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| 2dF fibre positioner | |
|---|---|
| Name | 2dF fibre positioner |
| Type | Fibre-optic multi-object spectrograph positioner |
| Introduced | 1997 |
| Place | Australia |
| Related | Anglo-Australian Telescope, Two-degree Field Galaxy Redshift Survey |
2dF fibre positioner
The 2dF fibre positioner is a robotic fibre-optic positioning system built for the Anglo-Australian Telescope to feed the Two-degree Field multi-object spectrograph used in large-scale spectroscopic surveys such as the Two-degree Field Galaxy Redshift Survey and the 2dF QSO Redshift Survey. It enabled simultaneous spectroscopy of hundreds of targets across a two-degree field of view, supporting projects led by institutions like the Anglo-Australian Observatory and collaborations including researchers from the University of Cambridge, University of Oxford, and the Australian National University. The instrument played a key role in cosmological investigations related to the Large-Scale Structure of the Universe and measurements of the Hubble constant via redshift surveys.
The 2dF fibre positioner is mounted at the prime focus of the Anglo-Australian Telescope and was delivered as part of a program coordinated by the Anglo-Australian Observatory with contributions from teams at the Royal Greenwich Observatory and the University of Oxford instrumentation groups. It supported up to 400 science fibres plus guide fibres on a field matching the Two-degree Field prime focus corrector, enabling spectroscopic campaigns like the Two-degree Field Galaxy Redshift Survey that significantly informed debates led by researchers at the Institute of Astronomy, Cambridge and the Sloan Digital Sky Survey-era programs. The system interfaces to the spectrographs where detectors such as CCDs produced spectra used in analyses by scientists at the European Southern Observatory and other major observatories.
Mechanical and optical design drew on prior instrument work at institutions such as the Royal Observatory, Edinburgh and the Cavendish Laboratory instrumentation groups. The core is a robotic gantry carrying 400 independently actuated fibre buttons arranged on a curved field plate corresponding to the Prime focus focal surface. Each fibre terminates in a polished button and is back-terminated to permit automated exchange and mapping, a method influenced by fibre systems developed at the Anglo-Australian Observatory and engineering groups at the University of Durham and MIT. The positioner works with a prime focus corrector designed in collaboration with optical groups from the University of Oxford and uses guide fibres monitored by cameras derived from detector readout designs employed at the European Southern Observatory and the Space Telescope Science Institute. Control electronics and software incorporated real-time control concepts similar to systems from the Jet Propulsion Laboratory and embedded-control expertise from the Rutherford Appleton Laboratory.
Operational procedures were established by staff at the Anglo-Australian Observatory and astronomers from surveys such as the Two-degree Field Galaxy Redshift Survey and the 2dF QSO Redshift Survey. Target coordinates from catalogues compiled by teams at the Sloan Digital Sky Survey, the Guide Star Catalog, and the Automated Plate Measuring facility feed the coordinate transformation routines developed with algorithms from the Cambridge University Engineering Department and matched to astrometric reference frames maintained by the US Naval Observatory. Fibre allocation and collision-avoidance routines were derived from optimization techniques used at the European Southern Observatory and were executed by control software running on workstations like those from Sun Microsystems and DEC. Calibration sequences use arc lamps and flat fields with detectors similar to those in projects at the Max Planck Institute for Astronomy to produce wavelength solutions and throughput maps applied in pipelines created by teams at the Anglo-Australian Observatory and data-reduction groups at the University of Cambridge.
At commissioning, the positioner achieved typical placement accuracy comparable with requirements from surveys such as the Two-degree Field Galaxy Redshift Survey, enabling fibre placement to within a few tenths of an arcsecond across the two-degree field. Repeatability, throughput uniformity, and field configuration times were adequate for nightly survey operations similar to those of the Sloan Digital Sky Survey but faced limits set by mechanical collision constraints, fibre bend radii, and atmospheric refraction effects studied by groups at the Royal Observatory, Edinburgh and the Australian National University. Limitations included configuration reconfiguration time compared to newer systems like the Sloan Digital Sky Survey cartridge changes, and the finite number of fibres compared with later instruments developed by teams at the European Southern Observatory and Gemini Observatory.
The 2dF fibre positioner enabled major surveys: the Two-degree Field Galaxy Redshift Survey and the 2dF QSO Redshift Survey, which produced large redshift catalogues exploited by cosmologists at the Institute of Astronomy, Cambridge, University of Oxford, and the Max Planck Institute for Astrophysics. Results impacted measurements of the Large-Scale Structure of the Universe, galaxy clustering statistics used by researchers at the Harvard-Smithsonian Center for Astrophysics, and studies of dark matter and cosmological parameters pursued at institutions such as the California Institute of Technology and the Princeton University. The instrument also supported targeted programmes in stellar astrophysics and Galactic structure conducted by groups at the Australian National University and the University of Sydney.
Development was coordinated in the 1990s under the auspices of the Anglo-Australian Observatory with engineering contributions from the Royal Greenwich Observatory, the University of Oxford instrumentation group, and external contractors including firms associated with the UK Science and Technology Facilities Council. Commissioning in 1997 led to operational surveys through the 2000s, with software and hardware upgrades implemented by personnel from the Anglo-Australian Observatory and collaborators at the University of Cambridge and the Australian National University. Later efforts incorporated improved control electronics and enhanced calibration pipelines reflecting algorithmic advances from the European Southern Observatory and data-processing methodologies from the Sloan Digital Sky Survey teams.
Category:Astronomical instruments