Published online by Cambridge University Press: 15 February 2011
Testing instrument capabilities is a crucial issue for Gaia, where high levelperformances are expected. This activity involves many aspects: simulation of theinstrument through suitable modelling, comparison of the models with the actualinstrument, as well as producing evaluation methods, which are strictly related to the waydata will be processed and calibrated. In this paper I discuss the interconnections amongthese aspects, and provide some example from the current testing activities.