Alberto Vecchiato

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A general relativistic scenario is utilized to build a non-perturbative model, in Schwarzschild metric, for the representation of observed angles among star pairs. This model is then applied to an end-to-end simulation of the GAIA satellite, a concept for global astrometry within the 2000+ scientific program of the European Space Agency. GAIA is expected to(More)
Modern astrometry is based on angular measurements at the micro-arcsecond level. At this accuracy a fully general relativistic treatment of the data reduction is required. This paper concludes a series of articles dedicated to the problem of relativistic light propagation, presenting the final microarcsecond version of a relativistic astrometric model which(More)
Gaia is an ambitious space mission of the European Space Agency which will chart a three-dimensional map the Milky Way to study the composition formation and evolution of our Galaxy. Our research team is developing the AVU-GSR verification module, aiming to obtain a reconstruction of the celestial sphere using a subset of GAIA observations. The authors(More)
A non-perturbative general relativistic approach to global astrometry was developed by de Felice et al. (1998) to handle satellite astrometry data in a genuine relativistic framework. In this contribution, the framework above has been further exploited to account for stellar motions and parallax. Because of the relevance that accurate knowledge (to 10 5 or(More)
The discovery and subsequent detailed study of T dwarfs have provided many surprises and pushed the physics and modelling of cool atmospheres in unpredicted directions. Distance is a critical parameter for studies of these objects to determine intrinsic luminosities, test binarity and measure their motion in the Galaxy. We describe a new observational(More)
Gaia is a 5-year ESA (European Space Agency) cornerstone mission launched at the end of 2013. Its main goal is the production of a 5-parameter astrometric catalogue (i.e. positions, parallaxes and the two components of the proper motions) at the micro-arcsecond level for about 1 billion stars of our Galaxy by means of high-precision measurements. The main(More)
Context. Gaia Data Release 1 (Gaia DR1) contains astrometric results for more than 1 billion stars brighter than magnitude 20.7 based on observations collected by the Gaia satellite during the first 14 months of its operational phase. Aims. We give a brief overview of the astrometric content of the data release and of the model assumptions, data processing,(More)
We present a new catalog of absolute proper motions and updated positions derived from the same Space Telescope Science Institute digitized Schmidt survey plates utilized for the construction of the Guide Star Catalog II. As special attention was devoted to the absolutization process and removal of position, magnitude and color dependent systematic errors(More)