Optimization of synthetic galaxy spectra - Application to ESA’s Gaia mission A. Karampelas, M. Kontizas, B. Rocca-Volmerange, I. Bellas-Velidis, E. Kontizas, E. Livanou, P. Tsalmantza and A. Dapergolas A&A, 538 (2012) A38 Published online: 30 January 2012 DOI: 10.1051/0004-6361/201117872