Preparation for VLT software commissioning at Paranal

The very large telescope (VLT) software commissioning has started since a while, earlier than any VLT subsystems were ready for integration. This was possible thanks to the new technology telescope (NTT) upgrade (reported in a separate paper, Ref. 3), which shares most of the software with the VLT. The integration tests with the main VLT structure do also represent another fundamental milestone in the software commissioning process (see also separate paper, Ref. 4). The whole control software is based on a very distributed computer architecture. The final layout of the computers (work-stations and microprocessors), networking devices and underlying concepts have been tested both at the NTT and on the so called VLT computer control model, a relevant off-line subset of the computer equipment to be used in the VLT control room and telescope area for one unit telescope. The VLT common software including a real-time database, is the stable core of the whole VLT control software. This comprises also high level applications, like the real-time display (RTD), the panel editor and the CCD software to be used for technical CCDs. It is distributed with a policy of regular releases, subject to automatic regression tests and is used by VLT Consortia and contractors too. New modules have been added to insert the VLT control software in the data flow context, interfacing it in particular to schedular and archive. The VLT software support team will soon start regular operation at the VLT Paranal site, providing continuity between the integration activities of the various subsystems. They will be the front-end of the commissioning effort, based also on background support provided over links from the European headquarters.