ARGOS at the LBT. Binocular laser guided ground layer adaptive optics
  Having completed its commissioning phase, the Advanced Rayleigh guided
Ground-layer adaptive Optics System (ARGOS) facility is coming online for
scientific observations at the Large Binocular Telescope (LBT). With six
Rayleigh laser guide stars in two constellations and the corresponding
wavefront sensing, ARGOS corrects the ground-layer distortions for both LBT
8.4m eyes with their adaptive secondary mirrors. Under regular observing
conditions, this set-up delivers a point spread function (PSF) size reduction
by a factor of ~2--3 compared to a seeing-limited operation. With the two LUCI
infrared imaging and multi-object spectroscopy instruments receiving the
corrected images, observations in the near-infrared can be performed at high
spatial and spectral resolution. We discuss the final ARGOS technical set-up
and the adaptive optics performance. We show that imaging cases with
ground-layer adaptive optics (GLAO) are enhancing several scientific
programmes, from cluster colour magnitude diagrams and Milky Way embedded star
formation, to nuclei of nearby galaxies or extragalactic lensing fields. In the
unique combination of ARGOS with the multi-object near-infrared spectroscopy
available in LUCI over a 4x4 arcmin field of view, the first scientific
observations have been performed on local and high-z objects. Those high
spatial and spectral resolution observations demonstrate the capabilities now
at hand with ARGOS at the LBT.
