Commissioning of the adaptive optics supported LUCI instruments at the Large Binocular Telescope: results

Abstract

The LUCI instruments are a pair of NIR imagers and multi-object spectrographs located at the front bent Gregorian foci of the Large Binocular Telescope (LBT). One of their special features is their diffraction-limited imaging and long-slit spectroscopic capability in combination with the LBT adaptive secondary mirrors. This allows to achieve a spatial resolution down to 60mas and a spectral resolution of up to 25000. Switching from seeing-limited to diffraction-limited observations changes several operational aspects due to features such as the non-common path aberration or the flexure of the instruments. They all require novel techniques to optimize the image quality and to maximize the scientific return. Non-common path aberration can be corrected via look-up tables. For active flexure compensation the night-sky emission is used. The commissioning of the instruments in diffraction-limited mode on sky is largely finished and the instruments have been handed over to the LBT in April 2018.