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Gaia Data Release 2: The astrometric solution
Context. Gaia Data Release 2 (Gaia DR2) contains results for 1693 million sources in the magnitude range 3 to 21 based on observations collected by the European Space Agency Gaia satellite during theExpand
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Gaia Data Release 1 - Astrometry: one billion positions, two million proper motions and parallaxes
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 monthsExpand
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The Tycho-Gaia astrometric solution. How to get 2.5 million parallaxes with less than one year of Gaia data
Context. The first release of astrometric data from Gaia will contain the mean stellar positions and magnitudes from the first year of observations, and proper motions from the combination of GaiaExpand
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Determination of stellar ages from isochrones: Bayesian estimation versus isochrone fitting
We present a new method, using Bayesian estimation, to determine stellar ages and their uncertainties from observational data and theoretical isochrones. The result for an individual star is obtainedExpand
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Atmospheric Intensity Scintillation of Stars. III. Effects for Different Telescope Apertures
Stellar intensity scintillation in the optical was extensively studied at the astronomical observatory on La Palma (Canary Islands). Atmospheric turbulence causes "flying shadows" on the ground, andExpand
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Astrometric radial velocities. III. Hipparcos measurements of nearby star clusters and associations
Radial motions of stars in nearby moving clusters are determined from accurate proper motions and trigonometric parallaxes, without any use of spectroscopy. Assuming that cluster members share theExpand
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We provide a revised assessment of the number of exoplanets that should be discovered by Gaia astrometry, extending previous studies to a broader range of spectral types, distances, and magnitudes.Expand
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The astrometric core solution for the Gaia mission. Overview of models, algorithms, and software implementation
Astrometric Global Iterative Solution for Gaia, a global solution to determine the astrometric parameters for a subset of primary sources. Expand
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Natural Transfer of Viable Microbes in Space: 1. From Mars to Earth and Earth to Mars
The possibility and probability of natural transfer of viable microbes from Mars to Earth and Earth to Mars traveling in meteoroids during the first 0.5 Ga and the following 4 Ga are investigated,Expand
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Gaia Data Release 1 - Reference frame and optical properties of ICRF sources
Context. As part of the data processing for Gaia Data Release 1 (Gaia DR1) a special astrometric solution was computed, the so-called auxiliary quasar solution. This gives positions for selectedExpand
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