Developments in fiber-positioning technology for the WEAVE instrument at the William Herschel Telescope

WEAVEis the next-generation wide-field optical spectroscopy facility for the William Herschel Telescope(WHT) on La Palma in the Canary Islands, Spain. It is a multi-object "pick-and-place" fibre-fed spectrograph with a 1000 fibre multiplex behind a new dedicated 2° prime focus corrector. The WEAVEpositioner concept uses two robots working in tandem in order to reconfigure a fully populated field within the expected 1 hour dwell-timefor the instrument (a good match between the required exposure times and the limit of validity for a given configuration due to the effects of differential refraction). In this paper we describe some of the final design decisions arising from the prototyping phase of the instrument design and provide an update on the current manufacturing status of the fibre positioner system.