Gaia Data Release 2. Observations of solar system objects

F. Spoto (1) , P. Tanga (2) , F. Mignard (2) , J. Berthier (1) , B. Carry (1, 2) , A. Cellino (3) , A. Dell’oro , D. Hestroffer (1) , K. Muinonen (4) , T. Pauwels (5) , J. Petit , P. David , F. de Angeli (6) , M. Delbò (2) , B. Frézouls , M. Granvik , J. Guiraud , J. Hernandez , C. Ordenovic (2) , J. Portell , E. Poujoulet , W. Thuillot (1) , G. Walmsley , A. Brown , A. Vallenari , T. Prusti (7) , J. de Bruijne , C. Babusiaux (8, 9) , C. Bailer-Jones , M. Biermann , D. Evans , L. Eyer (10) , F. Jansen , C. Jordi , S. Klioner , U. Lammers , L. Lindegren , X. Luri (11) , C. Panem , D. Pourbaix (12) , S. Randich , P. Sartoretti (8) , H. Siddiqui , C. Soubiran (13) , F. van Leeuwen , A. Walton , F. Arenou (8) , U. Bastian (14) , M. Cropper , R. Drimmel , D. Katz (8) , M. Lattanzi , J. Bakker , C. Cacciari , J. Castañeda , L. Chaoul , N. Cheek , C. Fabricius , R. Guerra (15) , B. Holl , E. Masana (16) , R. Messineo , N. Mowlavi , K. Nienartowicz , P. Panuzzo (17, 8) , M. Riello , M. Seabroke , F. Thevenin (2) , G. Gracia-Abril , G. Comoretto , M. Garcia-Reinaldos , D. Teyssier , M. Altmann (18) , R. Andrae , M. Audard (19) , I. Bellas-Velidis , K. Benson , R. Blomme (5) , P. Burgess (6) , G. Busso (6) , G. Clementini (20) , M. Clotet , O. Creevey (21) , M. David , J. de Ridder (17) , L. Delchambre , C. Ducourant , J. Fernández-Hernández , M. Fouesneau , Y. Frémat (5) , M. García-Torres , J. González-Núñez , J. González-Vidal , E. Gosset (22) , P. Guy , J. Halbwachs , C. Hambly , D. Harrison , T. Hodgkin , A. Hutton , Gérard Jasniewicz (23) , A. Jean-Antoine-Piccolo , S. Jordan , J. Korn , A. Krone-Martins (24) , C. Lanza , T. Lebzelter , W. L O¨ , M. Manteiga , M. Marrese , J. Martín-Fleitas , A. Moitinho (25) , A. Mor , J. Osinde , E. Pancino (26) , A. Recio-Blanco (2) , J. Richards , L. Rimoldini , C. Robin , M. Sarro , C. Siopis , M. Smith , A. Sozzetti , M. Süveges , J. Torra , W. van Reeven , U. Abbas , A. Abreu Aramburu , S. Accart , C. Aerts , G. Altavilla , M. Álvarez , R. Alvarez , J. Alves , R. Anderson , H. Andrei (18) , E. Anglada Varela , E. Antiche , T. Antoja , B. Arcay , T. Astraatmadja (27) , N. Bach , S. Baker , L. Balaguer-Nunez (28) , P. Balm , C. Barache (18) , C. Barata , D. Barbato , F. Barblan , S. Barklem , D. Barrado (29) , M. Barros , M. Barstow (30) , L. Bartholomé Muñoz , J. Bassilana , U. Becciani , M. Bellazzini , A. Berihuete , Stefano Bertone (18) , L. Bianchi (31) , O. Bienaymé (32) , S. Blanco-Cuaresma (33) , T. Boch , C. Boeche , A. Bombrun , R. Borrachero , D. Bossini , S. Bouquillon (18) , G. Bourda , A. Bragaglia , L. Bramante , M. Breddels , A. Bressan (34) , N. Brouillet (35) , T. Brüsemeister , E. Brugaletta , B. Bucciarelli , A. Burlacu , D. Busonero , A. Butkevich , R. Buzzi , E. Caffau (8) , R. Cancelliere , G. Cannizzaro , T. Cantat-Gaudin , R. Carballo , T. Carlucci (18) , J. Carrasco (36) , L. Casamiquela , M. Castellani (37) , A. Castro-Ginard , P. Charlot , L. Chemin , A. Chiavassa (2) , G. Cocozza , G. Costigan , S. Cowell (6) , F. Crifo (8) , M. Crosta , C. Crowley , J. Cuypers (5) , C. Dafonte , Y. Damerdji (38) , A. Dapergolas , P. de Laverny (2) , F. de Luise (39) , R. de March , R. de Souza , A. de Torres , J. Debosscher (40) , E. del Pozo , A. Delgado , H. Delgado , S. Diakite (41) , C. Diener , E. Distefano , C. Dolding , P. Drazinos , J. Duran , B. Edvardsson (42) , H. Enke , K. Eriksson (42) , P. Esquej , G. Eynard Bontemps , C. Fabre (43) , M. Fabrizio (44) , S. Faigler , J. Falcão , M. Farràs Casas , L. Federici (45) , G. Fedorets , P. Fernique (46) , F. Figueras (47) , F. Filippi (48) , K. Findeisen (8) , A. Fonti , E. Fraile , M. Fraser (49) , M. Gai (3) , S. Galleti , D. Garabato , F. García-Sedano , A. Garofalo , N. Garralda , A. Gavel , P. Gavras (8) , J. Gerssen , R. Geyer , P. Giacobbe , G. Gilmore , S. Girona , G. Giuffrida , F. Glass , M. Gomes , A. Gueguen (8) , A. Guerrier (50) , R. Gutié , R. Haigron (8) , D. Hatzidimitriou (51) , M. Hauser , M. Haywood (8) , U. Heiter (42) , A. Helmi (52) , J. Heu (8) , T. Hilger , D. Hobbs , W. Hofmann , G. Holland , H. Huckle , A. Hypki , V. Icardi , K. Janssen , G. Jevardat de Fombelle , G. Jonker , L. Juhasz (53) , F. Julbe , A. Karampelas , A. Kewley , J. Klar , A. Kochoska , R. Kohley (54) , K. Kolenberg , M. Kontizas , E. Kontizas , S. Koposov , G. Kordopatis (2) , Z. Kostrzewa-Rutkowska , P. Koubsky , S. Lambert (18) , A. Lanza , Y. Lasne (55) , J. Lavigne , Y. Le Fustec , C. Le Poncin-Lafitte (56) , Y. Lebreton (8, 57) , S. Leccia , N. Leclerc (8) , I. Lecoeur-Taibi , H. Lenhardt , F. Leroux , S. Liao (58) , E. Licata , H. Lindstrøm , T. Lister , E. Livanou , A. Lobel (5) , M. López , S. Managau , G. Mann (59) , G. Mantelet (60) , O. Marchal (8) , J. Marchant (61) , M. Marconi , S. Marinoni , G. Marschalkó , J. Marshall , M. Martino , G. Marton (62) , N. Mary , D. Massari , G. Matijevič , T. Mazeh (63) , J. Mcmillan , S. Messina , D. Michalik , R. Millar , D. Molina , R. Molinaro (64) , L. Molnar , P. Montegriffo , R. Mor , R. Morbidelli , T. Morel , D. Morris , A. Mulone , T. Muraveva , I. Musella , G. Nelemans , L. Nicastro , L. Noval , W. O’mullane , D. Ordóñez-Blanco , P. Osborne , C. Pagani , I. Pagano , F. Pailler , H. Palacin , L. Palaversa , A. Panahi , M. Pawlak , M. Piersimoni , F. Pineau , E. Plachy , G. Plum (8) , E. Poggio , A. Prša , L. Pulone , E. Racero , S. Ragaini , N. Rambaux (1) , M. Ramos-Lerate , S. Regibo , C. Reyle (65) , F. Riclet , V. Ripepi (66) , A. Riva (67) , A. Rivard , G. Rixon (6) , T. Roegiers , M. Roelens , M. Romero-Gomez (68) , N. Rowell , F. Royer (8) , L. Ruiz-Dern (50, 8) , G. Sadowski , T. Sagristà Sellés , J. Sahlmann , J. Salgado , E. Salguero , N. Sanna , T. Santana-Ros (69) , M. Sarasso , H. Savietto , M. Schultheis (2) , E. Sciacca , M. Segol , C. Segovia , D. Segransan (33) , C. Shih (8) , L. Siltala , A. Silva , R. Smart (3) , K. Smith , E. Solano (70) , F. Solitro , R. Sordo , S. Soria Nieto , J. Souchay (18) , A. Spagna , U. Stampa , A. Steele (71) , H. Steidelmüller , C. Stephenson , H. Stoev , F. Suess , J. Surdej (72) , L. Szabados (73) , E. Szegedi-Elek , D. Tapiador , F. Taris (18) , G. Tauran , M. Taylor , R. Teixeira (74) , D. Terrett , P. Teyssandier (18) , A. Titarenko , F. Torra Clotet , C. Turon (8) , A. Ulla , E. Utrilla , S. Uzzi , M. Vaillant , G. Valentini (75) , V. Valette , A. van Elteren , E. van Hemelryck , M. van Leeuwen , M. Vaschetto , A. Vecchiato (76) , J. Veljanoski , Y. Viala (8) , D. Vicente (77) , S. Vogt , C. von Essen , H. Voss , V. Votruba , S. Voutsinas , M. Weiler , O. Wertz , T. Wevers (78) , Ł. Wyrzykowski , A. Yoldas (6) , M. Žerjal , H. Ziaeepour (79) , J. Zorec (80) , S. Zschocke (81) , S. Zucker (82) , C. Zurbach (23) , T. Zwitter

1 IMCCE - Institut de Mécanique Céleste et de Calcul des Ephémérides
2 LAGRANGE - Joseph Louis LAGRANGE
3 OATo - INAF - Osservatorio Astrofisico di Torino
4 HIP - Helsinki Institute of Physics
5 ROB - Royal Observatory of Belgium = Observatoire Royal de Belgique
6 Institute of Astronomy [Cambridge]
7 ESA - Agence Spatiale Européenne = European Space Agency
8 GEPI - Galaxies, Etoiles, Physique, Instrumentation
9 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
10 Geneva Observatory
11 Institut de Ciènces del Cosmos (ICC)
12 ULB - Université libre de Bruxelles
13 LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac]
14 Zentrum für astronomie
15 ULPGC - University of Las Palmas de Gran Canaria
16 Departament de Geodinamica i Geofısica, Facultat de Geologia,
17 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
18 SYRTE - Systèmes de Référence Temps Espace
19 UNIGE - Université de Genève = University of Geneva
20 UNIBO - Alma Mater Studiorum Università di Bologna = University of Bologna
21 IAS - Institut d'astrophysique spatiale
22 UPJV - Université de Picardie Jules Verne
23 LUPM - Laboratoire Univers et Particules de Montpellier
24 OASU - Observatoire aquitain des sciences de l'univers
25 FCUL - SIM/IDL Faculdade de Ciências da Universidade de Lisboa
26 OABO - INAF - Osservatorio Astronomico di Bologna
27 NIKHEF - National Institute for Subatomic Physics [Amsterdam]
28 UB - Universitat de Barcelona
29 Departamento de Astrofisica [Madrid]
30 Department of Physics and Astronomy [Leicester]
31 IPNO - Institut de Physique Nucléaire d'Orsay
32 ObAS - Observatoire astronomique de Strasbourg
33 ObsGE - Observatoire Astronomique de l'Université de Genève
34 OAPD - INAF - Osservatorio Astronomico di Padova
35 FORMATION STELLAIRE 2018
36 CICEnergigune
37 Atotech Deutschland GmbH
38 CESR - Centre d'étude spatiale des rayonnements
39 OAR - INAF - Osservatorio Astronomico di Roma
40 Institute of Astronomy [Leuven]
41 UTINAM - Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213)
42 Uppsala University
43 LSH-ENS - Laboratoire de Spectroscopie Hertzienne de l'ENS
44 SISSA / ISAS - Scuola Internazionale Superiore di Studi Avanzati / International School for Advanced Studies
45 Service de médecine interne diabète et maladies métaboliqe
46 OAS - Observatoire astronomique de Strasbourg
47 IRCELYON - Institut de recherches sur la catalyse et l'environnement de Lyon
48 UNIROMA - Università degli Studi di Roma "La Sapienza" = Sapienza University [Rome]
49 Aberystwyth University
50 CNES - Centre National d'Études Spatiales [Toulouse]
51 Department of Physics [Athens]
52 Departament Llenguatges i Sistemes Informatics,
53 DEE
54 ESAC - European Space Astronomy Centre
55 L3AB - Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux
56 LNE - SYRTE - Laboratoire national de métrologie et d'essais - Systèmes de Référence Temps-Espace
57 IPR - Institut de Physique de Rennes
58 CAS - Chinese Academy of Sciences [Beijing]
59 AIP - Leibniz-Institut für Astrophysik Potsdam
60 ATMEL - Atmel Corporation
61 ARI - Astrophysics Research Institute [Liverpool]
62 TKK - TKK Helsinki University of Technology
63 TAU - School of Physics and Astronomy [Tel Aviv]
64 Istituto Nazionale di Astrofisica - Istituto Nazionale di Astrofisica
65 LAOB - Laboratoire d'astrophysique de l'observatoire de Besançon (UMR 6091)
66 OAC - INAF - Osservatorio Astronomico di Capodimonte
67 IREBS - Institut de recherche de l'European Business School
68 LAM - Laboratoire d'Astrophysique de Marseille
69 Astronomical Observatory [Poznan]
70 SVO - Spanish Virtual Observatory - Observatorio Virtual Español
71 Geophysical Laboratory [Carnegie Institution]
72 Institut d'Astrophysique et de Géophysique [Liège]
73 Konkoly Observatory
74 IAG - Instituto de Astronomia, Geofísica e Ciências Atmosféricas [São Paulo]
75 Dipartimento di Fisica
76 Astrometry
77 Karl-Franzens-Universität Graz
78 Department of Astrophysics [Nijmegen]
79 LAL - Laboratoire de l'Accélérateur Linéaire
80 IAP - Institut d'Astrophysique de Paris
81 Lohrmann Observatory
82 BGU - Ben-Gurion University of the Negev

Context. The Gaia spacecraft of the European Space Agency (ESA) has been securing observations of solar system objects (SSOs) since the beginning of its operations. Data Release 2 (DR2) contains the observations of a selected sample of 14,099 SSOs. These asteroids have been already identified and have been numbered by the Minor Planet Center repository. Positions are provided for each Gaia observation at CCD level. As additional information, complementary to astrometry, the apparent brightness of SSOs in the unfil-tered G band is also provided for selected observations. Aims. We explain the processing of SSO data, and describe the criteria we used to select the sample published in Gaia DR2. We then explore the data set to assess its quality. Methods. To exploit the main data product for the solar system in Gaia DR2, which is the epoch astrometry of asteroids, it is necessary to take into account the unusual properties of the uncertainty, as the position information is nearly one-dimensional. When this aspect is handled appropriately, an orbit fit can be obtained with post-fit residuals that are overall consistent with the a-priori error model that was used to define individual values of the astrometric uncertainty. The role of both random and systematic errors is described. The distribution of residuals allowed us to identify possible contaminants in the data set (such as stars). Photometry in the G band was compared to computed values from reference asteroid shapes and to the flux registered at the corresponding epochs by the red and blue photometers (RP and BP). Results. The overall astrometric performance is close to the expectations, with an optimal range of brightness G ∼ 12 − 17. In this range, the typical transit-level accuracy is well below 1 mas. For fainter asteroids, the growing photon noise deteriorates the performance. Asteroids brighter than G ∼ 12 are affected by a lower performance of the processing of their signals. The dramatic improvement brought by Gaia DR2 astrometry of SSOs is demonstrated by comparisons to the archive data and by preliminary tests on the detection of subtle non-gravitational effects.

Domaines: Instrumentation et méthodes pour l'astrophysique [astro-ph.IM]; Astrophysique [astro-ph]

F. Spoto, P. Tanga, F. Mignard, J. Berthier, B. Carry, et al.. Gaia Data Release 2. Observations of solar system objects. Astronomy and Astrophysics - A&A, 2018, 616, pp.id.A13. ⟨10.1051/0004-6361/201832900⟩. ⟨hal-01867330⟩