Gaia Data Release 2 The celestial reference frame (Gaia-CRF2)

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Gaia Data Release 2 The celestial reference frame (Gaia-CRF2). / Gaia Collaboration.

In: Astronomy & Astrophysics, Vol. 616, 14, 10.08.2018.

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Gaia Collaboration. / Gaia Data Release 2 The celestial reference frame (Gaia-CRF2). In: Astronomy & Astrophysics. 2018 ; Vol. 616.

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@article{938fd94dd9964a4e8d139af7689f075d,
title = "Gaia Data Release 2 The celestial reference frame (Gaia-CRF2)",
abstract = "Context. The second release of Gaia data (Gaia DR2) contains the astrometric parameters for more than half a million quasars. This set defines a kinematically non-rotating reference frame in the optical domain. A subset of these quasars have accurate VLBI positions that allow the axes of the reference frame to be aligned with the International Celestial Reference System (ICRF) radio frame. Aims. We describe the astrometric and photometric properties of the quasars that were selected to represent the celestial reference frame of Gaia DR2 (Gaia-CRF2), and to compare the optical and radio positions for sources with accurate VLBI positions.Methods. Descriptive statistics are used to characterise the overall properties of the quasar sample. Residual rotation and orientation errors and large-scale systematics are quantified by means of expansions in vector spherical harmonics. Positional differences are calculated relative to a prototype version of the forthcoming ICRF3.Results. Gaia-CRF2 consists of the positions of a sample of 556 869 sources in Gaia DR2, obtained from a positional cross-match with the ICRF3-prototype and AllWISE AGN catalogues. The sample constitutes a clean, dense, and homogeneous set of extragalactic point sources in the magnitude range G similar or equal to 16 to 21 mag with accurately known optical positions. The median positional uncertainty is 0.12 mas for G <18 mag and 0.5 mas at G = 20 mag. Large-scale systematics are estimated to be in the range 20 to 30 mu as. The accuracy claims are supported by the parallaxes and proper motions of the quasars in Gaia DR2. The optical positions for a subset of 2820 sources in common with the ICRF3-prototype show very good overall agreement with the radio positions, but several tens of sources have significantly discrepant positions.Conclusions. Based on less than 40{\%} of the data expected from the nominal Gaia mission, Gaia-CRF2 is the first realisation of a non-rotating global optical reference frame that meets the ICRS prescriptions, meaning that it is built only on extragalactic sources. Its accuracy matches the current radio frame of the ICRF, but the density of sources in all parts of the sky is much higher, except along the Galactic equator.",
keywords = "astrometry, reference systems, catalogs, PROPER MOTIONS, INTERFEROMETRY",
author = "F. Mignard and Klioner, {S. A.} and L. Lindegren and J. Hernandez and U. Bastian and A. Bombrun and D. Hobbs and U. Lammers and D. Michalik and M. Ramos-Lerate and M. Biermann and J. Fernandez-Hernandez and R. Geyer and T. Hilger and Siddiqui, {H. I.} and H. Steidelmueller and C. Babusiaux and C. Barache and S. Lambert and Andrei, {A. H.} and G. Bourda and P. Charlot and Brown, {A. G. A.} and A. Vallenari and T. Prusti and {de Bruijne}, {J. H. J.} and Bailer-Jones, {C. A. L.} and Evans, {D. W.} and L. Eyer and F. Jansen and C. Jordi and X. Luri and C. Panem and D. Pourbaix and S. Randich and P. Sartoretti and C. Soubiran and {van Leeuwen}, F. and Walton, {N. A.} and F. Arenou and M. Cropper and R. Drimmel and D. Katz and Lattanzi, {M. G.} and J. Bakker and C. Cacciari and J. Castaneda and L. Chaoul and D. Bossini and {von Essen}, C. and {Gaia Collaboration}",
year = "2018",
month = "8",
day = "10",
doi = "10.1051/0004-6361/201832916",
language = "English",
volume = "616",
journal = "Astronomy & Astrophysics",
issn = "0004-6361",
publisher = "E D P Sciences",

}

RIS

TY - JOUR

T1 - Gaia Data Release 2 The celestial reference frame (Gaia-CRF2)

AU - Mignard, F.

AU - Klioner, S. A.

AU - Lindegren, L.

AU - Hernandez, J.

AU - Bastian, U.

AU - Bombrun, A.

AU - Hobbs, D.

AU - Lammers, U.

AU - Michalik, D.

AU - Ramos-Lerate, M.

AU - Biermann, M.

AU - Fernandez-Hernandez, J.

AU - Geyer, R.

AU - Hilger, T.

AU - Siddiqui, H. I.

AU - Steidelmueller, H.

AU - Babusiaux, C.

AU - Barache, C.

AU - Lambert, S.

AU - Andrei, A. H.

AU - Bourda, G.

AU - Charlot, P.

AU - Brown, A. G. A.

AU - Vallenari, A.

AU - Prusti, T.

AU - de Bruijne, J. H. J.

AU - Bailer-Jones, C. A. L.

AU - Evans, D. W.

AU - Eyer, L.

AU - Jansen, F.

AU - Jordi, C.

AU - Luri, X.

AU - Panem, C.

AU - Pourbaix, D.

AU - Randich, S.

AU - Sartoretti, P.

AU - Soubiran, C.

AU - van Leeuwen, F.

AU - Walton, N. A.

AU - Arenou, F.

AU - Cropper, M.

AU - Drimmel, R.

AU - Katz, D.

AU - Lattanzi, M. G.

AU - Bakker, J.

AU - Cacciari, C.

AU - Castaneda, J.

AU - Chaoul, L.

AU - Bossini, D.

AU - von Essen, C.

AU - Gaia Collaboration

PY - 2018/8/10

Y1 - 2018/8/10

N2 - Context. The second release of Gaia data (Gaia DR2) contains the astrometric parameters for more than half a million quasars. This set defines a kinematically non-rotating reference frame in the optical domain. A subset of these quasars have accurate VLBI positions that allow the axes of the reference frame to be aligned with the International Celestial Reference System (ICRF) radio frame. Aims. We describe the astrometric and photometric properties of the quasars that were selected to represent the celestial reference frame of Gaia DR2 (Gaia-CRF2), and to compare the optical and radio positions for sources with accurate VLBI positions.Methods. Descriptive statistics are used to characterise the overall properties of the quasar sample. Residual rotation and orientation errors and large-scale systematics are quantified by means of expansions in vector spherical harmonics. Positional differences are calculated relative to a prototype version of the forthcoming ICRF3.Results. Gaia-CRF2 consists of the positions of a sample of 556 869 sources in Gaia DR2, obtained from a positional cross-match with the ICRF3-prototype and AllWISE AGN catalogues. The sample constitutes a clean, dense, and homogeneous set of extragalactic point sources in the magnitude range G similar or equal to 16 to 21 mag with accurately known optical positions. The median positional uncertainty is 0.12 mas for G <18 mag and 0.5 mas at G = 20 mag. Large-scale systematics are estimated to be in the range 20 to 30 mu as. The accuracy claims are supported by the parallaxes and proper motions of the quasars in Gaia DR2. The optical positions for a subset of 2820 sources in common with the ICRF3-prototype show very good overall agreement with the radio positions, but several tens of sources have significantly discrepant positions.Conclusions. Based on less than 40% of the data expected from the nominal Gaia mission, Gaia-CRF2 is the first realisation of a non-rotating global optical reference frame that meets the ICRS prescriptions, meaning that it is built only on extragalactic sources. Its accuracy matches the current radio frame of the ICRF, but the density of sources in all parts of the sky is much higher, except along the Galactic equator.

AB - Context. The second release of Gaia data (Gaia DR2) contains the astrometric parameters for more than half a million quasars. This set defines a kinematically non-rotating reference frame in the optical domain. A subset of these quasars have accurate VLBI positions that allow the axes of the reference frame to be aligned with the International Celestial Reference System (ICRF) radio frame. Aims. We describe the astrometric and photometric properties of the quasars that were selected to represent the celestial reference frame of Gaia DR2 (Gaia-CRF2), and to compare the optical and radio positions for sources with accurate VLBI positions.Methods. Descriptive statistics are used to characterise the overall properties of the quasar sample. Residual rotation and orientation errors and large-scale systematics are quantified by means of expansions in vector spherical harmonics. Positional differences are calculated relative to a prototype version of the forthcoming ICRF3.Results. Gaia-CRF2 consists of the positions of a sample of 556 869 sources in Gaia DR2, obtained from a positional cross-match with the ICRF3-prototype and AllWISE AGN catalogues. The sample constitutes a clean, dense, and homogeneous set of extragalactic point sources in the magnitude range G similar or equal to 16 to 21 mag with accurately known optical positions. The median positional uncertainty is 0.12 mas for G <18 mag and 0.5 mas at G = 20 mag. Large-scale systematics are estimated to be in the range 20 to 30 mu as. The accuracy claims are supported by the parallaxes and proper motions of the quasars in Gaia DR2. The optical positions for a subset of 2820 sources in common with the ICRF3-prototype show very good overall agreement with the radio positions, but several tens of sources have significantly discrepant positions.Conclusions. Based on less than 40% of the data expected from the nominal Gaia mission, Gaia-CRF2 is the first realisation of a non-rotating global optical reference frame that meets the ICRS prescriptions, meaning that it is built only on extragalactic sources. Its accuracy matches the current radio frame of the ICRF, but the density of sources in all parts of the sky is much higher, except along the Galactic equator.

KW - astrometry

KW - reference systems

KW - catalogs

KW - PROPER MOTIONS

KW - INTERFEROMETRY

U2 - 10.1051/0004-6361/201832916

DO - 10.1051/0004-6361/201832916

M3 - Journal article

VL - 616

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

M1 - 14

ER -