Some new techniques in automated multiple-object fibre spectroscopy

Multiple-object fibre optic spectroscopy has for several years enabled extensive spectroscopic surveys of faint astronomical objects to be made. In the near future, large fields of view will become available at the prime foci of two UK telescopes, the William Herschel Telescope and the Anglo-Australian Telescope. Multiple fibre spectroscopy is ideally suited to cover the large fields of view soon to be available at prime focus. In order to apply the technique of multiple fibre spectroscopy to these prime foci, the current technology used in automatic fibre positioners must be improved upon. As part of this work, a full working instrument has been built to investigate the operational problems associated with an instrument working at prime focus. The technical results from two commissioning runs, and some examples of astronomical results are presented. This work also describes the development of robotic techniques that will enable the simultaneous use of up to 400 fibres, each located to an accuracy of better than 10 µm rms. This is easily within the tolerance required by the plate scale of the prime focus correctors planned for each telescope.