Newsletter 12 (2000) 05-09
6dF is the fully automated, pick-place, magnetic button fibre positioning system being built for the UK Schmidt Telescope (UKST) at the Anglo-Australian Observatory (AAO). This facility will offer the capability for full hemisphere spectroscopic surveys at the UKST. The WFAU and IfA are at the forefront in the scientific exploitation of this new instrument and the WFAU will also be a principal repository for the resultant data products.
6dF is an AAO project to create an automated fibre positioner and multi-object spectroscopic observing facility for the UKST. The positioner (Figure 1), like the FLAIR system that it replaces (and unlike 2dF) operates off telescope in a special dome enclosure. The facility offers:
The 6dF galaxy redshift survey is a competitive whole southern sky redshift/peculiar velocity survey based on NIR selection from 2MASS/DENIS data. These unique survey aspects were the prime reason 6dF was approved. Up to 75% of UKST time has been allocated to the survey. An example of what a cleaned 6dF image frame of 150 galaxy spectra would look like is shown in Figure 3 with typical equivalent FLAIR galaxy spectra (B=<17.1) are shown in Figure 4. The 6dF redshift survey is for a 2.17 µm K-band (K < 13) selected galaxy sample from the 2MASS Extended Source Catalogue (XSC) with star/galaxy separation checked against the higher resolution DENIS I-band imaging. The K-band is most closely related to the old stellar population luminosity and hence total galaxy mass whilst minimising both internal and external extinction. It is an excellent choice for a complete redshift survey and is unbiased wrt star formation. 90,000 redshifts will be obtained over 15,000deg2 over a 2-2.5 year period with completion by mid 2003. The photometric properties of a subset of the K-limited target sample are given in Figure 5 in relation to both J-K, B-K and R (figure courtesy of Matthew Colless, MSSSO). The primary goal of the second phase of the 6dF survey is to measure peculiar velocities over the entire southern sky. 2MASS and DENIS photometry will be combined with the observed velocity dispersions for a subset of 15,000 early type galaxies with V=<15,000Km/s to obtain Dn-sigma distances. This phase should be complete by 2004/2005. Both survey components will be non-proprietorial and 6dF will also operate as a common user instrument on the UKST. The pipeline data reduction software will be based on the AAT's 2dfdr reduction package to which the 6dF system is directly analogous. A Science Advisory Group (6dFSAG) has been set-up by the AAT board to provide scientific leadership and direction for the survey, to advise the board of progress and to formulate a detailed implementation plan for the redshift survey. The 6dFSAG membership comprises the two authors of this article plus Matthew Colless (chair), Gary Mamon (IaP), John Lucy (Durham), Elaine Sadler (Sydney), Ofer Lahav (IoA), John Huchra (CfA) and Will Saunders (IfA/AAO). Their contributions are gratefully acknowledged.
The AAO has prime responsibility to build and manage 6dF, integrate components, deliver configuration and positioning software, undertake commissioning and provide basic support for the facility once in operation as well as the day to day operational maintenance, repairs and upgrades. Apart from keen scientific interest the WFAU and IfA have a crucial role in the support of the prime 6dF redshift survey and resulting data products. The WFAU involvement includes:
Although for the first few years 6dF will concentrate on the main galaxy redshift survey the system is nevertheless a common user facility with 50-60 nights reserved for non-survey projects. Furthermore, once the main 6dF survey is complete, there is ample scope for alternative large-scale survey projects. For source densities of 5-50 per deg2 and magnitudes B =<19, 6dF is at least as fast as any current telescope and is likely to remain competitive for some time. A few possible types of project include:
Further details, latest news and information concerning 6dF including
commissioning and observing opportunities can be found
on the www at:
http://www.roe.ac.uk/ukstu/6df.html
), 2000-04-07