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dc.contributor.authorLindegren, Len
dc.contributor.authorHernandez, Jen
dc.contributor.authorBombrun, Aen
dc.contributor.authorKlioner, Sen
dc.contributor.authorBastian, Uen
dc.contributor.authorRamos-Lerate, Men
dc.contributor.authorTorres, A deen
dc.contributor.authorSteidelmuller, Hen
dc.contributor.authorStephenson, Cen
dc.contributor.authorHobbs, Den
dc.contributor.authorLammers, Uen
dc.contributor.authorBiermann, Men
dc.contributor.authorGeyer, Ren
dc.contributor.authorHilger, Ten
dc.contributor.authorMichalik, Den
dc.contributor.authorStampa, Uen
dc.contributor.authorMcMillan, PJen
dc.contributor.authorCastaneda, Jen
dc.contributor.authorClotet, Men
dc.contributor.authorComoretto, Gen
dc.contributor.authorDavidson, Men
dc.contributor.authorFabricius, Cen
dc.contributor.authorGracia, Gen
dc.contributor.authorHambly, NCen
dc.contributor.authorHutton, Aen
dc.contributor.authorMora, Aen
dc.contributor.authorPortell, Jen
dc.contributor.authorLeeuwen, F vanen
dc.contributor.authorAbbas, Uen
dc.contributor.authorAbreu, Aen
dc.contributor.authorAltmann, Men
dc.contributor.authorAndrei, Aen
dc.contributor.authorAnglada, Een
dc.contributor.authorBalaguer-Nunez, Len
dc.contributor.authorBarache, Cen
dc.contributor.authorBecciani, Uen
dc.contributor.authorBertone, Sen
dc.contributor.authorBianchi, Len
dc.contributor.authorBouquillon, Sen
dc.contributor.authorBourda, Gen
dc.contributor.authorBrusemeister, Ten
dc.contributor.authorBucciarelli, Ben
dc.contributor.authorBusonero, Den
dc.contributor.authorBuzzi, Ren
dc.contributor.authorCancelliere, Ren
dc.contributor.authorCarlucci, Ten
dc.contributor.authorCharlot, Pen
dc.contributor.authorCheek, Nen
dc.contributor.authorCrosta, Men
dc.contributor.authorCrowley, Cen
dc.contributor.authorBruijne, J deen
dc.contributor.authorFelice, F deen
dc.contributor.authorDrimmel, Ren
dc.contributor.authorEsquej, Pen
dc.contributor.authorFienga, Aen
dc.contributor.authorFraile, Een
dc.contributor.authorGai, Men
dc.contributor.authorGarralda, Nen
dc.contributor.authorGonzalez-Vidal, JJen
dc.contributor.authorGuerra, Ren
dc.contributor.authorHauser, Men
dc.contributor.authorHofmann, Wen
dc.contributor.authorHoll, Ben
dc.contributor.authorJordan, Sen
dc.contributor.authorLattanzi, MGen
dc.contributor.authorLenhardt, Hen
dc.contributor.authorLiao, Sen
dc.contributor.authorLicata, Een
dc.contributor.authorLister, Ten
dc.contributor.authorLoffler, Wen
dc.contributor.authorMarchant, Jen
dc.contributor.authorMartin-Fleitas, J-Men
dc.contributor.authorMessineo, Ren
dc.contributor.authorMignard, Fen
dc.contributor.authorMorbidelli, Ren
dc.contributor.authorPoggio, Een
dc.contributor.authorRiva, Aen
dc.contributor.authorRowell, Nen
dc.contributor.authorSalguero, Een
dc.contributor.authorSarasso, Men
dc.contributor.authorSciacca, Een
dc.contributor.authorSiddiqui, Hen
dc.contributor.authorSmart, RLen
dc.contributor.authorSpagna, Aen
dc.contributor.authorSteele, Ien
dc.contributor.authorTaris, Fen
dc.contributor.authorTorra, Jen
dc.contributor.authorElteren, A vanen
dc.contributor.authorReeven, W vanen
dc.contributor.authorVecchiato, Aen
dc.date.accessioned2018-09-10T10:35:40Z
dc.date.available2018-09-10T10:35:40Z
dc.identifier.issn0004-6361
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/279981
dc.description.abstractGaia 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. We describe the input data, models, and processing used for the astrometric content of Gaia DR2, and the validation of these results performed within the astrometry task. 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. Special validation solutions were used to characterise the random and systematic errors in parallax and proper motion. 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 mas at G=20 mag. In the proper motion components the corresponding uncertainties are 0.05, 0.2, and 1.2 mas/yr, 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. 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 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.
dc.description.sponsorshipIncludes STFC.
dc.languageengen
dc.publisherEDP Sciences
dc.subjectastrometryen
dc.subjectparallaxesen
dc.subjectproper motionsen
dc.subjectmethods: data analysisen
dc.subjectspace vehicles: instrumentsen
dc.titleGaia Data Release 2: The astrometric solutionen
dc.typeArticle
prism.numberA2en
prism.publicationNameAstronomy & Astrophysicsen
prism.volume616en
dc.identifier.doi10.17863/CAM.27346
dcterms.dateAccepted2018-03-06en
rioxxterms.versionofrecord10.1051/0004-6361/201832727en
rioxxterms.versionVoR*
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserveden
rioxxterms.licenseref.startdate2018-03-06en
dc.identifier.eissn1432-0746
rioxxterms.typeJournal Article/Reviewen
pubs.funder-project-idSTFC (ST/K000756/1)
pubs.funder-project-idSTFC (ST/L006553/1)
pubs.funder-project-idSTFC (ST/N000641/1)
cam.issuedOnline2018-08-10en
dc.identifier.urlhttps://www.aanda.org/articles/aa/abs/2018/08/aa32727-18/aa32727-18.htmlen


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