TY - JOUR Y1 - 2024/05// N2 - We report the disco v ery of a brown dwarf orbiting a M1 host star. We first identified the brown dwarf within the Next Generation Transit Surv e y data, with supporting observations found in TESS sectors 11 and 38. We confirmed the disco v ery with follow- up photometry from the South African Astronomical Observatory, SPECULOOS-S, and TRAPPIST-S, and radial velocity measurements from HARPS, which allowed us to characterize the system. We find an orbital period of ?1.25 d, a mass of 69 . 0 + 5 . 3 -4 . 8 M J , close to the hydrogen burning limit, and a radius of 0.95 ±0.05 R J . We determine the age to be > 0.5 Gyr, using model isochrones, which is found to be in agreement with spectral energy distribution fitting within errors. NGTS-28Ab is one of the shortest period systems found within the brown dwarf desert, as well as one of the highest mass brown dwarfs that transits an M dwarf. This makes NGTS-28Ab another important disco v ery within this scarcely populated region. ID - discovery10191948 UR - http://dx.doi.org/10.1093/mnras/stae508 VL - 530 SP - 318 JF - Monthly Notices of the Royal Astronomical Society PB - OXFORD UNIV PRESS A1 - Henderson, Beth A A1 - Casewell, Sarah L A1 - Goad, Michael R A1 - Acton, Jack S A1 - Guenther, Maximilian N A1 - Nielsen, Louise D A1 - Burleigh, Matthew R A1 - Belardi, Claudia A1 - Tilbrook, Rosanna H A1 - Turner, Oliver A1 - Howell, Steve B A1 - Clark, Catherine A A1 - Littlefield, Colin A1 - Barkaoui, Khalid A1 - Alves, Douglas R A1 - Anderson, David R A1 - Bayliss, Daniel A1 - Bouchy, Francois A1 - Bryant, Edward M A1 - Dransfield, George A1 - Ducrot, Elsa A1 - Eigmueller, Philipp A1 - Gill, Samuel A1 - Gillen, Edward A1 - Gillon, Michael A1 - Hawthorn, Faith A1 - Hooton, Matthew J A1 - Jackman, James AG A1 - Jehin, Emmanuel A1 - Jenkins, James S A1 - Kendall, Alicia A1 - Lendl, Monika A1 - Mccormac, James A1 - Moyano, Maximiliano A1 - Pedersen, Peter Pihlmann A1 - Pozuelos, Francisco J A1 - Ramsay, Gavin A1 - Sefako, Ramotholo R A1 - Timmermans, Mathilde A1 - Triaud, Amaury HMJ A1 - Udry, Stephane A1 - Vines, Jose A1 - Watson, Christopher A A1 - West, Richard G A1 - Wheatley, Peter J A1 - Zuniga-Fernandez, Sebastian TI - NGTS-28Ab: a short period transiting brown dwarf SN - 0035-8711 AV - public IS - 1 EP - 339 N1 - © 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. KW - (stars:) brown dwarfs ER -