Performance of AAOmega: the AAT multi-purpose fiber-fed spectrograph

Abstract

AAOmega is the new spectrograph for the 2dF fibre-positioning system on the Anglo-Australian Telescope. It is a bench-mounted, double-beamed design, using volume phase holographic (VPH) gratings and articulating cameras. It is fed by 392 fibres from either of the two 2dF field plates, or by the 512 fibre SPIRAL integral field unit (IFU) at Cassegrain focus. Wavelength coverage is 370 to 950nm and spectral resolution 1,000-8,000 in multi-Object mode, or 1,500-10,000 in IFU mode. Multi-object mode was commissioned in January 2006 and the IFU system will be commissioned in June 2006.The spectrograph is located off the telescope in a thermally isolated room and the 2dF fibres have been replaced by new 38m broadband fibres. Despite the increased fibre length, we have achieved a large increase in throughput by use of VPH gratings, more efficient coatings and new detectors -amounting to a factor of at least 2 in the red. The number of spectral resolution elements and the maximum resolution are both more than doubled, and the stability is an order of magnitude better.The spectrograph comprises: an f/3.15 Schmidt collimator, incorporating a dichroic beam-splitter; interchangeable VPH gratings; and articulating red and blue f/1.3 Schmidt cameras. Pupil size is 190mm, determined by the competing demands of cost, obstruction losses, and maximum resolution. A full suite of VPH gratings has been provided to cover resolutions 1,000 to 7,500, and up to 10,000 at particular wavelengths.

The SAMI Galaxy Survey: Early Data Release

“…This has a direct influence on our ability to carry out precise sky subtraction (Sharp, Brough & Cannon 2013). To examine the throughput estimates we measure the rms scatter in throughput over the typical 7 × 1800 s exposures taken for each field.…”

“…SAMI makes use of hexabundles, bundles of 61 fibres that are fused together and have a high optical performance and ∼75 per cent filling factor Bryant et al 2011Bryant et al , 2014a. The fibres feed into the existing AAOmega spectrograph (Sharp et al 2006), a double-beamed spectrograph that offers a range of configurations suitable for galaxy spectroscopy. Since its commissioning in 2012, SAMI observations have been used for studies of galactic winds (Fogarty et al 2012; Ho et al 2014), the kinematic morphology-density relation (Fogarty et al 2014) and star formation in dwarf galaxies (Richards et al 2014).…”

The SAMI Galaxy Survey: Data Release One with emission-line physics value-added products

“…Silk & Mamon 2012), and are clearly detected by combining gaseous emissionline ionisation diagnostics with kinematics (e.g. Sharp & Bland-Hawthorn 2010;Fogarty et al 2012;Ho et al 2014Ho et al , 2016a. Gas inflows can be traced using the measurement of misalignment between gas and stellar kinematics (e.g.…”

“…The 13 IFUs and 26 sky fibres are inserted into pre-drilled plates using magnetic connectors. Optical fibres from SAMI feed into AAOmega, a bench-mounted double-beam optical spectrograph (Sharp et al 2006). AAOmega provides a selection of different spectral resolutions and wavelength ranges.…”

An X-ray and UV flare from the galaxy XMMSL1 J061927.1-655311

“…We observed XMMSL1 J0619-65 with the AAOmega 2dF spectrograph (Saunders et al 2004;Sharp et al 2006) at the prime focus of the Anglo-Australian Telescope on 2012-12-03 for 3 ×600 s, in order to obtain an optical classification of the source and to search for transient emission lines excited by the flare. We used the 580V (3700−5800 A) and 385R (5600−8800 A) low-resolution gratings (R 1300).…”