@article{3070204,
    title = "The Gaia astrophysical parameters inference system (Apsis): Pre-launch description",
    author = "Bailer-Jones, C.A.L. and Andrae, R. and Arcay, B. and Astraatmadja, T. and Bellas-Velidis, I. and Berihuete, A. and Bijaoui, A. and Carrión, C. and Dafonte, C. and Damerdji, Y. and Dapergolas, A. and De Laverny, P. and Delchambre, L. and Drazinos, P. and Drimmel, R. and Frémat, Y. and Fustes, D. and García-Torres, M. and Guédé, C. and Heiter, U. and Janotto, A.-M. and Karampelas, A. and Kim, D.-W. and Knude, J. and Kolka, I. and Kontizas, E. and Kontizas, M. and Korn, A.J. and Lanzafame, A.C. and Lebreton, Y. and Lindstrøm, H. and Liu, C. and Livanou, E. and Lobel, A. and Manteiga, M. and Martayan, C. and Ordenovic, C. and Pichon, B. and Recio-Blanco, A. and Rocca-Volmerange, B. and Sarro, L.M. and Smith, K. and Sordo, R. and Soubiran, C. and Surdej, J. and Thévenin, F. and Tsalmantza, P. and Vallenari, A. and Zorec, J.",
    journal = "Chinese Astronomy and Astrophysics",
    year = "2013",
    volume = "559",
    issn = "0275-1062",
    doi = "10.1051/0004-6361/201322344",
    keywords = "Astrophysical parameters;  Effective temperature;  Formation and evolutions;  Galaxies: fundamental parameters;  Interstellar extinction;  Methods:data analysis;  Methods:statistical;  Stars:fundamental parameters;  Astrophysical parameters;  Effective temperature;  Formation and evolutions;  Galaxies: fundamental parameters;  Interstellar extinction;  Methods:data analysis;  Methods:statistical;  Stars:fundamental parameters, Astrophysics;  Galaxies;  Geometrical optics;  Stars;  Surveying;  Surveys;  Astrophysics;  Data handling;  Galaxies;  Geometrical optics;  Information analysis;  Stars;  Surveying;  Surveys;  Thermal logging, Satellites;  Satellites",
    abstract = "The Gaia satellite will survey the entire celestial sphere down to 20th magnitude, obtaining astrometry, photometry, and low resolution spectrophotometry on one billion astronomical sources, plus radial velocities for over one hundred million stars. Itsmain objective is to take a census of the stellar content of our Galaxy, with the goal of revealing its formation and evolution. Gaia's unique feature is the measurement of parallaxes and proper motions with hitherto unparalleled accuracy for many objects. As a survey, the physical properties of most of these objects are unknown. Here we 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. This system covers single stars, (unresolved) binary stars, quasars, and galaxies, all covering a wide parameter space. Multiple methods are used for many types of stars, producing multiple results for the end user according to different models and assumptions. Prior to its application to real Gaia data the accuracy of these methods cannot be assessed definitively. But as an example of the current performance, we can attain internal accuracies (rms residuals) on F, G, K, M dwarfs and giants at G = 15 (V = 15-17) for a wide range of metallicites and interstellar extinctions of around 100 K in effective temperature (Teff), 0.1 mag in extinction (A0), 0.2 dex in metallicity ([Fe/H]), and 0.25 dex in surface gravity (log g). The accuracy is a strong function of the parameters themselves, varying by a factor of more than two up or down over this parameter range. After its launch in December 2013, Gaia will nominally observe for five years, during which the system we describe will continue to evolve in light of experience with the real data. © ESO, 2013."
}