The Multi-Object Optical and Near-infrared Spectrograph (MOONS) will cover the Very Large Telescope's (VLT) field of view with 1000 fibres. The fibres will be mounted on fibre positioning units (FPU) implemented as two-DOF robot arms to ensure a homogeneous coverage of the 500 square arcmin field of view. To accurately and fast determine the position of the 1000 fibres a metrology system has been designed. This paper presents the hardware and software design and performance of the metrology system. The metrology system is based on the analysis of images taken by a circular array of 12 cameras located close to the VLTs derotator ring around the Nasmyth focus. The system includes 24 individually adjustable lamps. The fibre positions are measured through dedicated metrology targets mounted on top of the FPUs and fiducial markers connected to the FPU support plate which are imaged at the same time. A flexible pipeline based on VLT standards is used to process the images. The position accuracy was determined to ~5 μm in the central region of the images. Including the outer regions the overall positioning accuracy is ~25 μm. The MOONS metrology system is fully set up with a working prototype. The results in parts of the images are already excellent. By using upcoming hardware and improving the calibration it is expected to fulfil the accuracy requirement over the complete field of view for all metrology cameras.
FIDEOS (FIbre Dual Echelle Optical Spectrograph) is a fibre-fed bench-mounted high-resolution echelle spec- trograph for the 1-m telescope at ESO in La Silla, Chile. It is based on a 44.41 lines/mm 70° blaze angle
echelle grating in quasi-Littrow mode, providing spectral resolution of R ~ 42 000, covering the spectral range from 400 nm to 680 nm. The detector is a 2k×2k CCD with 15 μm pixels. The spectrograph will be fed by two 50
µm core diameter fibres for the astronomical object and the simultaneous calibration lamp, respectively. Alter- natively, an iodine cell will be mounted on the telescope-spectrograph interface, providing a secondary spectral calibration source. In addition, the instrument will be mounted on a fixed optical-bench without movable parts rather than the CCD shutter and its enclosure will be thermally controlled to ensure opto-mechanical stability. Since the FIDEOS will deliver high resolution and spectral stability, it will be optimized for precision radial velocities.