Gaia Data Release 2. Summary of the contents and survey properties

<!DOCTYPE html>     <html class="no-js" lang="en">  <head> <title>Gaia Data Release 2. Summary of the contents and survey properties - NASA/ADS</title>  <link rel="apple-touch-icon" sizes="180x180" href="//styles/favicon/apple-touch-icon.png" /> <link rel="icon" type="image/png" sizes="32x32" href="//styles/favicon/favicon-32x32.png" /> <link rel="icon" type="image/png" sizes="16x16" href="//styles/favicon/favicon-16x16.png" /> <link rel="manifest" href="//styles/favicon/site.webmanifest" /> <link rel="mask-icon" href="//styles/favicon/safari-pinned-tab.svg" color="#5bbad5" /> <meta name="apple-mobile-web-app-title" content="NASA ADS" /> <meta name="application-name" content="NASA ADS" /> <meta name="msapplication-TileColor" content="#ffc40d" /> <meta name="theme-color" content="#ffffff" />  <link rel="stylesheet" href="/styles/css/styles.css"> <meta name="robots" content="noarchive"> <link rel="canonical" href="http://ui.adsabs.harvard.edu/abs/2018A&A...616A...1G/abstract"/> <meta name="description" content="Context. We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources brighter than magnitude 21. In addition epoch astrometry and photometry are provided for a modest sample of minor planets in the solar system. <BR /> Aims: A summary of the contents of Gaia DR2 is presented, accompanied by a discussion on the differences with respect to Gaia DR1 and an overview of the main limitations which are still present in the survey. Recommendations are made on the responsible use of Gaia DR2 results. <BR /> Methods: The raw data collected with the Gaia instruments during the first 22 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into this second data release, which represents a major advance with respect to Gaia DR1 in terms of completeness, performance, and richness of the data products. <BR /> Results: Gaia DR2 contains celestial positions and the apparent brightness in G for approximately 1.7 billion sources. For 1.3 billion of those sources, parallaxes and proper motions are in addition available. The sample of sources for which variability information is provided is expanded to 0.5 million stars. This data release contains four new elements: broad-band colour information in the form of the apparent brightness in the G<SUB>BP</SUB> (330-680 nm) and G<SUB>RP</SUB> (630-1050 nm) bands is available for 1.4 billion sources; median radial velocities for some 7 million sources are presented; for between 77 and 161 million sources estimates are provided of the stellar effective temperature, extinction, reddening, and radius and luminosity; and for a pre-selected list of 14 000 minor planets in the solar system epoch astrometry and photometry are presented. Finally, Gaia DR2 also represents a new materialisation of the celestial reference frame in the optical, the Gaia-CRF2, which is the first optical reference frame based solely on extragalactic sources. There are notable changes in the photometric system and the catalogue source list with respect to Gaia DR1, and we stress the need to consider the two data releases as independent. <BR /> Conclusions: Gaia DR2 represents a major achievement for the Gaia mission, delivering on the long standing promise to provide parallaxes and proper motions for over 1 billion stars, and representing a first step in the availability of complementary radial velocity and source astrophysical information for a sample of stars in the Gaia survey which covers a very substantial fraction of the volume of our galaxy.">  <meta property="og:type" content="article"> <meta property="og:title" content="Gaia Data Release 2. Summary of the contents and survey properties"> <meta property="og:site_name" content="NASA/ADS"> <meta property="og:description" content="Context. We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources brighter than magnitude 21. In addition epoch astrometry and photometry are provided for a modest sample of minor planets in the solar system. <BR /> Aims: A summary of the contents of Gaia DR2 is presented, accompanied by a discussion on the differences with respect to Gaia DR1 and an overview of the main limitations which are still present in the survey. Recommendations are made on the responsible use of Gaia DR2 results. <BR /> Methods: The raw data collected with the Gaia instruments during the first 22 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into this second data release, which represents a major advance with respect to Gaia DR1 in terms of completeness, performance, and richness of the data products. <BR /> Results: Gaia DR2 contains celestial positions and the apparent brightness in G for approximately 1.7 billion sources. For 1.3 billion of those sources, parallaxes and proper motions are in addition available. The sample of sources for which variability information is provided is expanded to 0.5 million stars. This data release contains four new elements: broad-band colour information in the form of the apparent brightness in the G<SUB>BP</SUB> (330-680 nm) and G<SUB>RP</SUB> (630-1050 nm) bands is available for 1.4 billion sources; median radial velocities for some 7 million sources are presented; for between 77 and 161 million sources estimates are provided of the stellar effective temperature, extinction, reddening, and radius and luminosity; and for a pre-selected list of 14 000 minor planets in the solar system epoch astrometry and photometry are presented. Finally, Gaia DR2 also represents a new materialisation of the celestial reference frame in the optical, the Gaia-CRF2, which is the first optical reference frame based solely on extragalactic sources. There are notable changes in the photometric system and the catalogue source list with respect to Gaia DR1, and we stress the need to consider the two data releases as independent. <BR /> Conclusions: Gaia DR2 represents a major achievement for the Gaia mission, delivering on the long standing promise to provide parallaxes and proper motions for over 1 billion stars, and representing a first step in the availability of complementary radial velocity and source astrophysical information for a sample of stars in the Gaia survey which covers a very substantial fraction of the volume of our galaxy."> <meta property="og:url" content="https://ui.adsabs.harvard.edu/abs/2018A&A...616A...1G/abstract"> <meta property="og:image" content="https://ui.adsabs.harvard.edu/styles/img/transparent_logo.svg"> <meta property="article:published_time" content="08/2018"> <meta property="article:author" content="Gaia Collaboration"> <meta property="article:author" content="Brown, A. G. 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M."> <meta name="dc.creator" content="Siopis, C."> <meta name="dc.creator" content="Smith, M."> <meta name="dc.creator" content="Sozzetti, A."> <meta name="dc.creator" content="S眉veges, M."> <meta name="dc.creator" content="Torra, J."> <meta name="dc.creator" content="van Reeven, W."> <meta name="dc.creator" content="Abbas, U."> <meta name="dc.creator" content="Abreu Aramburu, A."> <meta name="dc.creator" content="Accart, S."> <meta name="dc.creator" content="Aerts, C."> <meta name="dc.creator" content="Altavilla, G."> <meta name="dc.creator" content="脕lvarez, M. A."> <meta name="dc.creator" content="Alvarez, R."> <meta name="dc.creator" content="Alves, J."> <meta name="dc.creator" content="Anderson, R. I."> <meta name="dc.creator" content="Andrei, A. H."> <meta name="dc.creator" content="Anglada Varela, E."> <meta name="dc.creator" content="Antiche, E."> <meta name="dc.creator" content="Antoja, T."> <meta name="dc.creator" content="Arcay, B."> <meta name="dc.creator" content="Astraatmadja, T. L."> <meta name="dc.creator" content="Bach, N."> <meta name="dc.creator" content="Baker, S. G."> <meta name="dc.creator" content="Balaguer-N煤帽ez, L."> <meta name="dc.creator" content="Balm, P."> <meta name="dc.creator" content="Barache, C."> <meta name="dc.creator" content="Barata, C."> <meta name="dc.creator" content="Barbato, D."> <meta name="dc.creator" content="Barblan, F."> <meta name="dc.creator" content="Barklem, P. S."> <meta name="dc.creator" content="Barrado, D."> <meta name="dc.creator" content="Barros, M."> <meta name="dc.creator" content="Barstow, M. A."> <meta name="dc.creator" content="Bartholom茅 Mu帽oz, S."> <meta name="dc.creator" content="Bassilana, J. -L."> <meta name="dc.creator" content="Becciani, U."> <meta name="dc.creator" content="Bellazzini, M."> <meta name="dc.creator" content="Berihuete, A."> <meta name="dc.creator" content="Bertone, S."> <meta name="dc.creator" content="Bianchi, L."> <meta name="dc.creator" content="Bienaym茅, O."> <meta name="dc.creator" content="Blanco-Cuaresma, S."> <meta name="dc.creator" content="Boch, T."> <meta name="dc.creator" content="Boeche, C."> <meta name="dc.creator" content="Bombrun, A."> <meta name="dc.creator" content="Borrachero, R."> <meta name="dc.creator" content="Bossini, D."> <meta name="dc.creator" content="Bouquillon, S."> <meta name="dc.creator" content="Bourda, G."> <meta name="dc.creator" content="Bragaglia, A."> <meta name="dc.creator" content="Bramante, L."> <meta name="dc.creator" content="Breddels, M. A."> <meta name="dc.creator" content="Bressan, A."> <meta name="dc.creator" content="Brouillet, N."> <meta name="dc.creator" content="Br眉semeister, T."> <meta name="dc.creator" content="Brugaletta, E."> <meta name="dc.creator" content="Bucciarelli, B."> <meta name="dc.creator" content="Burlacu, A."> <meta name="dc.creator" content="Busonero, D."> <meta name="dc.creator" content="Butkevich, A. G."> <meta name="dc.creator" content="Buzzi, R."> <meta name="dc.creator" content="Caffau, E."> <meta name="dc.creator" content="Cancelliere, R."> <meta name="dc.creator" content="Cannizzaro, G."> <meta name="dc.creator" content="Cantat-Gaudin, T."> <meta name="dc.creator" content="Carballo, R."> <meta name="dc.creator" content="Carlucci, T."> <meta name="dc.creator" content="Carrasco, J. M."> <meta name="dc.creator" content="Casamiquela, L."> <meta name="dc.creator" content="Castellani, M."> <meta name="dc.creator" content="Castro-Ginard, A."> <meta name="dc.creator" content="Charlot, P."> <meta name="dc.creator" content="Chemin, L."> <meta name="dc.creator" content="Chiavassa, A."> <meta name="dc.creator" content="Cocozza, G."> <meta name="dc.creator" content="Costigan, G."> <meta name="dc.creator" content="Cowell, S."> <meta name="dc.creator" content="Crifo, F."> <meta name="dc.creator" content="Crosta, M."> <meta name="dc.creator" content="Crowley, C."> <meta name="dc.creator" content="Cuypers, J."> <meta name="dc.creator" content="Dafonte, C."> <meta name="dc.creator" content="Damerdji, Y."> <meta name="dc.creator" content="Dapergolas, A."> <meta name="dc.creator" content="David, P."> <meta name="dc.creator" content="David, M."> <meta name="dc.creator" content="de Laverny, P."> <meta name="dc.creator" content="De Luise, F."> <meta name="dc.creator" content="De March, R."> <meta name="dc.creator" content="de Martino, D."> <meta name="dc.creator" content="de Souza, R."> <meta name="dc.creator" content="de Torres, A."> <meta name="dc.creator" content="Debosscher, J."> <meta name="dc.creator" content="del Pozo, E."> <meta name="dc.creator" content="Delbo, M."> <meta name="dc.creator" content="Delgado, A."> <meta name="dc.creator" content="Delgado, H. E."> <meta name="dc.creator" content="Di Matteo, P."> <meta name="dc.creator" content="Diakite, S."> <meta name="dc.creator" content="Diener, C."> <meta name="dc.creator" content="Distefano, E."> <meta name="dc.creator" content="Dolding, C."> <meta name="dc.creator" content="Drazinos, P."> <meta name="dc.creator" content="Dur谩n, J."> <meta name="dc.creator" content="Edvardsson, B."> <meta name="dc.creator" content="Enke, H."> <meta name="dc.creator" content="Eriksson, K."> <meta name="dc.creator" content="Esquej, P."> <meta name="dc.creator" content="Eynard Bontemps, G."> <meta name="dc.creator" content="Fabre, C."> <meta name="dc.creator" content="Fabrizio, M."> <meta name="dc.creator" content="Faigler, S."> <meta name="dc.creator" content="Falc茫o, A. J."> <meta name="dc.creator" content="Farr脿s Casas, M."> <meta name="dc.creator" content="Federici, L."> <meta name="dc.creator" content="Fedorets, G."> <meta name="dc.creator" content="Fernique, P."> <meta name="dc.creator" content="Figueras, F."> <meta name="dc.creator" content="Filippi, F."> <meta name="dc.creator" content="Findeisen, K."> <meta name="dc.creator" content="Fonti, A."> <meta name="dc.creator" content="Fraile, E."> <meta name="dc.creator" content="Fraser, M."> <meta name="dc.creator" content="Fr茅zouls, B."> <meta name="dc.creator" content="Gai, M."> <meta name="dc.creator" content="Galleti, S."> <meta name="dc.creator" content="Garabato, D."> <meta name="dc.creator" content="Garc铆a-Sedano, F."> <meta name="dc.creator" content="Garofalo, A."> <meta name="dc.creator" content="Garralda, N."> <meta name="dc.creator" content="Gavel, A."> <meta name="dc.creator" content="Gavras, P."> <meta name="dc.creator" content="Gerssen, J."> <meta name="dc.creator" content="Geyer, R."> <meta name="dc.creator" content="Giacobbe, P."> <meta name="dc.creator" content="Gilmore, G."> <meta name="dc.creator" content="Girona, S."> <meta name="dc.creator" content="Giuffrida, G."> <meta name="dc.creator" content="Glass, F."> <meta name="dc.creator" content="Gomes, M."> <meta name="dc.creator" content="Granvik, M."> <meta name="dc.creator" content="Gueguen, A."> <meta name="dc.creator" content="Guerrier, A."> <meta name="dc.creator" content="Guiraud, J."> <meta name="dc.creator" content="Guti茅rrez-S谩nchez, R."> <meta name="dc.creator" content="Haigron, R."> <meta name="dc.creator" content="Hatzidimitriou, D."> <meta name="dc.creator" content="Hauser, M."> <meta name="dc.creator" content="Haywood, M."> <meta name="dc.creator" content="Heiter, U."> <meta name="dc.creator" content="Helmi, A."> <meta name="dc.creator" content="Heu, J."> <meta name="dc.creator" content="Hilger, T."> <meta name="dc.creator" content="Hobbs, D."> <meta name="dc.creator" content="Hofmann, W."> <meta name="dc.creator" content="Holland, G."> <meta name="dc.creator" content="Huckle, H. E."> <meta name="dc.creator" content="Hypki, A."> <meta name="dc.creator" content="Icardi, V."> <meta name="dc.creator" content="Jan脽en, K."> <meta name="dc.creator" content="Jevardat de Fombelle, G."> <meta name="dc.creator" content="Jonker, P. G."> <meta name="dc.creator" content="Juh谩sz, 脕. L."> <meta name="dc.creator" content="Julbe, F."> <meta name="dc.creator" content="Karampelas, A."> <meta name="dc.creator" content="Kewley, A."> <meta name="dc.creator" content="Klar, J."> <meta name="dc.creator" content="Kochoska, A."> <meta name="dc.creator" content="Kohley, R."> <meta name="dc.creator" content="Kolenberg, K."> <meta name="dc.creator" content="Kontizas, M."> <meta name="dc.creator" content="Kontizas, E."> <meta name="dc.creator" content="Koposov, S. E."> <meta name="dc.creator" content="Kordopatis, G."> <meta name="dc.creator" content="Kostrzewa-Rutkowska, Z."> <meta name="dc.creator" content="Koubsky, P."> <meta name="dc.creator" content="Lambert, S."> <meta name="dc.creator" content="Lanza, A. F."> <meta name="dc.creator" content="Lasne, Y."> <meta name="dc.creator" content="Lavigne, J. -B."> <meta name="dc.creator" content="Le Fustec, Y."> <meta name="dc.creator" content="Le Poncin-Lafitte, C."> <meta name="dc.creator" content="Lebreton, Y."> <meta name="dc.creator" content="Leccia, S."> <meta name="dc.creator" content="Leclerc, N."> <meta name="dc.creator" content="Lecoeur-Taibi, I."> <meta name="dc.creator" content="Lenhardt, H."> <meta name="dc.creator" content="Leroux, F."> <meta name="dc.creator" content="Liao, S."> <meta name="dc.creator" content="Licata, E."> <meta name="dc.creator" content="Lindstr酶m, H. E. P."> <meta name="dc.creator" content="Lister, T. A."> <meta name="dc.creator" content="Livanou, E."> <meta name="dc.creator" content="Lobel, A."> <meta name="dc.creator" content="L贸pez, M."> <meta name="dc.creator" content="Managau, S."> <meta name="dc.creator" content="Mann, R. G."> <meta name="dc.creator" content="Mantelet, G."> <meta name="dc.creator" content="Marchal, O."> <meta name="dc.creator" content="Marchant, J. M."> <meta name="dc.creator" content="Marconi, M."> <meta name="dc.creator" content="Marinoni, S."> <meta name="dc.creator" content="Marschalk贸, G."> <meta name="dc.creator" content="Marshall, D. J."> <meta name="dc.creator" content="Martino, M."> <meta name="dc.creator" content="Marton, G."> <meta name="dc.creator" content="Mary, N."> <meta name="dc.creator" content="Massari, D."> <meta name="dc.creator" content="Matijevi膷, G."> <meta name="dc.creator" content="Mazeh, T."> <meta name="dc.creator" content="McMillan, P. J."> <meta name="dc.creator" content="Messina, S."> <meta name="dc.creator" content="Michalik, D."> <meta name="dc.creator" content="Millar, N. R."> <meta name="dc.creator" content="Molina, D."> <meta name="dc.creator" content="Molinaro, R."> <meta name="dc.creator" content="Moln谩r, L."> <meta name="dc.creator" content="Montegriffo, P."> <meta name="dc.creator" content="Mor, R."> <meta name="dc.creator" content="Morbidelli, R."> <meta name="dc.creator" content="Morel, T."> <meta name="dc.creator" content="Morris, D."> <meta name="dc.creator" content="Mulone, A. F."> <meta name="dc.creator" content="Muraveva, T."> <meta name="dc.creator" content="Musella, I."> <meta name="dc.creator" content="Nelemans, G."> <meta name="dc.creator" content="Nicastro, L."> <meta name="dc.creator" content="Noval, L."> <meta name="dc.creator" content="O'Mullane, W."> <meta name="dc.creator" content="Ord茅novic, C."> <meta name="dc.creator" content="Ord贸帽ez-Blanco, D."> <meta name="dc.creator" content="Osborne, P."> <meta name="dc.creator" content="Pagani, C."> <meta name="dc.creator" content="Pagano, I."> <meta name="dc.creator" content="Pailler, F."> <meta name="dc.creator" content="Palacin, H."> <meta name="dc.creator" content="Palaversa, L."> <meta name="dc.creator" content="Panahi, A."> <meta name="dc.creator" content="Pawlak, M."> <meta name="dc.creator" content="Piersimoni, A. M."> <meta name="dc.creator" content="Pineau, F. -X."> <meta name="dc.creator" content="Plachy, E."> <meta name="dc.creator" content="Plum, G."> <meta name="dc.creator" content="Poggio, E."> <meta name="dc.creator" content="Poujoulet, E."> <meta name="dc.creator" content="Pr拧a, A."> <meta name="dc.creator" content="Pulone, L."> <meta name="dc.creator" content="Racero, E."> <meta name="dc.creator" content="Ragaini, S."> <meta name="dc.creator" content="Rambaux, N."> <meta name="dc.creator" content="Ramos-Lerate, M."> <meta name="dc.creator" content="Regibo, S."> <meta name="dc.creator" content="Reyl茅, C."> <meta name="dc.creator" content="Riclet, F."> <meta name="dc.creator" content="Ripepi, V."> <meta name="dc.creator" content="Riva, A."> <meta name="dc.creator" content="Rivard, A."> <meta name="dc.creator" content="Rixon, G."> <meta name="dc.creator" content="Roegiers, T."> <meta name="dc.creator" content="Roelens, M."> <meta name="dc.creator" content="Romero-G贸mez, M."> <meta name="dc.creator" content="Rowell, N."> <meta name="dc.creator" content="Royer, F."> <meta name="dc.creator" content="Ruiz-Dern, L."> <meta name="dc.creator" content="Sadowski, G."> <meta name="dc.creator" content="Sagrist脿 Sell茅s, T."> <meta name="dc.creator" content="Sahlmann, J."> <meta name="dc.creator" content="Salgado, J."> <meta name="dc.creator" content="Salguero, E."> <meta name="dc.creator" content="Sanna, N."> <meta name="dc.creator" content="Santana-Ros, T."> <meta name="dc.creator" content="Sarasso, M."> <meta name="dc.creator" content="Savietto, H."> <meta name="dc.creator" content="Schultheis, M."> <meta name="dc.creator" content="Sciacca, E."> <meta name="dc.creator" content="Segol, M."> <meta name="dc.creator" content="Segovia, J. C."> <meta name="dc.creator" content="S茅gransan, D."> <meta name="dc.creator" content="Shih, I. -C."> <meta name="dc.creator" content="Siltala, L."> <meta name="dc.creator" content="Silva, A. F."> <meta name="dc.creator" content="Smart, R. L."> <meta name="dc.creator" content="Smith, K. W."> <meta name="dc.creator" content="Solano, E."> <meta name="dc.creator" content="Solitro, F."> <meta name="dc.creator" content="Sordo, R."> <meta name="dc.creator" content="Soria Nieto, S."> <meta name="dc.creator" content="Souchay, J."> <meta name="dc.creator" content="Spagna, A."> <meta name="dc.creator" content="Spoto, F."> <meta name="dc.creator" content="Stampa, U."> <meta name="dc.creator" content="Steele, I. A."> <meta name="dc.creator" content="Steidelm眉ller, H."> <meta name="dc.creator" content="Stephenson, C. A."> <meta name="dc.creator" content="Stoev, H."> <meta name="dc.creator" content="Suess, F. F."> <meta name="dc.creator" content="Surdej, J."> <meta name="dc.creator" content="Szabados, L."> <meta name="dc.creator" content="Szegedi-Elek, E."> <meta name="dc.creator" content="Tapiador, D."> <meta name="dc.creator" content="Taris, F."> <meta name="dc.creator" content="Tauran, G."> <meta name="dc.creator" content="Taylor, M. B."> <meta name="dc.creator" content="Teixeira, R."> <meta name="dc.creator" content="Terrett, D."> <meta name="dc.creator" content="Teyssandier, P."> <meta name="dc.creator" content="Thuillot, W."> <meta name="dc.creator" content="Titarenko, A."> <meta name="dc.creator" content="Torra Clotet, F."> <meta name="dc.creator" content="Turon, C."> <meta name="dc.creator" content="Ulla, A."> <meta name="dc.creator" content="Utrilla, E."> <meta name="dc.creator" content="Uzzi, S."> <meta name="dc.creator" content="Vaillant, M."> <meta name="dc.creator" content="Valentini, G."> <meta name="dc.creator" content="Valette, V."> <meta name="dc.creator" content="van Elteren, A."> <meta name="dc.creator" content="Van Hemelryck, E."> <meta name="dc.creator" content="van Leeuwen, M."> <meta name="dc.creator" content="Vaschetto, M."> <meta name="dc.creator" content="Vecchiato, A."> <meta name="dc.creator" content="Veljanoski, J."> <meta name="dc.creator" content="Viala, Y."> <meta name="dc.creator" content="Vicente, D."> <meta name="dc.creator" content="Vogt, S."> <meta name="dc.creator" content="von Essen, C."> <meta name="dc.creator" content="Voss, H."> <meta name="dc.creator" content="Votruba, V."> <meta name="dc.creator" content="Voutsinas, S."> <meta name="dc.creator" content="Walmsley, G."> <meta name="dc.creator" content="Weiler, M."> <meta name="dc.creator" content="Wertz, O."> <meta name="dc.creator" content="Wevers, T."> <meta name="dc.creator" content="Wyrzykowski, 艁."> <meta name="dc.creator" content="Yoldas, A."> <meta name="dc.creator" content="沤erjal, M."> <meta name="dc.creator" content="Ziaeepour, H."> <meta name="dc.creator" content="Zorec, J."> <meta name="dc.creator" content="Zschocke, S."> <meta name="dc.creator" content="Zucker, S."> <meta name="dc.creator" content="Zurbach, C."> <meta name="dc.creator" content="Zwitter, T.">  <meta name="twitter:card" content="summary_large_image"/> <meta name="twitter:description" content="Context. We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources brighter than magnitude 21. In addition epoch astrometry and photometry are provided for a modest sample of minor planets in the solar system. <BR /> Aims: A summary of the contents of Gaia DR2 is presented, accompanied by a discussion on the differences with respect to Gaia DR1 and an overview of the main limitations which are still present in the survey. Recommendations are made on the responsible use of Gaia DR2 results. <BR /> Methods: The raw data collected with the Gaia instruments during the first 22 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into this second data release, which represents a major advance with respect to Gaia DR1 in terms of completeness, performance, and richness of the data products. <BR /> Results: Gaia DR2 contains celestial positions and the apparent brightness in G for approximately 1.7 billion sources. For 1.3 billion of those sources, parallaxes and proper motions are in addition available. The sample of sources for which variability information is provided is expanded to 0.5 million stars. This data release contains four new elements: broad-band colour information in the form of the apparent brightness in the G<SUB>BP</SUB> (330-680 nm) and G<SUB>RP</SUB> (630-1050 nm) bands is available for 1.4 billion sources; median radial velocities for some 7 million sources are presented; for between 77 and 161 million sources estimates are provided of the stellar effective temperature, extinction, reddening, and radius and luminosity; and for a pre-selected list of 14 000 minor planets in the solar system epoch astrometry and photometry are presented. Finally, Gaia DR2 also represents a new materialisation of the celestial reference frame in the optical, the Gaia-CRF2, which is the first optical reference frame based solely on extragalactic sources. There are notable changes in the photometric system and the catalogue source list with respect to Gaia DR1, and we stress the need to consider the two data releases as independent. <BR /> Conclusions: Gaia DR2 represents a major achievement for the Gaia mission, delivering on the long standing promise to provide parallaxes and proper motions for over 1 billion stars, and representing a first step in the availability of complementary radial velocity and source astrophysical information for a sample of stars in the Gaia survey which covers a very substantial fraction of the volume of our galaxy."/> <meta name="twitter:title" content="Gaia Data Release 2. 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Summary of the contents and survey properties <a href=""></a> </h2> <div id="authors-and-aff" class="s-authors-and-aff"> <ul class="list-inline"> <li class="author"><a href="/search/?q=author%3A%22Gaia+Collaboration%22">Gaia Collaboration</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Brown%2C+A.+G.+A.%22">Brown, A. G. A.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Vallenari%2C+A.%22">Vallenari, A.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Prusti%2C+T.%22">Prusti, T.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22de+Bruijne%2C+J.+H.+J.%22">de Bruijne, J. H. J.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Babusiaux%2C+C.%22">Babusiaux, C.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Bailer-Jones%2C+C.+A.+L.%22">Bailer-Jones, C. A. L.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Biermann%2C+M.%22">Biermann, M.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Evans%2C+D.+W.%22">Evans, D. W.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Eyer%2C+L.%22">Eyer, L.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Jansen%2C+F.%22">Jansen, F.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Jordi%2C+C.%22">Jordi, C.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Klioner%2C+S.+A.%22">Klioner, S. A.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Lammers%2C+U.%22">Lammers, U.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Lindegren%2C+L.%22">Lindegren, L.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Luri%2C+X.%22">Luri, X.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Mignard%2C+F.%22">Mignard, F.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Panem%2C+C.%22">Panem, C.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Pourbaix%2C+D.%22">Pourbaix, D.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Randich%2C+S.%22">Randich, S.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Sartoretti%2C+P.%22">Sartoretti, P.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Siddiqui%2C+H.+I.%22">Siddiqui, H. I.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Soubiran%2C+C.%22">Soubiran, C.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22van+Leeuwen%2C+F.%22">van Leeuwen, F.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Walton%2C+N.+A.%22">Walton, N. A.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Arenou%2C+F.%22">Arenou, F.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Bastian%2C+U.%22">Bastian, U.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Cropper%2C+M.%22">Cropper, M.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Drimmel%2C+R.%22">Drimmel, R.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Katz%2C+D.%22">Katz, D.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Lattanzi%2C+M.+G.%22">Lattanzi, M. G.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Bakker%2C+J.%22">Bakker, J.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Cacciari%2C+C.%22">Cacciari, C.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Casta%C3%B1eda%2C+J.%22">Casta帽eda, J.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Chaoul%2C+L.%22">Chaoul, L.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Cheek%2C+N.%22">Cheek, N.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22De+Angeli%2C+F.%22">De Angeli, F.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Fabricius%2C+C.%22">Fabricius, C.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Guerra%2C+R.%22">Guerra, R.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Holl%2C+B.%22">Holl, B.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Masana%2C+E.%22">Masana, E.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Messineo%2C+R.%22">Messineo, R.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Mowlavi%2C+N.%22">Mowlavi, N.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Nienartowicz%2C+K.%22">Nienartowicz, K.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Panuzzo%2C+P.%22">Panuzzo, P.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Portell%2C+J.%22">Portell, J.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Riello%2C+M.%22">Riello, M.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Seabroke%2C+G.+M.%22">Seabroke, G. M.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Tanga%2C+P.%22">Tanga, P.</a> </li>; <li class="author"><a href="/search/?q=author%3A%22Th%C3%A9venin%2C+F.%22">Th茅venin, F.</a> </li> <li> <em>and 404 more</em> </li> </ul> </div> <div class="s-abstract-text"> <h4 class="sr-only">Abstract</h4> <p> Context. We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources brighter than magnitude 21. In addition epoch astrometry and photometry are provided for a modest sample of minor planets in the solar system. <BR /> Aims: A summary of the contents of Gaia DR2 is presented, accompanied by a discussion on the differences with respect to Gaia DR1 and an overview of the main limitations which are still present in the survey. Recommendations are made on the responsible use of Gaia DR2 results. <BR /> Methods: The raw data collected with the Gaia instruments during the first 22 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into this second data release, which represents a major advance with respect to Gaia DR1 in terms of completeness, performance, and richness of the data products. <BR /> Results: Gaia DR2 contains celestial positions and the apparent brightness in G for approximately 1.7 billion sources. For 1.3 billion of those sources, parallaxes and proper motions are in addition available. The sample of sources for which variability information is provided is expanded to 0.5 million stars. This data release contains four new elements: broad-band colour information in the form of the apparent brightness in the G<SUB>BP</SUB> (330-680 nm) and G<SUB>RP</SUB> (630-1050 nm) bands is available for 1.4 billion sources; median radial velocities for some 7 million sources are presented; for between 77 and 161 million sources estimates are provided of the stellar effective temperature, extinction, reddening, and radius and luminosity; and for a pre-selected list of 14 000 minor planets in the solar system epoch astrometry and photometry are presented. Finally, Gaia DR2 also represents a new materialisation of the celestial reference frame in the optical, the Gaia-CRF2, which is the first optical reference frame based solely on extragalactic sources. There are notable changes in the photometric system and the catalogue source list with respect to Gaia DR1, and we stress the need to consider the two data releases as independent. <BR /> Conclusions: Gaia DR2 represents a major achievement for the Gaia mission, delivering on the long standing promise to provide parallaxes and proper motions for over 1 billion stars, and representing a first step in the availability of complementary radial velocity and source astrophysical information for a sample of stars in the Gaia survey which covers a very substantial fraction of the volume of our galaxy. </p> </div> <br> <dl class="s-abstract-dl-horizontal"> <dt>Publication:</dt> <dd> <div id="article-publication">Astronomy and Astrophysics</div> </dd> <dt>Pub Date:</dt> <dd>August 2018</dd> <dt>DOI:</dt> <dd> <span> <a href="/link_gateway/2018A&A...616A...1G/doi:10.1051/0004-6361/201833051" target="_blank" rel="noopener">10.1051/0004-6361/201833051</a> <i class="fa fa-external-link"></i> </span> </dd> <dt>arXiv:</dt> <dd> <span> <a href="/link_gateway/2018A&A...616A...1G/arXiv:1804.09365" target="_blank" rel="noopener">arXiv:1804.09365</a> <i class="fa fa-external-link"></i> </span> </dd> <dt>Bibcode:</dt> <dd> <a href="/abs/2018A%26A...616A...1G/abstract"> 2018A&A...616A...1G </a> <i class="icon-help" title="The bibcode is assigned by the ADS as a unique identifier for the paper."></i> </dd> <dt>Keywords:</dt> <dd> <ul class="list-inline"> <li>catalogs;</li> <li>astrometry;</li> <li>techniques: radial velocities;</li> <li>stars: fundamental parameters;</li> <li>stars: variables: general;</li> <li>minor planets;</li> <li>asteroids: general;</li> <li>Astrophysics - Astrophysics of Galaxies;</li> <li>Astrophysics - Instrumentation and Methods for Astrophysics</li> </ul> </dd> <dt>E-Print:</dt> <dd> Accepted for A&amp </dd> </dl> </article> </div> <div data-widget="ShowCitations"></div> <div data-widget="ShowReferences"></div> <div data-widget="ShowCoreads"></div> <div data-widget="ShowSimilar"></div> <div data-widget="ShowTableofcontents"></div> <div data-widget="ShowGraphics"></div> <div data-widget="ShowExportcitation" data-origin="abstract"></div> <div data-widget="ShowMetrics" data-allow-redirect="false"></div> <div data-widget="MetaTagsWidget"></div> </div> </div> </div> <div class="s-right-col-container col-xs-12 col-sm-12 col-md-3 col-lg-2 s-right-column" id="right-col-container" > <div data-widget="ShowResources"> <div data-reactroot="" class="s-right-col-widget-container" style="padding: 10px" > <div> <div class="resources__container"> <div class="resources__full__list"> <div class="resources__header__row"> <i class="fa fa-file-text-o" aria-hidden="true"> </i> <div class="resources__header__title">full text sources</div> </div> <div class="resources__content"> <div class="resources__content__title">Publisher</div> <div class="resources__content__links"> <span> <a href="/link_gateway/2018A&A...616A...1G/PUB_PDF" rel="noopener" class="resources__content__link unlock" > <i class="fa fa-file-pdf-o" aria-hidden="true"> </i> </a> <div class="resources__content__link__separator">|</div> </span> <span> <a href="/link_gateway/2018A&A...616A...1G/PUB_HTML" rel="noopener" class="resources__content__link unlock" > <i class="fa fa-file-text" aria-hidden="true"> </i> </a> </span> </div> </div> <div class="resources__content"> <div class="resources__content__title">arXiv</div> <div class="resources__content__links"> <span> <a href="/link_gateway/2018A&A...616A...1G/EPRINT_PDF" rel="noopener" class="resources__content__link unlock" > <i class="fa fa-file-pdf-o" aria-hidden="true"> </i> </a> <div class="resources__content__link__separator">|</div> </span> <span> <a href="/link_gateway/2018A&A...616A...1G/EPRINT_HTML" rel="noopener" class="resources__content__link unlock" > <i class="fa fa-file-text" aria-hidden="true"> </i> </a> </span> </div> </div> </div> <div class="resources__data__list"> <div class="resources__header__row"> <i class="fa fa-database"></i> <div class="resources__header__title">data products</div> </div> <div class="resources__content"> <a href="/link_gateway/2018A&A...616A...1G/ESO" rel="noopener" class="resources__content__link" >ESO (10)</a > <a href="/link_gateway/2018A&A...616A...1G/SIMBAD" rel="noopener" class="resources__content__link" >SIMBAD (5)</a > <a href="/link_gateway/2018A&A...616A...1G/IRSA" rel="noopener" class="resources__content__link" >IRSA (2)</a > <a href="/link_gateway/2018A&A...616A...1G/Author" rel="noopener" class="resources__content__link" >Author (1)</a > </div> </div> </div> <div data-widget="ShowAssociated"> <div data-reactroot="" class="resources__container"> <div class="resources__header__row"> <i class="fa fa-folder-open"></i> <div class="resources__header__title"> Related Materials (1) </div> </div> <div> <div style=" font-size: 1em; 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b.innerHTML += autoValues[i].match.substr(val.length); } // Insert a input field that will hold the current array item's value: b.innerHTML += "<input type='hidden' value='" + autoValues[i].value + "'>"; // Listen to clicks on the item value (DIV element): b.addEventListener("click", function(e) { var terms = searchBox.value.split(/\s+/); // Remove the current part of the input used for matching terms.pop(); // Insert the value for the autocomplete text field: terms.push(this.getElementsByTagName("input")[0].value); searchBox.value = terms.join(" "); // Move cursor position inside quotes/parenthesis if needed searchBox.focus(); if (searchBox.value[searchBox.value.length-1] === '"' || searchBox.value[searchBox.value.length-1] === ')') { searchBox.setSelectionRange(searchBox.value.length-1, searchBox.value.length-1); } // Close the list of autocompleted values closeAllLists(); }); a.appendChild(b); } } if (a.children.length > 0) { // By default, enter will select the first entry currentFocus = 0; addActive(a.children); } }); /*execute a function presses a key on the keyboard:*/ searchBox.addEventListener("keydown", function(e) { var x = document.getElementById(this.id + "autocomplete-list"); if (x) x = x.getElementsByTagName("div"); if (e.keyCode == 40) { // If the arrow DOWN key is pressed, increase the currentFocus variable: currentFocus++; addActive(x); } else if (e.keyCode == 38) { //up // If the arrow UP key is pressed, decrease the currentFocus variable: currentFocus--; /*and and make the current item more visible:*/ addActive(x); } else if (e.keyCode == 13) { // If the ENTER key is pressed: if (currentFocus > -1) { // Prevent the form from being submitted: e.preventDefault(); // Simulate a click on the "active" item: if (x) x[currentFocus].click(); currentFocus = -1; } } }); function addActive(x) { // Classify an item as "active": if (!x) return false; // Remove the "active" class on all items: removeActive(x); if (currentFocus >= x.length) currentFocus = 0; if (currentFocus < 0) currentFocus = (x.length - 1); // Add class "autocomplete-active": x[currentFocus].classList.add("autocomplete-active"); } function removeActive(x) { // Remove the "active" class from all autocomplete items: for (var i = 0; i < x.length; i++) { x[i].classList.remove("autocomplete-active"); } } function closeAllLists(elmnt) { // Close all autocomplete lists in the document, except the one passed as an argument: var x = document.getElementsByClassName("autocomplete-items"); for (var i = 0; i < x.length; i++) { if (elmnt != x[i] && elmnt != searchBox) { x[i].parentNode.removeChild(x[i]); } } } // Any other clicks in the document: document.addEventListener("click", function (e) { closeAllLists(e.target); }); } var autoList = [ { value: 'author:""', label: 'Author', match: 'author:"' }, { value: 'author:"^"', label: 'First Author', match: 'first author' }, { value: 'author:"^"', label: 'First Author', match: 'author:"^' }, { value: 'bibcode:""', label: 'Bibcode', desc: 'e.g. bibcode:1989ApJ...342L..71R', match: 'bibcode:"' }, { value: 'bibstem:""', label: 'Publication', desc: 'e.g. bibstem:ApJ', match: 'bibstem:"' }, { value: 'bibstem:""', label: 'Publication', desc: 'e.g. bibstem:ApJ', match: 'publication (bibstem)' }, { value: 'arXiv:', label: 'arXiv ID', match: 'arxiv:' }, { value: 'doi:', label: 'DOI', match: 'doi:' }, { value: 'full:""', label: 'Full text search', desc: 'title, abstract, and body', match: 'full:' }, { value: 'full:""', label: 'Full text search', desc: 'title, abstract, and body', match: 'fulltext' }, { value: 'full:""', label: 'Full text search', desc: 'title, abstract, and body', match: 'text' }, { value: 'year:', label: 'Year', match: 'year' }, { value: 'year:1999-2005', label: 'Year Range', desc: 'e.g. 1999-2005', match: 'year range' }, { value: 'aff:""', label: 'Affiliation', match: 'aff:' }, { value: 'abs:""', label: 'Search abstract + title + keywords', match: 'abs:' }, { value: 'database:astronomy', label: 'Limit to papers in the astronomy database', match: 'database:astronomy' }, { value: 'database:physics', label: 'Limit to papers in the physics database', match: 'database:physics' }, { value: 'title:""', label: 'Title', match: 'title:"' }, { value: 'orcid:', label: 'ORCiD identifier', match: 'orcid:' }, { value: 'object:', label: 'SIMBAD object (e.g. object:LMC)', match: 'object:' }, { value: 'property:refereed', label: 'Limit to refereed', desc: '(property:refereed)', match: 'refereed' }, { value: 'property:refereed', label: 'Limit to refereed', desc: '(property:refereed)', match: 'property:refereed' }, { value: 'property:notrefereed', label: 'Limit to non-refereed', desc: '(property:notrefereed)', match: 'property:notrefereed' }, { value: 'property:notrefereed', label: 'Limit to non-refereed', desc: '(property:notrefereed)', match: 'notrefereed' }, { value: 'property:eprint', label: 'Limit to eprints', desc: '(property:eprint)', match: 'eprint' }, { value: 'property:eprint', label: 'Limit to eprints', desc: '(property:eprint)', match: 'property:eprint' }, { value: 'property:openaccess', label: 'Limit to open access', desc: '(property:openaccess)', match: 'property:openaccess' }, { value: 'property:openaccess', label: 'Limit to open access', desc: '(property:openaccess)', match: 'openaccess' }, { value: 'doctype:software', label: 'Limit to software', desc: '(doctype:software)', match: 'software' }, { value: 'doctype:software', label: 'Limit to software', desc: '(doctype:software)', match: 'doctype:software' }, { value: 'property:inproceedings', label: 'Limit to papers in conference proceedings', desc: '(property:inproceedings)', match: 'proceedings' }, { value: 'property:inproceedings', label: 'Limit to papers in conference proceedings', desc: '(property:inproceedings)', match: 'property:inproceedings' }, { value: 'citations()', label: 'Citations', desc: 'Get papers citing your search result set', match: 'citations(' }, { value: 'references()', label: 'References', desc: 'Get papers referenced by your search result set', match: 'references(' }, { value: 'trending()', label: 'Trending', desc: 'Get papers most read by users who recently read your search result set', match: 'trending(' }, { value: 'reviews()', label: 'Review Articles', desc: 'Get most relevant papers that cite your search result set', match: 'reviews(' }, { value: 'useful()', label: 'Useful', desc: 'Get papers most frequently cited by your search result set', match: 'useful(' }, { value: 'similar()', label: 'Similar', desc: 'Get papers that have similar full text to your search result set', match: 'similar(' }, ]; 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