Overview

UCLES is a cross-dispersed echelle spectrograph located at the coude focus offering high resolution and good wavelength coverage. From its original design UCLES recieves light from the telescope via a 5 mirror coude train, which is the default UCLES light path. UCLES offers a resolution of 40,000-120,000 depending on the slit width and CCD binning. The 79 l/mm grating gives slightly less wavelength coverage than the 31.6 l/mm grating, but offers a longer slit for extended objects, or better sky subtraction on fainter targets. Switching between the two gratings is trivial. The detector, an EEV2 2K x 4K CCD has excellent quantum efficiency over a wide range of optical wavelengths. However, at wavelengths longer than ~7000A there is some fringing of the detector that could cause reduction challenges for programs working at those wavelengths (see the EEV2 Web page for more information). Please note that the MITLL3 detector has been decommissioned as of semester 2, 2016.

CYCLOPS2: UCLES (with the 79 l/mm echelle only) can be used with the CYCLOPS2 cassegrain fibre-feed to observe single objects. It provides 50% improved resolution over a typical 1" wide slit, along with about 50% higher photon collecting power in typical AAT seeing. There is also a fibre for simultaneous wavelength calibration with a Thorium-Uranium-Xenon arc lamp. The UCLES instrument page carries more detailed information on the use of CYCLOPS2.

For questions regading UCLES please contact the Instrument Scientist, Duncan Wright (duncan.wright@aao.gov.au)

 

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