The library collates Gaia conference proceedings, selected reports, papers, and articles on the Gaia mission as well as public DPAC documents. The right-hand menu provides arXiv.org/astro-ph and ADS search links for peer-reviewed papers on scientific topics covered by Gaia. A list of Gaia acronyms, which is maintained by Jos de Bruijne, is available online.

Livelink is the document management system used for scientific documents from Gaia. Livelink is password protected: DPAC users with personal Gaia user name and password may access Livelink once they have logged on to MyPortal.

GAIA: At the Frontiers of Astrometry
Sevres, France, 7-11 June 2010
The publication is available online.

Joint Discussion 5 at the XXVII IAU General Assembly: Modelling the Milky Way in the Era of Gaia
Rio de Janeiro, Brazil, 6-7 August 2009
The publication is available online.

ESA's 'Billion-pixel' Camera
ESA Bulletin 137, February 2009
The publication is available online.

Report by the ESA-ESO Working Group on Galactic Populations, Chemistry and Dynamics
Chair: C. Turon; Co-chair: F. Primas
Published by ESA and ESO (June 2008) and available online.

Pinpointing the Milky Way - The Formidable Challenge of Processing Gaia's Data
ESA Bulletin 132, November 2007
The publication is available online.

IAU Symposium Number 248. A Giant Step: From Milli- to Micro- Arcsecond Astrometry
Shanghai, China, 15-19 October 2007
Editors: W.J. Jin, I. Platais, M.A.C. Perryman
The proceedings are published by Cambridge University Press as A Giant Step: from Milli- to Micro-arcsecond Astrometry, Proceedings of the International Astronomical Union, IAU Symposium, Volume 248, 2008.

The Three-Dimensional Universe with Gaia
Observatoire de Paris-Meudon, France, 4-7 October 2004
Editors: C. Turon, K.S. O'Flaherty, M.A.C. Perryman
The proceedings are published by ESA as The Three-Dimensional Universe with Gaia, ESA SP-576 (January 2005). Original copies may be ordered from the ESA publications division.

Gaia Spectroscopy, Science and Technology
Gressony Saint Jean, Valle d'Aosta, Italy, 9-12 September 2002
Editor: U. Munari
The proceedings are published in the Conference Series of the Astronomical Society of the Pacific as Gaia Spectroscopy, Science and Technology, ASP Conference Series, Volume 298 (2003).

Census of the Galaxy: Challenges for Photometry and Spectrometry with Gaia
Vilnius, Lithuania, 2-6 July 2001
Editors: V. Vansevicius, A. Kucinskas, J. Sudzius
The proceedings are published in Astrophysics and Space Science, Volume 280, Issue 1-2 (2002).

Gaia: a European Space Project
Les Houches Summer School, France, 14-18 May 2001
Editors: O. Bienaymé and C. Turon
The proceedings are published in the European Astronomical Society Publications Series as Gaia: a European Space Project, EAS Publications Series, Volume 2 (2002).

Gaia: Composition, Formation and Evolution of the Galaxy
This document is the Gaia Concept and Technology Study Report (CTSR), limited to the scientific case on which the mission was accepted within ESA's scientific programme. For the record, the full Gaia Concept and Technology Study Report (ESA-SCI(2000)4), published in July 2000, as well as ESA's glossy Gaia brochure (ESA BR-163), published in August 2000, are available too. An associated summary paper has been published in Astronomy & Astrophysics, Volume 369, 339-363 (2001) and in the ESA Bulletin 103 (August 2000). Note that the technical design details in these documents have been superseded, although the essential design objectives remain unaffected.

Future Possibilities for Astrometry in Space
A joint RGO-ESA workshop, Cambridge, United Kingdom, 19-21 June 1995
Editors: M.A.C. Perryman and F. van Leeuwen
The proceedings are published by ESA as Future Possibilities for Astrometry in Space, ESA SP-379 (September 1995).

Combining probabilities
Author: C.A.L. Bailer-Jones, K. Smith
Document code: GAIA-C8-TN-MPIA-CBJ-053
Summary: We show how to combine posterior probabilities from an emsemble of models, each of which estimates the same parameter (or class) but using "independent" data. From this we describe how to separate out and replace the class prior (or the model-based prior) of a classifier post hoc and show how this relates to the combination problem...
The publication is available online.
Bibtex entry for this abstract

The maximum reachable astrometric precision: The Cramer-Rao limit
Author: U. Bastian
Document code: 2004BASNOCODE
Summary: This small investigation shall give a concise insight into the theory of astrometric measuring precision.
The publication is available online.
Bibtex entry for this abstract

Description of the Ring Solution
Author: H. Bernstein, S. Hirte, U. Bastian
Document code: GAIA-ARI-BST-001
Summary: The task First Look Preprocessing (FLP) provides a daily check of the functioning of Gaia on the basis of the scientic measurements of the satellite. Within this task, the Ring Solution is a special algorithm with some resemblances to the Great-Circle Reduction of ESA's astrometry satellite HIPPARCOS. The observed stars are connected by their astrometric, attitude and calibration parameters so they form a ring on the celestial sphere. Here, the special interest of the Ring Solution is the estimability and the accuracy of an appropriate set of parameters describing all quantities in question.
The publication is available online.
Bibtex entry for this abstract

Helmert blocking algebra in ODAS
Author: A. Bombrun
Document code: GAIA-C3-TN-ARI-APB-002
Summary: This technical note describes the mathematical process used to solve a least square problem in space astrometry that presents an Helmert blocking structure. We focus particularly on its implementation in ODAS. We assume that the reader is familiar with the space astrometric least square problem.
The publication is available online.
Bibtex entry for this abstract

Sparseness structure of the Gaia least-square problem and the (non-)feasibility of a direct method
Author: A. Bombrun
Document code: GAIA-C3-TN-ARI-APB-001
Summary: In order to build the Gaia celestial map with an accuracy of micro-arcseconds it has been demonstrated that we have to recover the attitude of the spacecraft and calibrate the instruments with the same accuracy. Gaia will be calibrated by adjusting all the parameters to fit all the measurements as good as possible. From a mathematical point of view, this problem has been formulated as a least-square system. In this note we investigate its sparseness structure.
The publication is available online.
Bibtex entry for this abstract

Astrometric planet detectability with Gaia, a short AGISLab study
Authors: B. Holl
Document code: GAIA-C3-TN-LU-BH-003
Summary: This note describes the results of a planet-course project in which the Gaia detectability of a planet in circular orbit around a solar-like star was studies with AGISLab. Besides a short theoretical background we describe how we modelled and simulated our data.
The publication is available online.
Bibtex entry for this abstract

ODAS: process description and collection of relevant mathematical algorithms
Authors: S. Jordan, U. Bastian, W. Löffler
Document code: GAIA-C3-TN-ARI-SJ-009
Summary: The aim of this document is to provide a detailed description of the ODAS processes and the underlying algorithms.
The publication is available online.
Bibtex entry for this abstract

A general Maximum-Likelihood algorithm for model fitting to CCD sample data
Author: L. Lindegren
Document code: GAIA-C3-TN-LU-LL-078
Summary: A general Maximum-Likelihood algorithm is described for fitting arbitrary models to CCD samples, where data are modelled as a Poisson process plus (gaussian) readout noise. It can be applied for example to 1D (LSF) and 2D (PSF) centroiding, but also for estimating the parameters of the LSF, PSF or CDM models.
The publication is available online.
Bibtex entry for this abstract

A theoretical investigation of chromaticity
Author: L. Lindegren
Document code: GAIA-CA-TN-LU-LL-064
Summary: Some general results are derived on the chromatic properties of diffraction images for arbitrary wavefront errors. Although the theoretical results are probably of limited practical use, they are nevertheless important for understanding the behaviour of actual centroiding algorithms in real optical systems...
The publication is available online.
Bibtex entry for this abstract

Attitude parameterization for Gaia
Author: L. Lindegren
Document code: SAG-LL-030
Summary: The Gaia attitude may be described by four continuous functions of time q₁(t), q₂(t), q₃(t), q₄(t), which form a quaternion of approximately unit length. The quaternion formalism is elegant and computationally efficient, reducing the use of trigonometric functions to a minimum. As examples of the use of quaternions, I discuss the nominal scannig law, the inertial rotation of the instrument, and the determination of the instantaneous attitude from direction measurements.
The publication is available online.
Bibtex entry for this abstract

Centroid definition for the Astro Line Spread Function
Author: L. Lindegren
Document code: GAIA-C3-TN-LU-LL-068
Summary: Issues related to the geometric and photometric calibration of the Astro Line Spread Function (LSF) are briefly discussed, in particular the separation of shape, position and flux, and the precise definition of the centroid. A convention for the centroid definition is proposed, based on a simple analytical weighting function, which appears close to optimal (for Gaia-3 parameters and typical WFE) from the viewpoint of statistical precision and interpolation accuracy. It is furthermore proposed that this weighting function is used for the very initial centroiding on AF samples, before the LSF has been calibrated.
The publication is available online.
Bibtex entry for this abstract

Charge trapping effects in CCDs for Gaia astrometry
Author: L. Lindegren
Document code: SAG-LL-022
Summary: It is known that the photon flux and the density of stars on the sky are in principle more than sufficient to calibrate the geometry of the CCDs to the required accuracy in Gaia, even considering that each pixel column must be separately calibrated. However, this assumes that the mean centroid shift can be calibrated, which becomes in practice impossible...
The publication is available online.
Bibtex entry for this abstract

Mathematical framework for the AGIS system orientation
Author: L. Lindegren
Document code: GAIA-C3-TN-LU-LL-072
Summary: This note describes the mathematical framework for determining and correcting the system orientation of the source and attitude data resulting from the Astrometric Global Iterative Solution (AGIS).
The publication is available online.
Bibtex entry for this abstract

Minimum-dimension LSF modelling
Author: L. Lindegren
Document code: GAIA-C3-TN-LU-LL-084
Summary: For the LSF and PSF calibration in the Gaia IDT/IDU we need LSF/PSF models that are both accurate and have as few free parameters as possible. General-purpose functions such as splines are not the best choice since they tend to require more parameters than strictly necessary, and have a tendency to become unstable when fitted to noisy or inhomogeneous data. Using Principal Component Analysis (PCA)...
The publication is available online.
Bibtex entry for this abstract

Normal places in least-squares problems, and their relation to the ring solution and ring-to-sphere solution
Author: L. Lindegren
Document code: GAIA-C3-TN-LU-LL-076
Summary: This note is an attempt to define precisely the meaning of 'Normal Place' in the context of linear least-squares problems. Under certain conditions, it is found that the use of normal places allows an exact decomposition of the problem. Its relation to the Ring Solution and the Ring-to-Sphere Solution is briefly discussed.
The publication is available online.
Bibtex entry for this abstract

Representation of LSF and PSF for GDAAS-2
Author: L. Lindegren
Document code: GAIA-LL-046
Summary: A parametrisation of the quasi-monochromatic line-spread function (LSF) for GAIA is proposed, using an analytical function describing the diffraction wings plus a 'bi-quartic' spline representation of the core. The quasi-monochromatic point-spread function (PSF) is modelled as the product of the along-scan and across-scan LSFs. Two appendices give details on the numerical PSF calculation and on bi-quartic B-splines.
The publication is available online.
Bibtex entry for this abstract

Scientific requirements for basic angle stability and monitoring
Author: L. Lindegren
Document code: GAIA-LL-057
Summary: The scientific requirements for the basic angle stability and the monitoring of basic angle variations are reviewed in light of the need for absolute parallax determination, which is a primary goal of Gaia. Requirements are proposed for the random and systematic basic angle variations, and for the measurement of these variations.
The publication is available online.
Bibtex entry for this abstract

Using the Conjugate Gradient method in AGIS
Author: L. Lindegren
Document code: GAIA-C3-TN-LU-LL-077
Summary: This note describes how the Conjugate Gradient method could be implemented in the AGIS framework for improved speed and accuracy.
The publication is available online.
Bibtex entry for this abstract

The performance of GSP-Phot with SVM and ILIUM
Author: C. Liu, C.A.L. Bailer-Jones
Document code: GAIA-C8-TN-MPIA-CHL-005
Summary: GSP-Phot will estimate stellar astrophysical parameters for all stellar objects with Gaia BP/RP spectra. Several algorithms will be applied in GSP-Phot in order to deal with all kind of objects in a better way...
The publication is available online.
Bibtex entry for this abstract

DPAC Proposal for the Gaia Data Processing
Authors: F. Mignard, R. Drimmel
Document code: GAIA-CD-SP-DPAC-FM-030
Summary: This document is the proposal of the Data Processing and Analysis Consortium (DPAC) issued in response to the ESA Announcement of Opportunity for the Gaia Data Processing. The document describes the key elements of the data processing and explains how the DPAC will face the challenge posed by Gaia's data processing requirements. It includes descriptions of the principles and methods to be employed in the processing and explains how DPAC will develop, test and implement the processing.
The publication is available online.
Bibtex entry for this abstract

Large Scientific Data Systems: analysis of some existing projects and their applicability to Gaia
Author: W. O'Mullane
Document code: GAIA-C1-TN-ESAC-WOM-003
Summary: This study concerns existing astronomical systems and their relevance to the Gaia mission.
The publication is available online.
Bibtex entry for this abstract

Ground Based Observations of Gaia: First tests using WMAP
Author: R.L. Smart, A. Andrei, S. Bouquillon, F. Taris
Document code: GAIA-C3-TN-OATO-RLS-002
Summary: We discuss the first tests carried out with a goal of defining the procedures for the Ground Based Optical Tracking (GBOT) of Gaia. We have made observations of the Wilkinson Microwave Anisotropy Probe in both guiding-on-the-stars and guiding-on-the-satellite modes. We present the results of these tests and, considerations of the required detector size and proposed filter choice.
The publication is available online.
Bibtex entry for this abstract

The Initial Gaia Source List 1.0: Production and Plans
Author: R.L. Smart, R. Morbidelli, L. Nicastro, R. Pannunzio, A. Spagna
Document code: GAIA-C3-TN-OATO-RLS-001
Summary: We discuss the production of the first version of the Initial Gaia Source List (IGSL). This is only an approximate version of what will be the final product but it is still useful now as it is of the expected size and content so can be used to develop routines for the Gaia reduction pipeline, as a reference point for auxiliary catalogs and for simulations. We explore the probable role of the IGSL in the Gaia data reduction and other possible uses for the mission. Finally we discuss the immediate and long term future for the IGSL.
The publication is available online.
Bibtex entry for this abstract

Discrete Source Classifier performance and status report
Author: K. Smith, C.A.L. Bailer-Jones, P. Tsalmantza
Document code: GAIA-C8-TN-MPIA-KS-019
Summary: This report summarizes the current status of the Discrete Source Classifier (DSC), part of the CU8 Apsis system. Various issues surrounding the current design performance are discussed, as well as plans for developments in the near future.
The publication is available online.
Bibtex entry for this abstract

Semi-empirical library of galaxy spectra from SDSS
Author: P. Tsalmantza, M. Kontizas, C.A.L. Bailer-Jones, et al.
Document code: GAIA-C8-TN-UOA-PAT-003
Summary: This document describes the construction of a semi-empirical library of galaxy spectra that will be used in cycle 4 of simulations. The library consists of approximately 33600 spectra from SDSS which were compared through 2-fitting with the second library of synthetic galaxy spectra (GAIA-C8-TN-UOA-PAT-002-1) and found in good agreement with them. Based on this comparison the observational spectra were extended to the Gaia wavelength range and known astrophysical parameters were assigned to them.
The publication is available online.
Bibtex entry for this abstract

Analysis of Stellar Parameter Uncertainty Estimates from Bootstrapping Neural Networks
Author: P.G. Willemsen, C.A.L. Bailer-Jones, T.A. Kaempf
Document code: ICAP-PW-004
Summary: The derivation of stellar parameters by automated methods is only meaningful if some measure of confidence for the predicted value can be stated. In this work we introduce one possible method for obtaining standard errors and confidence intervals for stellar parameters Teff , log g, [Fe/H] and extinction Av as predicted by neural networks (NN). We applied the bootstrapping method to a feedforward NN for Blind Testing Cycle 2 medium band 1X and 2F photometry for end of mission magnitudes G=15 and 19 mag. We further tested whether the parametrization results can be improved if multiple noisy versions of a filter flux vector (for a given astrophysical parameter) are used in the training set. The obtained results show that the bootstrap standard errors only change significantly if the overall signal to noise ratio is high.
The publication is available online.
Bibtex entry for this abstract