AAOmega spectrograph

AAOmega spectrograph
Diceman Stephen West · CC BY-SA 3.0 · source
Name	AAOmega
Caption	AAOmega at the Anglo-Australian Telescope
Type	Spectrograph
Institution	Anglo-Australian Observatory
Telescope	Anglo-Australian Telescope
Wavelength	Optical
Resolution	1,200–10,000
First light	2006

AAOmega spectrograph The AAOmega spectrograph is a fiber-fed optical spectrograph mounted at the Anglo-Australian Telescope designed for wide-field multi-object spectroscopy. It was developed and commissioned by teams associated with the Anglo-Australian Observatory, Australian Astronomical Observatory, and collaborating institutions to replace the Two Degree Field facility, enabling large-scale surveys of stars and galaxies with simultaneous observations across a two-degree field. AAOmega provided critical datasets for projects associated with organizations such as the European Southern Observatory, National Aeronautics and Space Administration, NASA, and national research councils.

Introduction

AAOmega was conceived to advance programs led by groups at the Research School of Astronomy and Astrophysics, University of Sydney, and University of Oxford and to support surveys akin to those conducted by the Sloan Digital Sky Survey and the Two Micron All Sky Survey. The instrument combined roots in the Two Degree Field fibre positioner with a new bench-mounted dual-beam spectrograph, enabling comparisons with facilities like the Very Large Telescope and the Subaru Telescope while servicing southern-hemisphere initiatives connected to the Anglo-Australian Observatory and the Commonwealth Scientific and Industrial Research Organisation.

Design and Instrumentation

AAOmega's optical bench carried red and blue arms using gratings and dichroic beamsplitters similar in concept to designs deployed at the Keck Observatory and the Gemini Observatory. The spectrograph received light from the Two Degree Field robotically positioned fibers originally developed at the Anglo-Australian Observatory, with fibers routed to fiber pseudoslits and projected onto CCD detectors produced by vendors used by the European Southern Observatory and the Space Telescope Science Institute. The instrument incorporated optical components and mechanics influenced by designs from the Institute of Astronomy, Cambridge, the Harvard & Smithsonian, and the Max Planck Institute for Astronomy for stability and thermal control. The spectrograph's gratings provided variable resolution useful for programs at the Royal Observatory Edinburgh and calibration strategies consistent with wavelength reference standards employed by the National Institute of Standards and Technology.

Operational Modes and Performance

AAOmega operated in multi-object spectroscopy mode across a two-degree field, supporting up to 392 science fibers simultaneously—an approach comparable to multiplexed instruments at the Anglo-Australian Telescope and the William Herschel Telescope. The dual-beam configuration offered resolving powers from ~1,200 for low-resolution redshift work to ~10,000 for kinematic and abundance studies, enabling projects analogous to those performed at the European Southern Observatory's instruments. Operational performance benefited from collaborations with observatory staff at the Siding Spring Observatory and scheduling coordination with surveys influenced by programmes at the Australian National University and the University of Melbourne.

Survey Programs and Scientific Results

AAOmega played a central role in major surveys such as the WiggleZ Dark Energy Survey, the Galaxy And Mass Assembly survey, and follow-up programs for targets from the Two Micron All Sky Survey and the Sloan Digital Sky Survey. The instrument contributed to measurements of baryon acoustic oscillations relevant to analyses by teams at the Perimeter Institute, constraints on large-scale structure studied by researchers at the Max Planck Institute for Astrophysics, and stellar population investigations coordinated with groups at the Institute of Astronomy, Cambridge and Monash University. AAOmega data underpinned discoveries about galaxy evolution, dark energy parameters investigated alongside European Space Agency mission science teams, and stellar kinematics tied to studies at the Leiden Observatory and the Instituto de Astrofísica de Canarias.

Data Reduction and Calibration

Data reduction for AAOmega employed pipelines developed in collaboration with software groups at the Australian Astronomical Observatory, the University of Oxford, and the Anglo-Australian Observatory. Calibration strategies used arc lamps and sky-subtraction techniques benchmarked against procedures from the Sloan Digital Sky Survey and the European Southern Observatory pipelines, while flux calibration referenced spectrophotometric standards known to teams at the Space Telescope Science Institute and the Royal Observatory Edinburgh. Reduction software interfaced with databases managed by institutions like the Centre for Astrophysics and Supercomputing and adhered to provenance practices similar to those at the National Aeronautics and Space Administration archives.

Installation, Commissioning, and Upgrades

AAOmega was installed at the Anglo-Australian Telescope and achieved first light in the mid-2000s after commissioning campaigns involving engineers from the Anglo-Australian Observatory, academics from the University of Sydney, and instrument scientists associated with the University of Oxford. Subsequent upgrades addressed detector performance, fiber refurbishments, and software improvements influenced by efforts at the Gemini Observatory and the Keck Observatory, while maintenance cycles coordinated with staff from the Siding Spring Observatory and the Australian Astronomical Observatory ensured operational continuity.

Collaborations and Observatories Using AAOmega

AAOmega was operated primarily at the Anglo-Australian Telescope with scientific collaborations spanning the Australian National University, the University of Sydney, the University of Oxford, the Max Planck Society, and institutions across Europe, North America, and Asia. The instrument supported international survey consortia that included members from the European Southern Observatory, the Space Telescope Science Institute, Monash University, the Research School of Astronomy and Astrophysics, and the Commonwealth Scientific and Industrial Research Organisation.

Category:Spectrographs Category:Anglo-Australian Telescope instruments