• DOI:10.1051/0004-6361/201832727
• Corpus ID: 54497421

Gaia Data Release 2

@article{Lindegren2018GaiaDR,
  title={Gaia Data Release 2},
  author={Lennart Lindegren and J. Hernandez and Alex Bombrun and Sergei A. Klioner and Ulrich Bastian and Mercedes Ramos-lerate and Anthony D. Torres and H. Steidelmuller and Craig Stephenson and David Hobbs and Uwe Lammers and Michael Biermann and R. Geyer and T. Hilger and Daniel Michalik and Ulrike Stampa and Paul J McMillan and Javier Casta{\~n}eda and Marcial Clotet and Gabriele Comoretto and Michael Davidson and Claus Fabricius and G. Gracia and Nigel C. Hambly and Alexander Hutton and Andr{\'e} Mora and Jordi Portell and Floor van Leeuwen and Ummi Abbas and Asier Abreu and Martin Altmann and A. H. Andrei and E. Anglada and L. Balaguer-N{\'u}{\~n}ez and Christophe Barache and Ugo Becciani and Stefano Bertone and Luca Bianchi and S{\'e}bastien Bouquillon and G{\'e}raldine Bourda and T. Brusemeister and Beatrice Bucciarelli and Deborah Busonero and Raffaella Buzzi and Rossella Cancelliere and T. Carlucci and Patrick Charlot and N. Cheek and Mariateresa Crosta and C. M. Crowley and Jos H.J. de Bruijne and Fernando de Felice and Ronald Drimmel and Pilar Esquej and A. Fienga and Eduardo Miguel Gonz{\'a}lez Fraile and Mario Gai and Nora Garralda and Juan Jos{\'e} Gonz{\'a}lez-Vidal and R. Guerra and Marcus Hauser and W. Hofmann and Berry Holl and Stefan Jordan and Mario Gilberto Lattanzi and Helmut Lenhardt and Shi-long Liao and Enrico Licata and Tim Lister and Wolfgang Loffler and Jonathan M. Marchant and Juan Manuel Mart{\'i}n-Fleitas and Rosario Messineo and François Mignard and Roberto Morbidelli and E. Poggio and Alberto Riva and Nick Rowell and E. Salguero and M. Sarasso and Eva Sciacca and H. Siddiqui and R. L. Smart and Alessandro Spagna and Iain A. Steele and François Taris and Jordi Torra and Arjen van Elteren and Wouter van Reeven and Alberto Vecchiato},
  journal={Astronomy \& Astrophysics},
  year={2018}
}

• L. Lindegren, J. Hernandez, +87 authors A. Vecchiato
• Published 25 April 2018
• Physics
• Astronomy & Astrophysics

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 the first 22 months of its operational phase.
Aims. We describe the input data, models, and processing used for the astrometric content of Gaia DR2, and the validation of these resultsperformed within the astrometry task.
Methods. Some 320 billion centroid positions from the pre-processed astrometric CCD observations were used to estimate the five astrometric parameters (positions, parallaxes, and proper motions) for 1332 million sources, and approximate positions at the reference epoch J2015.5 for an additional 361 million mostly faint sources. These data were calculated in two steps. First, the satellite attitude and the astrometric calibration parameters of the CCDs were obtained in an astrometric global iterative solution for 16 million selected sources, using about 1% of the input data. This primary solution was tied to the extragalactic International Celestial Reference System (ICRS) by means of quasars. The resulting attitude and calibration were then used to calculate the astrometric parameters of all the sources. Special validation solutions were used to characterise the random and systematic errors in parallax and proper motion.
Results. For the sources with five-parameter astrometric solutions, the median uncertainty in parallax and position at the reference epoch J2015.5 is about 0.04 mas for bright (G < 14 mag) sources, 0.1 mas at G = 17 mag, and 0.7 masat G = 20 mag. In the proper motion components the corresponding uncertainties are 0.05, 0.2, and 1.2 mas yr−1, respectively.The optical reference frame defined by Gaia DR2 is aligned with ICRS and is non-rotating with respect to the quasars to within 0.15 mas yr−1. From the quasars and validation solutions we estimate that systematics in the parallaxes depending on position, magnitude, and colour are generally below 0.1 mas, but the parallaxes are on the whole too small by about 0.03 mas. Significant spatial correlations of up to 0.04 mas in parallax and 0.07 mas yr−1 in proper motion are seen on small (< 1 deg) and intermediate (20 deg) angular scales. Important statistics and information for the users of the Gaia DR2 astrometry are given in the appendices.