6df: An Automated Multi-Object Fibre Spectroscopy System for the UKST

Abstract

Apart from carrying out wide-field photographic imaging the U.K. Schmidt Telescope of the Anglo-Australian Observatory also operates the FLAIR multi-fibre spectroscopy system (e.g. Parker and Watson 1995). In the five years in which FLAIR has operated as a common-user facility, over 22 000 object spectra have been obtained. However, a major drawback of the current system is that the fibre positioning is only semi-automated and can take four to six hours to affix the 100 fibres over the UKST field. With a thinned CCD being commissioned in 1995 typical observations of sufficient S/N now take much less than this (e.g. about an hour for galaxy redshifts to B 17). Clearly FLAIR is operating far short of its potential. Consequently a fully-automated, off telescope, pick-place fibre-positioning system known as 6dF has been proposed to address this bottle-neck. The aim is to provide a system capable of configuring 150 fibres in under an hour across a 6-degree circular field. Three field plates are also planned allowing rapid field interchange (10-15 minute field plate changeover expected) to keep up with the observations. A factor 10 improvement in observing efficiency is promised. For the first time, an effective means of tackling major, full hemisphere, spectroscopic surveys will be available at the UKST. An all southern sky near-infrared selected galaxy redshift survey is a specific high-priority example. We have just completed a phase-A design study where many of the concepts have been successfully tested. The estimated cost of 6dF is $A450k with some funding already in place. The instrument will be built over a timescale of 2 years with expected commissioning in early 2000.