ DR3) includes all observations from GALAH Phase 1 (bright, main, and faint survey, 70 per cent), K2-HERMES (17 per cent), TESS-HERMES (5 per cent), and a subset of ancillary observations (8 per cent) including the bulge and >75 stellar clusters. We derive stellar parameters T-eff, logg, [Fe/H], v(mic), v(broad), and v(rad) using our modified version of the spectrum synthesis code Spectroscopy Made Easy (SME) and 1D MARCS model atmospheres. We break spectroscopic degeneracies in our spectrum analysis with astrometry from Gaia DR2 and photometry from 2MASS. We report abundance ratios [X/Fe] for 30 different elements (11 of which are based on non-LTE computations) covering five nucleosynthetic pathways. We describe validations for accuracy and precision, flagging of peculiar stars/measurements and recommendations for using our results. Our catalogue comprises 65 per cent dwarfs, 34 per cent giants, and 1 per cent other/unclassified stars. Based on unflagged chemical composition and age, we find 62 per cent young low-alpha, 9 per cent young high-alpha, 27 per cent old high-alpha, and 2 per cent stars with [Fe/H] <= -1. Based on kinematics, 4 per cent are halo stars. Several Value-Added-Catalogues, including stellar ages and dynamics, updated after Gaia eDR3, accompany this release and allow chrono-chemodynamic analyses, as we showcase.SB and KL acknowledge funds from the Alexander von Humboldt Foundation in the framework of the Sofja Kovalevskaja Award endowed by the Federal Ministry of Education and Research. SB acknowledges travel support from Universities Australia and Deutsche Akademische Austauschdienst. JK and TZ acknowledge financial support of the Slovenian Research Agency (research core funding No. P1-0188) and the European Space Agency (PRODEX Experiment Arrangement No. C4000127986). AMA acknowledges support from the Swedish Research Council (VR 2016-03765), and the project grants ‘The New Milky Way’ (KAW 2013.0052) and ‘Probing charge- and mass-transfer reactions on the atomic level’ (KAW 2018.0028) from the Knut and Alice Wallenberg Foundation. KL acknowledges funds from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 852977). KCF acknowledges support from the Australian Research Council under award number DP160103747. LS acknowledges financial support from the Australian Research Council (Discovery Project 170100521) and from the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. CK acknowledges funding from the UK Science and Technology Facility Council (STFC) through grant ST/ R000905/1, and the Stromlo Distinguished Visitorship at the ANU. DMN acknowledges support from NASA under award Number 80NSSC19K0589, and support from the Allan C. And Dorothy H. Davis Fellowship. YST is supported by the NASA Hubble Fellowship grant HST-HF2-51425 awarded by the Space Telescope Science Institute. GT was supported by the project grant ‘The New Milky Way’ from the Knut and Alice Wallenberg foundation and by the grant 2016-03412 from the Swedish Research Council. GT acknowledges financial support of the Slovenian Research Agency (research core funding No. P1-0188 and project N1-0040). MŽ acknowledges funding from the Australian Research Council (grant DP170102233).application/pdfen-AU© 2021 The Author(s)202110.1093/mnras/stab12422023-10-22