X-shooter, UV- to K band, intermediate resolution, high efficiency spectrograph for the VLT status report at the final design review

X-shooter is a single target spectrograph for the Cassegrain focus of one of the VLT UTs where it will start to operate in 2008. The instrument covers in a single exposure the spectral range from the UV to the K' band. It is designed to maximize the sensitivity in this spectral range through the splitting in three arms with optimized optics, coatings, dispersive elements and detectors. It operates at intermediate resolutions (R=4000-14000, depending on wavelength and slit width) with fixed echelle spectral format (with prism cross-dispersers) in the three arms. The project has completed the Final Design Review in June 2006. In this status report, the overall concept is summarized and new results on the dichroics, the active flexure compensation system, the operation modes and the expected performance are given. The instrument is being built by a Consortium of Institutes from Denmark, France, Italy and the Netherlands in collaboration with ESO. When in operation, its wide spectral range observing capability will be unique at very large telescopes.