A.-M. Janotto

TL;DR: Gaia as discussed by the authors is a cornerstone mission in the science programme of the European Space Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept was changed to a direct-imaging approach.

TL;DR: In this article, the authors describe the data analysis system put together by the Gaia consortium to classify these objects and to infer their astrophysical properties using the satellite's data, covering single stars, (unresolved) binary stars, quasars, and galaxies, all covering a wide parameter space.

TL;DR: The first Gaia Data Release contains the Tycho-Gaia Astrometric Solution (TGAS) component by means of the astrometric data for open clusters as mentioned in this paper, which is a subset of about 2 million stars for which, besides the position and photometry, the proper motion and parallax are calculated using Hipparcos and Tycho 2 positions in 1991.

TL;DR: In this article, the first parallax measurements of the primary standard candles of the cosmological distance ladder, that involve astrometry collected by Gaia during the initial 14 months of science operation, are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS).

TL;DR: In this paper, the first parallax measurements of the primary standard candles of the cosmological distance ladder, that involve astrometry collected by Gaia during the initial 14 months of science operation, are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS).