Reprinted from ASTROPHYSICS AND SPACE SCIENCE, 280:1-2.
Astrometry from space was performed for the first time and with great success by the ESA Hipparcos satellite (1989-93). This mission was designed as an as trometry mission, but the use of a photon counting detector made it possible to produce very important photometric results: the most accurate astronomical pho tometry ever by the main Hipparcos mission in a very broad band of 120000 stars, and the two-colour Tycho-2 photometry of 2.5 million stars. The cornerstone ESA mission GAIA was approved in October 2000 for launch not later than 2012. This mission will use CCDs in time-delayed integration mode instead of the photo-cathode detectors used in Hipparcos. Due to the higher quantum efficiency of the CCDs, simultaneous integration of many stars, and larger tele scope apertures GAIA will utilize the star light a million times more efficiently than Hipparcos, resulting in astrometry and multi-colour photometry for one billion stars. GAIA photometry is crucial for the scientific utilization of the astrometric results, and the photometric data have a high scientific content in themselves.
Preface. Meeting Photo.
1. GAIA: An Astrometric and Photometric Survey of our Galaxy; M.A.C. Perryman.
2. GAIA Photometry: Selected Topics; E. Høg. 3.Determination of Stellar Parameters with GAIA; C.A.L. Bailer-Jones. 4. GAIA Photometric System: Evaluation of Performance; V. Vansevicius, et al. 5. GAIA Photometric System: Simultaneous 4-D Parameterization; A. Bridzius, V. Vansevicius. 6. GAIA Photometric System: Simulation of Photometric Observations; V. Deveikis, et al. 7. The Spectro Point Spread Function for GAIA; C. Fabricius, L. Lindegren. 8. On the Tolerances of Filters for GAIA Medium Band Photometric System; A. Kazlauskas, et al. 9. Bandwidth Effects in the 3G Photometric System; J. Sudzius, V. Vansevicius. 10. Transformations between Vilnius and Strömgren Photometric Systems; J. Knude, N. Kaltcheva. 11. Systematic Errors of High-Precision Photometric Catalogues; A. Mironov, A. Zakhavor. 12. The Asiago Database on Photometric Systems (ADPS) and the Design of the GAIA Photometric System; M. Fiorucci, U. Munari. 13. BaSeL: A Library of Synthetic Spectra and Colours for GAIA; E. Lastennet, et al. 14. Japanese Astrometry Satellite Mission for Infrared Exploration; N. Gouda, et al.
GAIA: Astrophysical Issues.
15. Methods to Account for Interstellar Extinction; J. Knude. 16. 3-D Structure of the Galactic Interstellar Matter: A Contribution from GAIA; J. Sudzius, et al. 17. A Synthetic Map of the Galactic InterstellarExtinction; O. Malkov, E. Kilpio. 18. Diffuse Interstellar Band at 862 nm as a Reddening Tracer for GAIA; A. Kucinskas, V. Vansevicius. 19. GAIA and Population II Visual Binaries; A. Bartkevicius, A. Gudas. 20. Unresolved Binaries and the Initial Mass Function; O. Malkov. 21. Binary Star Detection with the GAIA Radial Velocity Spectrometer; V. Deveikis, et al. 22. Detection of Extra-Solar Planets by GAIA Photometry; E. Høg. 23. a-process Elements in the Galaxy: A Possible GAIA Contribution; G. Tautvaišiene, B. Edvardsson. 24. Asymptotic Giant Branch Stars and Tracers of Star Formation Histories: the GAIA Context; A. Kucinskas, et al. 25. Globular Clusters in the Large Magellanic Cloud: An Impact from GAIA Photometry; A. Kucinskas, et al. 26. GAIA and the Extragalactic Distance Scale; G.A. Tammann, B. Reindl.
27. Ground Based Testing of the GAIA Filters; C. Flynn. 28. General Discussion and Photometric System for GAIA; E. Høg.