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30 September 2004 Operational performance of OzPoz: the multifiber positioner on the VLT
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OzPoz is the multi-fiber positioner feeding the spectrographs GIRAFFE and UVES from a Nasmyth focus of VLT Unit Telescope 2. Together with GIRAFFE and UVES, it forms the FLAMES facility. FLAMES has been available for observing since successful completion of its science verification in Jan/Feb 2003. An aim of paramount importance in the design and construction of OzPoz was achievement of high reliability with minimal maintenance in the demanding Cerro Paranal VLT environment. Judged by its first 13 months of operation, it has been very successful in this respect, with an average of only 1% of observing time lost to problems; in the last 5 months of this period, the average was less than 0.1%. Of about 360 fibers and fiber bundles fed from deployable buttons on the two field plates, only one has become unusable (through breakage). The time taken to re-configure the fibers on one plate is always less than the exposure time (a minimum of 20 minutes) on the other (observing) plate, so no observing time is lost on that account and the time to interchange the two plates and acquire the new field is only about 5 minutes. The faintness of objects for which useful spectra can be obtained depends on the accuracy with which the sky background can be subtracted and this, in turn, depends on how well the relative spectral transmissions of fibers allocated to sky and to objects can be calibrated. An accuracy of 0.3% rms has been achieved.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Peter Gillingham, Jonathan Smoker, Matthew Colless, and Andreas Kaufer "Operational performance of OzPoz: the multifiber positioner on the VLT", Proc. SPIE 5492, Ground-based Instrumentation for Astronomy, (30 September 2004);


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