Autofib-2: commissioning results of a robotic multiobject fiber system for the William Herschel Telescope

摘要

Autofib-2 is a robotic fiber system for the prime focus of the William Herschel telescope capable of placing up to 150 fibers in the 1 degree focal plane of the telescope. The fibers are fed to a purpose built spectrograph (WYFFOS) mounted on one of the Nasmyth platforms. Autofib-2 and WYFFOS are now entering a common user phase as fully commissioned instruments. We describe the novel techniques used to achieve the high precision in fiber placement delivered by this instrument and the quality control procedures devised to measure and monitor instrument stability. The characterization of the distortions of focal plane delivered by the prime focus corrector of the telescope was a vital procedure during the commissioning. We describe the methods of measuring these distortions and discuss the limitations of the instrument, telescope and astrometry.