VLT(I) instrument operations and maintenance at the Paranal Observatory

The European Southern Observatory (ESO) operates its Very Large Telescope (VLT) on Cerro Paranal (Chile) with to date 11 scientific instruments including two interferometric instruments and their numerous auxiliary systems at 4 Unit Telescopes (UTs) and 3 Auxiliary Telescopes (ATs). The rigorous application of preventive and corrective maintenance procedures and a close monitoring of the instruments' engineering data streams are the key ingredient towards the minimization of the technical downtime of the instruments. The extensive use of standardized hardware and software components and their strict configuration control is considered crucial to efficiently manage the large number of systems with the limited human and technical resources available. A close collaboration between the instrument engineers, the instrument scientists in instrument operation teams (IOTs) turns out to be vital to maintain and to the performance of the instrumentation suite. In this paper, the necessary tools, workflows, and organizational structures to achieve these objectives are presented.