The Multi-Conjugate Adaptive Optics Demonstrator (MAD) built by ESO with the contribution of two external consortia
is a powerful test bench for proving the feasibility of Multi-Conjugate (MCAO) and Ground Layer Adaptive Optics
(GLAO) techniques both in the laboratory and on the sky. MAD is based on a two deformable mirrors correction system
and on two multi-reference wavefront sensors (Star Oriented and Layer Oriented) capable to observe simultaneously
some pre-selected configurations of Natural Guide Stars. MAD corrects up to 2 arcmin field of view in K band. After a
long laboratory test phase, it has been installed at the VLT and it successfully performed on-sky demonstration runs on
several astronomical targets for evaluating the correction performance under different atmospheric turbulence conditions.
In this paper we present the results obtained on the sky in Star Oriented mode for MCAO and GLAO configurations and
we correlate them with different atmospheric turbulence parameters. Finally we compare some of the on-sky results with
numerical simulations including real turbulence profile measured at the moment of the observations.
The purpose of the recent installation of eight interference filters in UVES is to isolate certain echelle orders to allow the use of a maximal slit length of 30". The typical decker height of the spectrograph slit for science operations is usually of the order of 10-12". The central wavelength of each filter was chosen to permit observations of the most important emission lines in extended objects. We discuss the performance of these filters and show the first science images obtained with the test run.
This work presents the use of system modeling with the aim of maintaining and improving instrument performances. The complexity and cryogenic nature of infrared systems prevent continuous hardware upgrades, so that the advantages of modeling are of high value. Two applications of modeling and basic control theory are shown. The first example concerns the performance monitoring of the ISAAC cryogenic system. The measured and simulated cold structure temperatures are compared in real time, allowing for anticipation of possible failures of the cooling system and therefore for reduction of operational downtime. The second case is about the position control of the duo-echelle grating of the VISIR spectrometer. The controlled system was identified and simulated to select controller parameters that improve the image stability. Preliminary results show the possibility to get better compensation of the disturbances induced by the telescope movements, leading to an enhancement of the data quality.
The European Southern Observatory (ESO) operates its Very Large Telescope (VLT) on Cerro Paranal (Chile) with to date 11 scientific instruments including two interferometric instruments and their numerous auxiliary systems at 4 Unit Telescopes (UTs) and 3 Auxiliary Telescopes (ATs). The rigorous application of preventive and corrective maintenance procedures and a close monitoring of the instruments' engineering data streams are the key ingredient towards the minimization of the technical downtime of the instruments. The extensive use of standardized hardware and software components and their strict configuration control is considered crucial to efficiently manage the large number of systems with the limited human and technical resources available. A close collaboration between the instrument engineers, the instrument scientists in instrument operation teams (IOTs) turns out to be vital to maintain and to the performance of the instrumentation suite. In this paper, the necessary tools, workflows, and organizational structures to achieve these objectives are presented.
This paper presents miscellaneous activities related to instrumentation taking place at Paranal Observatory. The number of instruments and / or facilities that will eventually equip the Observatory (VLT, VLTI, VST, VISTA)is about 20. An adequate organization (human and technical)is required to ensure configuration control and efficient preventive and corrective maintenance (hardware and software). Monitoring instrument performance is a key feature to guarantee success of operations and minimize technical downtime. Some observational projects are carried out with the aim of characterizing the Paranal sky conditions in the visible and the IR, in emission and absorption. Efforts are being developed to monitor, characterize and archive the transparency conditions at night.