AMOS S.A. is a small company specialised in the fields of opto-mechanical, thermal and vacuum technology. To develop, manufacture and test the ESO VLTI Auxiliary Telescope System (ATS) was considered internally as a big challenge. ATS is a large-sized project and difficult to manage for a small company (since ATS, AMOS has hired about 25 people and now employs about 60 people). ATS is also technically a very complex system because of the following reasons:
• Unusual telescope (mobile telescope)
• Very tight system performances (e.g. Image quality, OPD, Pointing)
• Severe design constraints because of existing site interfaces (e.g. volume, mass) and environment (including wind and earthquake)
• Multidisciplinary engineering system (mechanical, optical, electrical, thermal, pneumatic, hydraulic)
This paper describes how this project has been managed in practice by AMOS and also the important role of the system engineering. The last paragraph will be dedicated to the main lessons learned.