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In 2007, a companion with planetary mass was found around the pulsating subdwarf B star V391 Pegasi with the timing method, indicating that a previously undiscovered population of substellar companions to apparently single subdwarf B stars might exist. Following this serendipitous discovery, the EXOTIME (http://www.na.astro.it/~silvotti/exotime/) monitoring program has been set up to follow the pulsations of a number of selected rapidly pulsating subdwarf B stars on time-scales of several years with two immediate observational goals: 1) determine Pdot of the pulsational periods P 2) search for signatures of substellar companions in O-C residuals due to periodic light travel time variations, which would be tracking the central star's companion-induced wobble around the center of mass. These sets of data should therefore at the same time: on the one hand be useful to provide extra constraints for classical asteroseismological exercises from the Pdot (comparison with "local" evolutionary models), and on the other hand allow to investigate the preceding evolution of a target in terms of possible "binary" evolution by extending the otherwise unsuccessful search for companions to potentially very low masses. While timing pulsations may be an observationally expensive method to search for companions, it samples a different range of orbital parameters, inaccessible through orbital photometric effects or the radial velocity method: the latter favours massive close-in companions, whereas the timing method becomes increasingly more sensitive towards wider separations. In this paper we report on the status of the on-going observations and coherence analysis for two of the currently five targets, revealing very well-behaved pulsational characteristics in HS 0444+0458, while showing HS 0702+6043 to be more complex than previously thought., Comment: Contribution to: The Fourth Meeting on Hot Subdwarf Stars and Related Objects, 20 - 24 July 2009, Shanghai, China, published 03/2010 by Ap&SS (Open access publication). 12 pages, 14 figures, 5 tables

The VST (VLT Survey Telescope) is a 2.6 m class Alt-Az telescope to be installed at Mount Paranal in Chile, in the European Southern Observatory (ESO) site. The VST is a wide-field imaging facility planned to supply databases for the ESO Very Large Telescope (VLT) science and carry out stand-alone observations in the UV to I spectral range. So far no telescope has been dedicated entirely to surveys; the VST will be the first survey telescope to start the operation, as a powerful survey facility for the VLT observatory. This paper will focus on the axes motion control system. The dynamic model of the telescope will be analyzed, as well as the effect of the wind disturbance on the telescope performance. The main problems and requirements for a telescope position control will also be discussed.

The Galileo Telescope (TNG) seeing monitor is fully automatic and installed 100 m from the TNG. The details and characteristics of the system and a preliminary set of data are given here.

COCHISE (Cosmological Observations at Concordia with High-sensitivity Instrument for Source Extraction) is a 2.6 m telescope located on the high Antarctic Plateau near the Italian-French Concordia Base. The telescope is mainly devoted to Cosmological observations, able to operate between 200 mu m and 3 mm of wavelength. In this paper we describe the main characteristics of the instrument. We also report on the first light, obtained during summer 2010-2011: this result marks the beginning of millimetre astrophysical observations at Concordia. Responsivity, noise equivalent temperature and field of view of the instrument are reported. At present COCHISE is the largest telescope located at Concordia. Beside the scientific expectations, the use of this kind of instrument in the Antarctic environment poses technological aspects of relevant interest: thus COCHISE can be considered as a pathfinder for future Antarctic telescopes.

The Galileo National Telescope (TNG) is an Italian 3.5m telescope to be located on La Palma (Spain). Construction of TNG is well in progress, and the first light should be obtained in the second half of 1995. The TNG main elements have been derived from those of the ESO NTT, although some alternative solutions regarding the components and the management, have been taken into consideration in order to make the system more reliable. Interesting solutions regarding motors, bearings, encoders and the control system adopted to drive the TNG ensure a high performances degree in pointing and tracking and a very low manteinance level.

The Hydrostatic Bearing System (HBS) control hardware of the VST (VLT Survey Telescope), a 2.6 m. class Alt-Az telescope in installation phase at Cerro Paranal in Northern Chile, at the European Southern Observatory (ESO) site, is aimed at controlling all the devices present in the HBS pumping station and at monitoring the pressure values in the different points of the plant. The HBS control system is based mainly on a Local Control Unit (LCU) mounted in the HBS control cabinet and connected to the plant by means of proper I/Fs. A distributed pressure and temperature acquisition system, based on General Purpose (GP) acquisition boards, is also present. A local interlock chain and related enabling signal for the Azimuth Axis interlock chain have been implemented to avoid fault propagation in case of lack of delivery pressure. In the present paper all technical details concerning the control and monitoring of the HBS subsystem are given.

In a modern telescope the Azimuth (AZ) and Altitude (ALT) Axes have to perform a very accurate pointing and tracking. The tracking of celestial objects is a critical operation, during which the telescope axes have to compensate the earth rotation, allowing a stable image integration on the scientific instrument CCD. To accomplish this goal, the two axes control system is provided with state of the art encoders and tachometers, for position and speed feedback, together with motors controlled in torque preload, to avoid backlash effect. The closed loop control system is based on an axes Local Control Unit (LCU), based on VME Computer. In this paper the AZ and ALT Axes Control System of the VST (VLT Survey Telescope) is described. The VST is a 2.6 m class Alt-Azimuthal Survey Telescope in installation phase at Cerro Paranal in Northern Chile, at the European Southern Observatory (ESO) observation site. The VST Telescope was designed and implemented by I.N.A.F., Osservatorio Astronomico di Capodimonte. Nowadays the AZ and ALT axes mechanics and the related control system have already been accepted by ESO, shipped to Chile and integrated in Paranal.

The VST (VLT Survey Telescope) is a 2.6m optical ground-based telescope to be installed in the Cerro Paranal (Chile) observational station of the European Southern Observatory (ESO). It is a joint project of INAF-Osservatorio Astronomico di Capodimonte, responsible of the telescope design and realization, and ESO, responsible for the civil infrastructures and the daily operation of the instrument. The control system of the telescope is by definition an opto-mechatronic system. It combines mechatronic and optical disciplines together with the final aim to produce sharp images of star objects. Feedback control systems are partially based on mechatronic conventional sensors like position transducers, but also optical feedbacks coming from two separate technical CCD sensors are used to implement outer control loops for the compensation of optical aberrations e.g. introduced by the gravity, by shape imperfections or flexures in the mirrors, by thermal effects, by a not perfect alignment of the telescope axes.

This paper shows criteria and strategy followed for the optics design of VST telescope, and foreseen image quality. The optics design has been optimized in order to achieve the high required image quality on the base of main scientific requirements, mechanics constraints coming from the wide CCD mosaic camera and dimensional requirements. Manufacturing reliability integrated operational efficiency, and costs optimization criteria have been also taken into account. The VST optics has been designed in order to have a 2.61 m Alt.az telescope operating from U to I bands with an excellent image quality (80% of Encircled Energy enclosed in less than two pixels) on a wide field of view (1° x 1°). The telescope will have a very high resolution (0.21"/pixel) with a pixel size of 15 μm;. The peculiarity of VST optics design is that telescope configuration is not a pure Ritchey - Chretien, but it is integrated with two different refracting correctors in order to minimize residual field aberrations. One corrector is optimized for observations at small zenith angles (U-I bands), while the other one includes an ADC providing high quality images until zenith angles of 50° (B-I bands). This corrector is a very useful and innovative integrated facility. The optics is being manufactured from Zeiss/LZOS. The telescope is going to be mounted in Napoli before shipment to Chile where it will be installed near the giants VLT units and will be a dedicated wide field imaging facility operating in narrow and wide visible bands

The VLT Survey Telescope (VST) is a 2.6m aperture, wide field, UV to I facility, to be installed at the European Southern Observatory (ESO) on the Cerro Paranal Chile. VST was primarily intended to complement the observing capabilities of VLT with wide-angle imaging for detecting and pre-characterising sources for further observations with the VLT., 2 pages, 2 figures, conference

This paper concerns optomechanics tolerances specifications for VST telescope. It shows the strategy of tolerances definition for optomechanical systems. These prescriptions are the baseline for development and tests of VST telescope optomechanic components. The telescope is provided with an active optics control system, so some tolerances may be relaxed, respect to passive systems designs since they can be actively compensated. Gravitational and thermal deformations have been also considered. The design error budget strategy is described. Manufacturing, mounting and alignment tolerances have been evaluated within the whole telescope image quality error budget, in terms of rms spot radius. Since the telescope is seeing limited, effects of atmospheric seeing have also been considered in the error budget in terms of CIR. Do to its large field of view (1 degree square), the VST optical design (optomechanics tolerances included) is the first source of error if compared to a classical telescope design that has a small field of view. The overall optical quality depends also on telescope configuration (ADC and one-lens corrector or two-lens corrector configuration) and on observational zenith angle (0÷50°).

This paper is about VST active optics system design, specifications and status. The VST is a modified Ritchey-Chretien wide field Alt-Az telescope with a corrector camera (1 square degree field of view), so when all optical components are correctly aligned, only residual aberrations in whole field are present. The major amounts of these aberrations can be introduced by gravitational and thermo opto-mechanical deformations and mirror misalignments. For these reasons active control of the primary mirror shape and secondary mirror position are required to lessen optical aberrations. The aim of active optics is to correct all optical telescope errors in order to make them small compared with external seeing. The VST is essentially compensated for static or slow frequency deformations and misalignments with a band pass from dc to 1/30 Hz, since the corresponding integration time is sufficient to integrate out the external seeing, giving a round image corresponding to the integrated external seeing quality. VST decentering, coma and defocus are corrected by mean of a secondary mirror position control system (a two-stage hexapode system) and spherical, astigmatism, quad-astigmatism and tri-coma are corrected by mean of M1 mirror shape deformation (axial and radial support system). For optical aberrations and guiding measurement an optical sensing arm has been designed.

The Visible Multi-Object Spectrograph VIMOS is a wide field survey instrument in the process of being commissioned for operations at the ESO-VLT. During the first commissioning period, the instrument has confirmed its excellent performances in its three basic modes of operation: direct imaging, multi-slit spectroscopy, and integral field spectroscopy. VIMOS provides the largest imaging field at the VLT with 224 arcmin2. It offers an unprecedented multiplex gain in multi-slit spectroscopy, with on order 800 slits which can be observed simultaneously. The integral field unit has a field up to 54x54 arcsec2, with 6400 spectra recorded at once. The overall efficiency of VIMOS combined to the Melipal unit #3 is confirmed to be as computed on the basis of the measured transmission of optical elements. Image quality is confirmed to be excellent, providing images limited by natural seeing in most conditions. High quality slit masks cut by the laser machine coupled to excellent geometric mask to CCD mapping lead to multi-slit spectra of excellent quality. VIMOS is expected to be offered to the ESO community for reguglar observations in early 2003.

We describe the current status and technical aspects of the GOHSS (Galileo OH Subtracted Spectrograph) project. Here we point out the most critical items and how we have implemented innovative technical solutions to fulfill the compelling requirements imposed by both the optical tolerances and the demands of a high sensitivity. In particular we examine the camera lens mechanics realized in ultra low expansion quartz; the refrigerator system; the IR array mount realized in an unconventional way; the effort put in procuring optical devices with quite large efficiencies. We are also developing the data reduction package along with the instrument simulator: the optimized procedures and the results on the visibility function of galaxies are given as well. Currently the instrument is in the integration phase at the laboratories of the Astronomical Observatory of Rome and the commissioning phase at the telescope is expected to start at the beginning of year 2003.

The VLT Survey Telescope (VST) is a cooperative program between the European Southern Observatory (ESO) and the INAF Capodimonte Astronomical Observatory (OAC), Naples, for the study, design, and realization of a 2.6-m wide-field optical imaging telescope to be operated at the Paranal Observatory, Chile. The VST has been specifically designed to carry out stand-alone observations in the UV to I spectral range and to supply target databases for the ESO Very Large Telescope (VLT). The telescope design, manufacturing and integration are responsibility of OAC. The telescope is in Cassegrain configuration and for this reason the primary mirror cell represents one of the most complex telescope subsystems, designed to host a large amount of auxiliary sub-systems and to support a wide field camera. The paper describes the solutions adopted as a result of an integrated optimized optical and mechanical design.

The VLT Survey Telescope (VST) is a co-operative program between the European Southern Observatory (ESO) and the INAF Capodimonte Astronomical Observatory (OAC), Naples, for the study, design, and realization of a 2.6-m wide-field optical imaging telescope to be operated at the Paranal Observatory, Chile. The telescope design, manufacturing and integration are responsibility of OAC. The VST has been specifically designed to carry out stand-alone observations in the UV to I spectral range and to supply target databases for the ESO Very Large Telescope (VLT). The control hardware is based on a large utilization of distributed embedded specialized controllers specifically designed, prototyped and manufactured by the Technology Working Group for VST project. The use of a field bus improves the whole system reliability in terms of high level flexibility, control speed and allow to reduce drastically the plant distribution in the instrument. The paper describes the philosophy and the architecture of the VST control HW with particular reference to the advantages of this distributed solution for the VST project.

The Virmos-VLT deep survey (VVDS) is aimed to study the evolution of galaxies, large scale structure and AGNs over more than 90% of the current age of the Universe, based on a large number (more than 100.000) of spectra of galaxies. In a first step, the Vimos Spectrograph will be used to measure all galaxies from magnitude limited samples. In a second step, near IR spectroscopy will be obtained with the Nirmos spectrograph, to measure redshifts in the critical range 1.2 AB = 22.5. At the center of one region a deep survey will be conducted for galaxies brighter than I AB = 24. This deep region has also been imaged at the VLA (1400 MHz) to a flux limit of 0.08 mJy and is being observed in X-Rays with XMM.

The VLT Survey Telescope (VST) is a cooperative program between the European Southern Observatory (ESO) and the INAF Capodimonte Astronomical Observatory (OAC), Naples, for the study, design, and realization of a 2.6-m wide-field optical imaging telescope to be operated at the Paranal Observatory, Chile. The VST has been specifically designed to carry out stand-alone observations in the UV to I spectral range and to supply target databases for the ESO Very Large Telescope (VLT). The telescope design, manufacturing and integration are responsibility of TWG and have been carried out on the base of a model of optimized design not only for mechanics but for all telescope subsystems. The paper is an overview on the telescope mechanical design and optimization.

Modern scientific and technological projects are increasingly in competition over scientific aims, technological innovation, performance, time and cost. They require a dedicated and innovative organization able to satisfy contemporarily various technical and logistic constraints imposed by the final user, and guarantee the satisfaction of technical specifications, identified on the basis of scientific aims. In order to satisfy all the above, the management has to be strategically innovative and intuitive, by removing, first of all, the bottlenecks that are pointed out, usually only at the end of the projects, as the causes of general dissatisfaction. More than 30 years spent working on complex multidisciplinary systems and 20 years of formative experience in managing contemporarily both scientific, technological and industrial projects have given the author the possibility to study, test and validate strategies for parallel project management and integrated design, merged in a sort of unique optimized task, using the newly-coined word "Technomethodology". The paper highlights useful information to be taken into consideration during project organization to minimize the program deviations from the expected goals and describe some of the basic meanings of this new advanced method that is the key for parallel successful management of multiple and interdisciplinary activities.

We describe the telescope concept of the VST-the VLT survey telescope-and the scientific and instrumental background which lead to the kick-off of the project for the realization of a 2.6 m telescope for wide field imaging in the optical and infrared to be placed at Paranal, on the VLT plateau within the year 2001. The project for the camera and the data handling and archiving, plus the analysis pipeline are outlined, with particular emphasis on the possible scientific surveys and stand alone projects. We will briefly review some of the scientific projects for which the VST was conceived, and its impact on the VLT science.

We present the integration and performances of the VLT-VIMOS Integral Field spectroscopy Unit. This unit allows to observe a very large 54x54 arcsec2 field on the side of the VIMOS instrument multi-object field in the range 0.37 - 1μm. This unit contains 6400 sets of micro-lenses - fibers - micro-lenses, producing the equivalent of a 72 arcmin x 0.67 arcsec slit projected on the sky. Two spatial resolutions (0.67 arcsec and 0.33 arcsec) are offered, coupled with the low and high spectral resolution of VIMOS. After reviewing the design philosophy, we are presenting the main steps and challenges encountered during integration. Calibration tests conducted in France and at the Paranal observatory as well as the data reduction software that has been developed for IFU are discussed. The first sky images of this very wide Integral Field Unit have been obtained in the early 2002 commissioning periods at VLT.

Neural network models (NN) have emerged as important components for applications of adaptive control theories. Their basic generalization capability, based on acquired knowledge, together with execution rapidity and correlation ability between input stimula, are basic attributes to consider NN as an extremely powerful tool for on-line control of complex systems. By a control system point of view, not only accuracy and speed, but also, in some cases, a high level of adaptation capability is required in order to match all working phases of the whole system during its lifetime. This is particularly remarkable for a new generation ground-based telescope control system. Infact, strong changes in terms of system speed and instantaneous position error tolerance are necessary, especially in case of trajectory disturb induced by wind shake. The classical control scheme adopted in such a system is based on the proportional integral (PI) filter, already applied and implemented on a large amount of new generation telescopes, considered as a standard in this technological environment. In this paper we introduce the concept of a new approach, the neural variable structure proportional integral, (NVSPI), related to the implementation of a standard multi layer perceptron network in new generation ground-based Alt-Az telescope control systems. Its main purpose is to improve adaptive capability of the Variable structure proportional integral model, an already innovative control scheme recently introduced by authors [Proc SPIE (1997)], based on a modified version of classical PI control model, in terms of flexibility and accuracy of the dynamic response range also in presence of wind noise effects. The realization of a powerful well tested and validated telescope model simulation system allowed the possibility to directly compare performances of the two control schemes on simulated tracking trajectories, revealing extremely encouraging results in terms of NVSPI control robustness and reliability. © 2003 Elsevier Science Ltd. All rights reserved.

The VLT Survey Telescope (VST) is a cooperative program between the European Southern Observatory (ESO) and the INAF Capodimonte Astronomical Observatory (OAC), Naples, for the study, design, and realization of a 2.6-m wide-field optical imaging telescope to be operated at the Paranal Observatory, Chile. The telescope design, manufacturing and integration are provided and under responsibility of the Technology Working Group (TWG) of OAC. The VST has been specifically designed to carry out stand-alone observations in the UV to I spectral range and to supply target databases for the ESO Very Large Telescope (VLT). The VST control software will operate the telescope, all the auxiliary subsystems and will manage the interfaces toward the instrumentation. The paper will describe the architecture of the software system, including the solutions adopted to be compliant with the ESO standard software environment.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper is a status report on the VST (VLT Survey Telescope) project, aimed at creating a new-technology wide-field facility at the European Southern Observatory (ESO) at Paranal, Chile. The VST telescope is a 2.6 m alt-az reflector built by INAF - Capodimonte Astronomical Observatory (OAC). The camera is a 16k × 16k CCD mosaic provided by the international OmegaCAM consortium. In spite of a recent disastrous event, which caused the loss of the primary mirror while it was transferred from Europe to Chile by ESO, the goal is still that the facility may start to operate in the first quarter of 2004, as planned.

The VIRMOS Consortium has the task to design and manufacture two spectrographs for ESO VLT, VIMOS (Visible Multi-Object Spectrograph) and NIRMOS (Near Infrared Multi-Object Spectrograph). This paper describes how the Mask Manufacturing Unit (MMU), which cuts the slit masks to be used with both instruments, meets the scientific requirements and manages the storage and the insertion of the masks into the instrument. The components and the software of the two main parts of the MMU, the Mask Manufacturing Machine and the Mask Handling System, are illustrated together with the mask material and with the slit properties. Slit positioning is accurate within 15 micron, equivalent to 0.03 arcsec on the sky, while the slit edge roughness has an rms on the order of 0.03 pixels on scales of a slit 5 arcsec long and of 0.01 pixels on the pixel scale (0.205 arcsec). The MMU has been successfully installed during July/August 2000 at the Paranal Observatory and is now operational for spectroscopic mask cutting, compliant with the requested specifications., Comment: Accepted for publication in PASP April 2001 PASP Latex preprint style, 31 pages including 9 figures (5 jpg2eps compressed)

The VIRMOS consortium of French and Italian institutes is building the Visible Multi-Object Spectrograph (VIMOS) and the NIRMOS for the European Southern Observatory Very Large Telescope. Inside the VIRMOS consortium the Technology Working Group of the Osservatorio Astronomico di Capodimonte is in charge of the design, realization and integration of mechanics, opto-mechanical interfaces, control electronics and low level control software. This paper is an overview on the VIMOS technical project managed by the TWG.

The VIRMOS consortium of French and Italian Institutes is manufacturing 2 wide field imaging multi-object spectrographs for the European Southern Observatory Very Large Telescope, with emphasis on the ability to carry over spectroscopic surveys of large numbers of sources. The Visible Multi-Object Spectrograph, VIMOS, is covering the 0.37 to 1 micron wavelength domain, with a full field of view of 4 by 7 by 8 arcmin 2 in imaging and MOS mode. The Near IR Multi-Object Spectrograph, NIRMOS, is covering the 0.9 to 1.8 microns wavelength range, with afield of view 4 by 6 by 8 arcmin 2 in MOS mode. The spectral resolution for both instrument scan reach up to R equals 5000 for a 0.5 arcsec wide slit. Multi-slit masks are produced by a dedicated Mask Manufacturing Machine cutting through thin Invar sheets and capable of producing 4 slit masks approximately 300 by 300 mm each with approximately slits 5.7 mm long in less than one hour. Integral field spectroscopy is made possible in VIMOS by switching in the beam specially build masks fed by 6400 fibers coming form a 54 by 54 arcsec 2 integral field head with a 80 by 80 array of silica micro-lenses. NIRMOS has a similar IFS unit with a field of 30 by 30 arcmin 2 . These instruments are designed to offer very large multiplexing capabilities. In MOS mode, about 1000 objects can be observed simultaneously with VIMOS, with a S/N equals 10 obtained on galaxies with I equals 24 in one hour, and approximately 200 objects can be observed simultaneously with NIRMOS, with a S/N equals 10 obtained don galaxies with J equals 22, H equals 20.6 in 1h at R eq equals 200. We present here the status of VIMOS, currently under final integration, with expected first light in the summer 2000, together with the final design of NIRMOS presented at the Final Design Review. The VLT-VIRMOS deep redshift survey of more with the final design of NIRMOS presented at the Final Design Review. The VLT-VIRMOS deep redshift survey of more than 150000 galaxies over the redshift range 0 < z < 5 will be undertaken based on 120 guaranteed nights awarded to the project.

The VST (Very Large Telescope Survey Telescope) is an 2.6 m class Alt-Az telescope which will be installed in the European Southern Observatory (ESO) Paranal site, Chile. It has been designed by the Technology Working Group of the Astronomical Observatory of Capodimonte, Italy. The VST is an 1 degree(s) X 1 degree(s) wide-field imaging facility planned to supply databases for the ESO VLT science and carry out stand-alone observations in the UV to I spectral range starting in the year 2001. All the solutions adopted in the VST design comply to the ESO VLT standards. This paper reports a technical overview of the telescope design.

The 3.6 m TNG (Telescopio Nazionale Galileo) Italian alt-ax telescope is now regularly working in La Palma, Canary Islands. The drive and control system of the main axes is working since October, 1997. It has been used for some months to support the installation of optics and other mechanical subsystems. Since June, 1998 the control system is integrated in the overall TNG informatic environment. In 1998 TNG has seen its first light. This paper reports the last most significant results for axes control, compared with the TNG tracking error requirements.

The TNG is an Italian 3.6 m Alt-Az telescope installed in La Palma, Canary Island. The drive and control system of the main axes is working since October, 1997. It has been used for some months to support the installation of optics and other mechanical subsystems. Since June, 1998 the control system is integrate in the overall TNG informatic environment. In 1998 TNG has seen its first light. After the installation of the rotator drive system and of the Nasmyth 'A' focus instrumentation, the TNG telescope project is in advanced optimization phase. This paper reports the recent updates in TNG axes motion control and the last most significant results.

The TNG is an Italian 3.6 m Alt-Az telescope installed at La Palma international astronomical Observatory Roque de Los Muchachos. It is equipped with two Nasmyth foci where the instrumentation is permanently installed. The first one is devoted to imaging and to support adaptive optics equipment and the other is devoted to spectroscopy. At each of the two foci the rotation of the field implied by the Alt-Az mount of the telescope needs to be compensated by the movement of one of the two rotator axes. The drive and control system and the solutions adopted for the motion control are here briefly described.

Some considerations about vibrations affecting optical telescopes tracking performance are here reported. They are based on experiences done in some very different case studies. Generally speaking the term noise comprises vibrations induced by the telescope to the pillar and vice versa. In some cases undesired mechanical connections between the telescope and the enclosure can produce the same effects namely a deprezation of the telescope tracking performance. Due to the always-different telescope/enclosure design the solution adopted to resolve vibration problems can also be substantially different.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The commissioning phase of the Telescopio Nazionale Galileo is started during the first half of 97. Large parts of the drive, the optical and the control system have been mounted at the telescope in site (LaPalma, Canary Islands). The telescope is expected to be ready for the technical first- light during February - March 98 while the instrumentation first-light is expected for mid 98. On this review of the commissioning operations we will describe the problems encountered and the results achieved integrating the main telescope subsystems.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We present the current design of the VIsible Multi-Object Spectrograph (VIMOS) and the Near InfraRed Multi-Object Spectrograph (NIRMOS) for the European Southern Observatory Very Large Telescope. The basic scientific requirement is to conduct very deep redshift surveys of large quantities of objects, in a minimum number of nights. The technical specifications are to allow for a large multiplex gain over a wide field, and a high efficiency of the optical train, over the 0.37 to 1.8 micrometer domain. The baseline technical concept is built around 4 channels, covering 4 X 7 X 8 arcmin2 for VIMOS and 4 X 7 X 7 arcmin2 for NIRMOS. Each channel is an imaging spectrograph with a large field adaptation lens, a collimator, grisms or filters, and a F/1.8 camera, coupled to a 2048 X 4096 pixels CCD for VIMOS, and a 20482 HgCdTe Rockwell array for NIRMOS. The unique multiplex gain allows to obtain spectra of up to 840 object simultaneously with VIMOS, and up to 170 with NIRMOS (10 arcsec slits). An integral field spectroscopy mode with more than 6400 fibers coupled to micro-lenses will be available for VIMOS, covering a 1 X 1 arcmin2 field. The VLT-VIRMOS survey of more than 150,000 galaxies is planned down to magnitudes IAB equals 24, coupled to an ultra deep probe to IAB equals 26.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The encoder is the most used angular transducer in position control applications, such as the main axes position control of a telescope. In astronomical applications a very high precision in axes control is required. So a good encoder system design is essential to satisfy the requirements settled by the scientific goals. Today very good encode system are provided by several suppliers, with multiple readouts and error compensation capabilities into increase the reading precision and lessen the errors. Nevertheless during the lifetime of the system some unexpected errors can arise. In this paper some techniques to recognize, analyze and lessen the unavoidable encoder system error are described, with reference to some case studied.

The TT1 is a 1.54 m Alt-Az telescope designed and built by the Technology Working Group of the Astronomical Observatory of Capodimonte, Naples, Italy. The standardization process is of course one of the fundamental requirements for telescope control system design and development, well considered in the TT1 design. In this paper we present the approach used to identify a control system applicable to medium-size Alt-Az telescope. The TT1 control system architecture is based on a distributed working flow and it is PC-based, i.e. organized in several interconnected standard PCs and standard fast communication protocol. Every PC is based on the 'dedicated processing unit' concept and it makes real time own tasks independently by other units. Also, the extremely reduced communication flow between PCs, and the internal organization based on the preference given to software rather than hardware solutions, makes its control system extremely reliable, easily reconfigurable and upgradable, obsolescence deprived and independent from any hardware choice.

The Galileo National Telescope is a 3.6 meter Alt-Az telescope installed at the Astronomical Observatory of the Roque de Los Muchachos in La Palma, Canary Islands. The Galileo drive and control systems were designed and developed by the Technology Working Group of the Capodimonte Astronomical Observatory, Naples. Apart from a short review of the drive system, the paper describes a novelty in the adaptive preload sub-system.

The performance of on Alt-Az telescope depend strongly on its operating conditions. During tracking Alt-Az telescopes generally move slow but in some cases the dynamic range is large. Anyway the position errors must always be as close as possible to zero. A fixed structure controller cannot optimize the telescope performance in terms of error amount in the whole requested dynamic range. On the contrary a digital controller has the ability to modify its structure and its parameter values during operations, according to the instantaneous error values, system status, system actual sped and system characterization. This paper analyzes the problem of stability using such a variable structure controller in a case study.

The Galileo National Telescope (TNG) is a 3.6 meter Alt-Az telescope installed at the Astronomical Observatory of the Roque de Los Muchachos in La Palma, Canary Islands (Spain). The TNG motion control system, designed and realized by the Technology Working Group (TWG), is completely digital because of the versatility of this system topology. In a digital control system using an encoder as transducer means to have a digital feedback signal, therefore directly comparable with the reference without any conversion that is essential with other kinds of transducers. In the following the Galileo telescope (TNG) encoder system with its control electronics and the management software are described. It has been realized by a collaboration between the Heidenhain Company and the TWG. The TNG encoder system, at the state of the art, has one of the highest performances in the telescopes field, in terms of resolution, accuracy, readout time, reliability.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Galileo National Telescope (TNG) is a 3.6-m Alt-Az telescope installed at the Astronomical Observatory of the Roque de Los Muchachos in La Palma, Canary Islands (Spain). The Galileo drive and control systems were designed and developed by the Technology Working Group (TWG) of the Capodimonte Astronomical Observatory, Naples (Italy). This paper presents a description of the dynamic model identification approach, and its use in the controller design.

Recently, neural network models (NN), such as the multilayer perceptron (MLP), have emerged as important components for applications of adaptive control theories. Their intrinsic generalization capability, based on acquired knowledge, together with execution rapidity and correlation ability between input stimula, are basic attributes to consider MLP as an extremely powerful tool for on-line control of complex systems. By a control system point of view, not only accuracy and speed, but also, in some cases, a high level of adaptation capability is required in order to match all working phases of the whole system during its lifetime. This is particularly remarkable for a telescope control system. In fact, strong changes in terms of system speed and instantaneous position error tolerance are necessary. In this paper we introduce the idea of a new approach (NVSPI, neural variable structure PI) related to the implementation of a MLP network in an Alt-Az telescope control system to improve the PI adaptive capability in terms of flexibility and accuracy of the dynamic response range.

The performance of on Alt-Az telescope depend strongly on its operating conditions. During pointing the telescope can move at a relatively high velocity, and the system can tolerate trajectory position errors higher than during tracking. On the contrary, during tracking Alt-Az telescopes generally move slower but still in a large dynamic range. In this case the position errors must be as close to zero as possible. Furthermore the two pointing and tracking phases are executed in sequence without a well defined switch phase between them. A fixed structure controller cannot optimize the telescope performance in terms of error amount in the whole requested dynamic range. On the contrary a digital controller has the ability to modify its structure and its parameter values during operations, according to the instantaneous error values, system status, system actual speed and system characterization. This paper analyzes the problem of tracking errors and the solutions adopted in a case study.

The Galileo National Telescope is a 3.6 meter Alt-Az telescope installed at the Astronomical Observatory of the Roque de Los Muchachos in La Palma, Canary Islands. The Galileo drive and control systems were designed and developed by the Technology Working Group of the Capodimonte Astronomical Observatory, Naples. This paper reports a description of the systems. The telescope test results in the Ansaldo Company workshop, the present situation and the foreseen improvements of the control system are also described.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.