A wide range of European operated telescopes at different locations are offering observing time to external users through the OPTICON Trans-national Access Programme. This project was supported for the period 2004-2008 by the European Commission under the Sixth Framework Programme (FP6).

From 2009 onwards this Transnational Access Programme is supported by the European Commission under the Seventh Framework Programme (FP7) (Period 2009-2012).