The ESO Imaging Survey is being carried out to help the selection of targets for the first year of operation of VLT. This paper describes the motivation, field and filter selection, and data reduction pipeline. Data for the first completed patch, in the form of astrometric and photometric calibrated pixel maps, single-frame catalogs, on-line coadded section images and further information on the project are available on the World Wide Web at "http://www.eso.org/eis''.
Preliminary evaluation of the data shows that the overall quality of the data is good and the completeness limit of the extracted catalogs is sufficiently deep to meet the science requirements of EIS. Furthermore, the results for the other patches should improve as the observing conditions were considerably better than those in the period of patch A observations.
The final and complete release of the data products of EIS is scheduled as follows: 1) EIS-wide, except the U-band: July 31, 1998, before the first call for proposals for the VLT; 2) EIS-deep and EIS-wide U-band on December 31, 1998.
These data were taken at the New Technology Telescope (NTT) at the ESO La Silla Observatory under the ESO program identifications 59.A-9005(A) and 60.A-9005(A). We thank all the people directly or indirectly involved in the ESO Imaging Survey effort. In particular, all the members of the EIS Working Group for the innumerable suggestions and constructive criticisms, the ESO Archive Group, in particular M. Albrecht, for their support and for making available the computer facilities, ST-ECF for allowing some members of its staff to contribute to this enterprise. We also thank the Directors of all observatories and institutes listed in this paper as affiliations for allowing the participation of some of their staff in this project and for suggesting some of their students and post-docs to apply to the EIS visitor program. Special thanks to G. Miley, who facilitated the participation of ED in the project and for helping us secure observations from the Dutch 0.9 m telescope. To the Geneva Observatory, in particular G. Burki, for monitoring the extinction during most of the EIS observations. To the NTT team for their help. We are also grateful to N. Kaiser for the software and to the DENIS consortium for making available some of their survey data. The DENIS project development was made possible thanks to the contributions of a number of researchers, engineers and technicians in various institutes. The DENIS project is supported by the SCIENCE and Human Capital and Mobility plans of the European Commision under the grants CT920791 and CT940627, by the French Institut National des Sciences de l'Univers, the Education Ministry and the Centre National de la Recherche Scientifique, in Germany by the State of Baden-Wurttemberg, in Spain by the DGICYT, in Italy by the Consiglio Nazionale delle Richerche, by the Austrian Fonds zur Förderung der wissenschaftlichen Forschung und Bundesministerium für Wissenschaft und Forschung, in Brazil by the Fundation for the development of Scientific Research of the State of São Paulo (FAPESP), and by the Hungarian OTKA grants F-4239 and F-013990 and the ESO C & EE grant A-04-046. Special thanks to A. Baker, D. Clements, S. Coté, E. Huizinga and J. Rönnback, former ESO fellows and visitors for their contribution in the early phases of the EIS project. Our special thanks to the efforts of A. Renzini, VLT Programme Scientist, for his scientific input, support and dedication in making this project a success. Finally, we would like to thank ESO's Director General Riccardo Giacconi for making this effort possible.
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