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NAOS, the first AO system of the VLT: on-sky performance
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2003
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EngineeringSpace OpticPrecision NavigationActive OpticsAstronomical Image AnalysisInfrared OpticOptical SystemsClosed Loop OperationRadiation ImagingFlight ValidationPhotometryAircraft NavigationSpace-air-ground Integrated NetworkAvionics SystemActuator Deformable MirrorFirst Ao SystemRadio TelescopeSynchrotron RadiationAstrophysicsAdaptive OpticStar Magnitude
NAOS is the first adaptive optics system installed on the VLT 8‑m telescopes. The system was designed to deliver compensated images to the high‑resolution IR spectro‑imaging camera CONICA, and this paper reports its on‑sky performance. NAOS comprises a 185‑actuator deformable mirror, a tip‑tilt mirror, and visible and near‑IR wavefront sensors, and was built by a French consortium under an ESO contract. During first‑light tests, NAOS achieved a 50 % Strehl ratio under average seeing, reached the diffraction limit at 2.2 μm, remained robust in poor seeing, and delivered substantial correction down to V = 17.6 and K = 13.1 guide stars, with acceptance tests completed by May 2002 and the system slated for community use in October.
NAOS is the first adaptive optics system installed at the VLT 8m telescopes. It was designed, manufactured and tested by a french Consortium under an ESO contract, to provide compensated images to the high angular resolution IR spectro-imaging camera (CONICA) in the 1 to 5 μ<i>m</i> spectral range. It is equipped with a 185 actuator deformable mirror, a tip/tilt mirror and two wavefront sensors, one in the visible and one in the near IR spectral range. It has been installed in November at the Nasmyth focus B of the VLT UT4. During the first light run in December 2001, NAOS has delivered a Strehl ratio of 50 under average seeing conditions for bright guide stars. The diffraction limit of the telescope has been achieved at 2.2 μ<i>m</i>. The closed loop operation has been very robust under bad seeing conditions. It was also possible to obtain a substantial correction with <i>m</i>V=17.6 and <i>m</i>K=13.1 reference stars. The on-sky acceptance tests of NAOS-CONICA were completed in May 2002 and the instrument will be made available to the European astronomical community in October by ESO. This paper describes the system and present the on-sky performance in terms of Strehl ratio, seeing conditions and guide star magnitude.