Instrumentation Status for the AAT

Status of Common-User Instruments

AAOmega + 2dF Multi-Object Spectroscopy

During 2014, both the red and blue CCDs of AAOmega were upgraded.  In the blue, this has increased the throughput by an order of ~5%, but more importantly, the blue chip is cosmetically much cleaner with only 0.04% of the pixels flagged as bad (compared to 0.8% for the old blue CCD). In the red, the new CCD provides a significant increase in throughput as well as extend the throughput out to ~10,000A. 

AAOmega is a dual-beam, bench-mounted spectrograph for the 2dF top end. Applicants can expect that configuring a single field of 392 science fibres and 8 guide fibres will take around 45min (including overheads) depending on the complexity of the field configuration and the number of fibre moves required.

An alternate dichroic, procured by the WiggleZ team and the AAO, is available to all AAOmega users. This dichroic shifts the transition wavelength between the blue and red cameras from 5700 Å to 6700 Å, and allows full wavelength coverage with the 385R grating right out to ~10,000 Å.

All 2dF MOS applications must pay particular attention to the quality of their astrometry, and should give details about this in their proposal.

AAOmega users considering the use of Nod & Shuffle techniques should discuss their needs with the observatory prior to submitting their proposal, to ensure that the extra workload for the user, and significant exposure time overheads involved, are commensurate with the improvement in data quality.

Further details about the capabilities of AAOmega are available from this website.

AAOmega + KOALA Integral Field Unit

The AAO has replaced SPIRAL with the new KOALA IFU feed for AAOmega as of Semester 14A, following commissioning in Semester 13B. Information on KOALA performance can be found in the February 2013 AAO newsletter. 

KOALA (Kilo-fibre Optical AAT Lenslet Array) is a 1000 element fibre feed to AAOmega, a dual-beam, bench-mounted spectrograph. KOALA has a selectable field of view of 24"x18" or 43"x32", depending on the desired spatial resolution (0.7" or 1.25"), an increase in throughput over SPIRAL at all wavelengths, particularly at the extreme blue, and simplified field rotation. The 2dfdr software package handles basic reduction of KOALA data, but we are currently developing new Python scripts that combine observations of a single source and deal with the spatial rebinning of the data onto a square spatial grid. 


HERMES is a four-channel, bench-mounted high-resolution spectrograph for use with the 2dF top end. The wavelength ranges of the four channels are fixed at 4715-4900 Å, 5649-5873 Å, 6478-6737 Å and 7585-7887 Å. The spectral resolution is nominally R~28,000, which can be raised to R~45,000 with the use of a slitmask in the spectrograph with ~50% light loss.

All 2dF MOS applications must pay particular attention to the quality of their astrometry, and should give details about this in their proposal. Recent improved mapping of distortions introduced by the gripper gantry have improved the reliability of fibre positioning down to 0.3 arcsec or better. HERMES+2dF field plates have 8 guide fibres and 392 science fibres.


It is expected that Veloce will be commissioned during the course of semester 2019A. Veloce will be a stabilised, high-resolution (R~80000) echelle spectrograph. Initially Veloce will have only one of its three possible 'arms', each covering a different wavelength region, the first arm 'Rosso' will cover ~580 - 930nm. Veloce will be fed by a 26 hexagonal fibre integral field unit (19 target, 2 calibration, 5 sky/background), with an on-sky target area with a diameter of 2.5" and with spatial scrambling through octagonal fibres. The optional simultaneous calibration will be a Menlo Systems laser comb for extremely precise wavelength calibration and/or a Thorium-Uranium-Xenon arc lamp. Veloce will be suitable for observing single targets brighter than i<14 magnitude and will particularly good for red targets such as the cool M dwarf stars.

Prospective Veloce users should read the Veloce overview webpage, and/or contact the instrument scientist, Duncan Wright, for more information. Some additional information is also available here


Visitor Instruments

Proposals for the use of visitor instruments on the AAT are welcome. However. all applicants seeking to use a visitor instrument must first obtain the permission of the SSO Director, even if that instrument has been used previously.

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