Joint astrometric solution of Hipparcos and Gaia: A recipe for the Hundred Thousand Proper Motions project

Abstract

The first release of astrometric data from Gaia is expected in 2016. It will contain the mean stellar positions and magnitudes from the first year of observations. For more than 100 000 stars in common with the Hipparcos Catalogue it will be possible to compute very accurate proper motions due to the time difference of about 24 years between the two missions. This Hundred Thousand Proper Motions (HTPM) project will be part of the first release. Our aim is to investigate how early Gaia data can be optimally combined with information from the Hipparcos Catalogue in order to provide the most accurate and reliable results for HTPM. The Astrometric Global Iterative Solution (AGIS) was developed to compute the astrometric core solution based on the Gaia observations and will be used for all releases of astrometric data from Gaia. We adapt AGIS to process Hipparcos data in addition to Gaia observations, and use simulations to verify and study the joint solution method. For the HTPM stars we predict proper motion accuracies between 14 and 134 muas/yr, depending on stellar magnitude and amount of Gaia data available. Perspective effects will be important for a significant number of HTPM stars, and in order to treat these effects accurately we introduce a scaled model of kinematics. We define a goodness-of-fit statistic which is sensitive to deviations from uniform space motion, caused for example by binaries with periods of 10-50 years. HTPM will significantly improve the proper motions of the Hipparcos Catalogue well before highly accurate Gaia- only results become available. Also, HTPM will allow us to detect long period binary and exoplanetary candidates which would be impossible to detect from Gaia data alone. The full sensitivity will not be reached with the first Gaia release but with subsequent data releases. Therefore HTPM should be repeated when more Gaia data become available.

arXiv commentRevised manuscript following referee report. Accepted for publication in A&A

References in corpus (5)

• Validation of the new Hipparcos reduction
• Local stellar kinematics from Hipparcos data
• The astrometric core solution for the Gaia mission. Overview of models, algorithms and software implementation
• XHIP: An Extended Hipparcos Compilation
• Radial velocities for the Hipparcos-Gaia Hundred-Thousand-Proper-Motion project

Cited by in corpus (32)

• Gaia Data Release 1: Astrometry - one billion positions, two million proper motions and parallaxes
• Close encounters of the stellar kind
• The Hipparcos-Gaia Catalog of Accelerations
• The GALAH Survey: Observational Overview and Gaia DR1 companion
• PLATO as it is: a legacy mission for Galactic archaeology
• The mass of the young planet Pictoris b through the astrometric motion of its host star
• An Ultra-Hot Neptune in the Neptune desert
• Multiplicity of Galactic Cepheids and RR Lyrae stars from Gaia DR2 - I. Binarity from proper motion anomaly
• The Gaia DR1 Mass-Radius Relation for White Dwarfs
• The detection and characterisation of 54 massive companions with the SOPHIE spectrograph -- 7 new brown dwarfs and constraints on the BD desert
• Microarcsecond Astrometry: Science Highlights from Gaia
• When the tale comes true: multiple populations and wide binaries in the Orion Nebula Cluster
• The Gemini Planet Imager Exoplanet Survey: Dynamical Mass of the Exoplanet beta Pictoris b from Combined Direct Imaging and Astrometry
• Gaia-like astrometry and gravitational waves
• A Gaia study of the Hyades open cluster
• Astrometry and exoplanets in the Gaia era: a Bayesian approach to detection and parameter recovery
• Rigorous treatment of barycentric stellar motion: Perspective and light-time effects in astrometric and radial velocity data
• The kinematic signature of the Galactic warp in Gaia DR1 - I. The Hipparcos subsample
• Determining the mass of the planetary candidate HD 114762 b using Gaia
• Gaia astrometry for stars with too few observations - a Bayesian approach
• Unbiased TGAS$\times$LAMOST distances and the role of binarity
• Very Low-Mass Stars and Brown Dwarfs in Upper Scorpius using Gaia DR1: Mass Function, Disks and Kinematics
• The SOPHIE search for northern extrasolar planets - XII. Three giant planets suitable for astrometric mass determination with Gaia
• Quasars can be used to verify the parallax zero-point of the Tycho-Gaia Astrometric Solution
• Simulation of CSSTs astrometric capability
• A Global Astrometric Solution for Pan-STARRS referenced to ICRF2
• The Possible Astrometric Signature of a Planetary-mass Companion to the Nearby Young Star TW Piscis Austrini (Fomalhaut B): Constraints from Astrometry, Radial Velocities, and Direct Imaging
• Analysis of the Bayesian Cramer-Rao lower bound in astrometry: Studying the impact of prior information in the location of an object
• Detection of a low-mass stellar companion to the accelerating A2IV star HR 1645
• Δμ Binaries among Stars with Large Proper Motions
• Astrometric radial velocities for nearby stars
• htof: A new open-source tool for analyzing Hipparcos, Gaia, and future astrometric missions