Improved GRAVITY astrometric accuracy from modeling optical aberrations GRAVITY Collaboration, R. Abuter, A. Amorim, M. Bauböck, J. P. Berger, H. Bonnet, W. Brandner, Y. Clénet, R. Davies, P. T. de Zeeuw et al. (53 more) A&A, 647 (2021) A59 Published online: 09 March 2021 DOI: 10.1051/0004-6361/202040208