Probing 3D and NLTE models using APOGEE observations of globular cluster stars T. Masseron, Y. Osorio, D. A. García-Hernández, C. Allende Prieto, O. Zamora and Sz. Mészáros A&A, 647 (2021) A24 Published online: 03 March 2021 DOI: 10.1051/0004-6361/202039484