The global sphere reconstruction (GSR) - Demonstrating an independent implementation of the astrometric core solution for GaiaA. Vecchiato, B. Bucciarelli, M. G. Lattanzi, U. Becciani, L. Bianchi, U. Abbas, E. Sciacca, R. Messineo and R. De MarchA&A, 620 (2018) A40DOI: https://doi.org/10.1051/0004-6361/201833254
