The VIALACTEA project has a work package dedicated to “Tools and Infrastructure" and, inside it, a task for the “Database and Virtual Observatory Infrastructure". This task aims at providing an infrastructure to store all the resources needed by the, more purposely, scientific work packages of the project itself. This infrastructure includes a combination of: storage facilities, relational databases and web services on top of them, and has taken, as a whole, the name of VIALACTEA Knowledge Base (VLKB). This contribution illustrates the current status of this VLKB. It details the set of data resources put together; describes the database that allows data discovery through VO inspired metadata maintenance; illustrates the discovery, cutout and access services built on top of the former two for the users to exploit the data content.
The emerging field of AstroInformatics, while on the one hand appears crucial to face the technological challenges, on
the other is opening new exciting perspectives for new astronomical discoveries through the implementation of advanced data mining procedures. The complexity of astronomical data and the variety of scientific problems, however, call for innovative algorithms and methods as well as for an extreme usage of ICT technologies. The DAME (DAta Mining and Exploration) Program exposes a series of web-based services to perform scientific investigation on astronomical massive data sets. The engineering design and requirements, driving its development since the beginning of the project, are projected towards a new paradigm of Web based resources, which reflect the final goal to become a prototype of an efficient data mining framework in the data-centric era.
The 2.6m VST telescope is in installation phase in the ESO observatory of Cerro Paranal. After preliminary tests in
Europe performed jointly by INAF and ESO the tracking system was considered at the readiness level to be shipped to
Chile. The motion control system has already been reintegrated in Chile and is operational again. The final tuning is
going to be performed after the integration of all the telescope subsystems, still in progress. Therefore here the focus is
especially on tests performed in Italy. This paper describes the solutions adopted for the telescope main axes control as
well as the preliminary tracking results. Available test data are related to encoder feedback. Tests have been performed
tracking coordinates of virtual objects. A comprehensive test case to evaluate the performance of different controllers
was needed to proceed in a systematic way. A tracking map derived from the VLT commissioning experience has been
used, spanning all the different conditions for axes positions and speeds, including meridian crossing and tracking near
the blind spot.
The VST active optics software must basically provide the analysis of the image coming from the wavefront sensor (a 10×10 subpupils Shack Hartmann device) and the calculation of primary mirror forces and secondary mirror displacements to correct the intrinsic aberrations of the optical system and the ones originated for thermal or gravity reasons. The software architecture, the simulation code to validate the results and the status of work are here described.
The adapter of the VST telescope hosts many devices handled by the overall telescope control software: a probe system to select the guide star realized with motions in polar coordinates, a pickup mirror to fold the light to the image analysis and guiding cameras, a selectable reference light system and a focusing device. The algorithm to select the guide star depends on the specific geometry of the system. All these devices deeply interface with autoguiding, active optics and field rotation compensation systems. A reverse engineering approach mixed to the integration of new specific solutions has been fundamental to match the ESO commitments in terms of software re-use, in order to smoothen the integration of a new telescope designed and built by an external institute in the ESO environment. The control software architecture is here described, as well as the status of work.
One of the tightest requirements to be respected for a telescope as the VST, hosted in a one of the best astronomical sites as the ESO Paranal Observatory, is an excellent axes control, to obtain the best overall performance of the telescope that, otherwise, can be dramatically affected. The software strategy to control the VST axes (azimuth, altitude, rotator) is here described.
The effects of atmospheric differential refraction on astrophysical measurements are well known. In particular, as a ray of light passes through the atmosphere, its direction is altered by the effects of atmospheric refraction. The amount of this effect depends basically on the variation of the refractive index along the path of the ray. The real accuracy needed in the atmosphere model and in the calculation of the correction to be applied is of course, considerably worse, especially at large zenith angles. On the VLT Survey Telescope (VST) the use of an Atmospheric Dispersion Corrector (ADC) is foreseen at a wide zenith distance range. This paper describes the software design and implementation aspects regarding the analytical correction law discovered to correct the refraction effect during observations with VST.
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 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.
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 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 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 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.
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.
Object recognition is usually obtained by using some kind of different approach based on profile reconstruction, whose results are not always reliable or sufficient for a right object identification. The present paper describes an alternative method to profile calculation, based on color and surface information associated to the images. The method is also used to define the system typology on the basis of a detailed analysis of human instinctive behaviors associated to the task to be performed by the system.