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Gaia Data Release 1 Astrometry: one billion positions, two million proper motions and parallaxes

Lindegren, L. and Joliet, E. (2016) Gaia Data Release 1 Astrometry: one billion positions, two million proper motions and parallaxes. Astronomy and Astrophysics, 595 . Art. No. A4. ISSN 0004-6361.

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Context. Gaia Data Release 1 (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, and validation of the results. Methods. For stars in common with the Hipparcos and Tycho-2 catalogues, complete astrometric single-star solutions are obtained by incorporating positional information from the earlier catalogues. For other stars only their positions are obtained, essentially by neglecting their proper motions and parallaxes. The results are validated by an analysis of the residuals, through special validation runs, and by comparison with external data. Results. For about two million of the brighter stars (down to magnitude ~11.5) we obtain positions, parallaxes, and proper motions to Hipparcos-type precision or better. For these stars, systematic errors depending for example on position and colour are at a level of ± 0.3 milliarcsecond (mas). For the remaining stars we obtain positions at epoch J2015.0 accurate to ~10 mas. Positions and proper motions are given in a reference frame that is aligned with the International Celestial Reference Frame (ICRF) to better than 0.1 mas at epoch J2015.0, and non-rotating with respect to ICRF to within 0.03 mas yr^(-1). The Hipparcos reference frame is found to rotate with respect to the Gaia DR1 frame at a rate of 0.24 mas yr^(-1). Conclusions. Based on less than a quarter of the nominal mission length and on very provisional and incomplete calibrations, the quality and completeness of the astrometric data in Gaia DR1 are far from what is expected for the final mission products. The present results nevertheless represent a huge improvement in the available fundamental stellar data and practical definition of the optical reference frame.

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Additional Information:© ESO, 2016. Received: 14 April 2016 Accepted: 29 June 2016 This work has made use of data from the ESA space mission Gaia, processed by the Gaia Data Processing and Analysis Consortium (DPAC). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The Gaia mission website is The authors are members of the Gaia DPAC. This work has been supported by: MINECO (Spanish Ministry of Economy) – FEDER through grant ESP2013-48318-C2-1-R and ESP2014-55996-C2-1-R and MDM-2014-0369 of ICCUB (Unidad de Excelencia “María de Maeztu”); the Netherlands Research School for Astronomy (NOVA); the German Aerospace Agency DLR under grants 50QG0501, 50QG1401 50QG0601, 50QG0901 and 50QG1402; the European Space Agency in the framework of the Gaia project; the Agenzia Spaziale Italiana (ASI) through grants ASI I/037/08/0, ASI I/058/10/0, ASI 2014-025-R.0, and ASI 2014-025-R.1.2015 and the Istituto Nazionale di AstroFisica (INAF); the Swedish National Space Board; the United Kingdom Space Agency; the Centre National d’Études Spatiales (CNES); Fundação para a Ciência e a Tecnologia through the contract Ciência2007 and project grant PTDC/CTE-SPA/118692/2010. We thank the Centre for Information Services and High Performance Computing (ZIH) at TU Dresden for generous allocations of computer time. This research has profited significantly from the services of the Centre de Données Astronomiques de Strasbourg, CDS (SIMBAD/VizieR/Aladin). Our work was eased considerably by the use of the astronomy-oriented data handling and visualisation software TOPCAT (Taylor 2005). We gratefully acknowledge its author, Mark Taylor, for providing support and implementing additional features for our needs. In addition to the authors of this work there are many other people who have made valuable contributions to Gaia’s astrometric reduction. Among these, we want to specifically mention Sebastian Els, Michael Perryman, Floor van Leeuwen, and the former members of the Gaia core processing team who have meanwhile moved on to other projects. We thank the anonymous referee for constructive comments on the original version of the manuscript.
Funding AgencyGrant Number
MINECO (Spanish Ministry of Economy)UNSPECIFIED
ICCUB (Unidad de Excelencia “María de Maeztu”)MDM-2014-0369
Netherlands Research School for Astronomy (NOVA)UNSPECIFIED
Deutschen Zentrum für Luft- und Raumfahrt (DLR)50QG0501
Deutschen Zentrum für Luft- und Raumfahrt (DLR)50QG1401
Deutschen Zentrum für Luft- und Raumfahrt (DLR)50QG0601
Deutschen Zentrum für Luft- und Raumfahrt (DLR)50QG0901
Deutschen Zentrum für Luft- und Raumfahrt (DLR)50QG1402
European Space Agency (ESA)UNSPECIFIED
Agenzia Spaziale Italiana (ASI)ASI I/037/08/0
Agenzia Spaziale Italiana (ASI)ASI I/058/10/0
Agenzia Spaziale Italiana (ASI)ASI 2014-025-R.0
Agenzia Spaziale Italiana (ASI)ASI 2014-025-R.1.2015
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Swedish National Space Board (SNSB)UNSPECIFIED
United Kingdom Space Agency (UKSA)UNSPECIFIED
Centre National d’Études Spatiales (CNES)UNSPECIFIED
Fundação para a Ciência e a TecnologiaCiência2007
Fundação para a Ciência e a TecnologiaPTDC/CTE-SPA/118692/2010
Subject Keywords:astrometry parallaxes proper motions methods: data analysis space vehicles: instruments reference systems
Record Number:CaltechAUTHORS:20170113-074520929
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Official Citation:Gaia Data Release 1 - Astrometry: one billion positions, two million proper motions and parallaxes L. Lindegren, U. Lammers, U. Bastian, J. Hernández, S. Klioner, D. Hobbs, A. Bombrun, D. Michalik, M. Ramos-Lerate, A. Butkevich, G. Comoretto, E. Joliet, B. Holl, A. Hutton, P. Parsons, H. Steidelmüller, U. Abbas, M. Altmann, A. Andrei, S. Anton, N. Bach, C. Barache, U. Becciani, J. Berthier, L. Bianchi, M. Biermann, S. Bouquillon, G. Bourda, T. Brüsemeister, B. Bucciarelli, D. Busonero, T. Carlucci, J. Castañeda, P. Charlot, M. Clotet, M. Crosta, M. Davidson, F. de Felice, R. Drimmel, C. Fabricius, A. Fienga, F. Figueras, E. Fraile, M. Gai, N. Garralda, R. Geyer, J. J. González-Vidal, R. Guerra, N. C. Hambly, M. Hauser, S. Jordan, M. G. Lattanzi, H. Lenhardt, S. Liao, W. Löffler, P. J. McMillan, F. Mignard, A. Mora, R. Morbidelli, J. Portell, A. Riva, M. Sarasso, I. Serraller, H. Siddiqui, R. Smart, A. Spagna, U. Stampa, I. Steele, F. Taris, J. Torra, W. van Reeven, A. Vecchiato, S. Zschocke, J. de Bruijne, G. Gracia, F. Raison, T. Lister, J. Marchant, R. Messineo, M. Soffel, J. Osorio, A. de Torres and W. O’Mullane A&A, 595 (2016) A4 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73481
Deposited By: Ruth Sustaita
Deposited On:18 Jan 2017 21:14
Last Modified:18 Jan 2017 21:14

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