TITANS metal-poor reference stars - I. Accurate effective temperatures and surface gravities for dwarfs and subgiants from 3D non-LTE Hα profiles and Gaia parallaxesR. E. Giribaldi, A. R. da Silva, R. Smiljanic and D. Cornejo EspinozaA&A, 650 (2021) A194DOI: https://doi.org/10.1051/0004-6361/202140751