The paper presents an overview of the problems astronomical data centers are facing today.

When one organizes a colloquium, one can do some fairly outrageous things, like putting ones own contribution first . However as an excuse for such a procedure, I shall say that I want really not to discuss that much what the C.D.S. itself does, but what problems we have been confronted with, specially those which came up since the last Strasbourg colloquium, or which got more complicated to handle.

More than 250 machine-readable catalogs of stars and extended celestial objects are now available at the NASA/Goddard Space Flight Center (GSFC) as the result of over a decade of catalog acquisition , verification and documentation. Retrieval programs are described which permit the user to obtain from a remote terminal bibliographical listings for stars; to find all celestial objects from a given list that are within a defined angular separation from each object in another list; to plot celestial objects on overlays for sky survey plate areas; and to search selected catalogs for objects by criteria of position , identification number, magnitude or spectral type.

On the basis of the current French-Soviet cooperation in science and technology, the Astronomical Council of the U. S. S. R. Academy of Sciences and the Strasbourg Center signed in 1977 an agreement on setting up the Soviet Center of Astronomical Data as its filial branch. The Soviet Center was created on the basis of a computation center at the Zvenigorod station of the Astronomical Council of the U. S. S. R. Academy of Sciences, which had already had considerable experience of working with stellar catalogues. In 1979 the Center was equipped with a EC-1033 computer.

The methods of controlling and disseminating astronomical data at the Kanazawa Data Center (operated under the Computer Center of the Kanazawa Institute of Technology) are described. Discussions include the coded data descriptions used in conjunction with a file processing language. Problems concerning remote data access are also discussed, and the future plan presented.

In 1968 the Data Centre was established in the Central Institute for Astrophysics of the Academy of Sciences(CIAP) of the German Democratic Republic. Its task was essentially the analysis of astronomical observations and the elaboration of theoretical models for astronomical problems.

In 1974,a cooperation was started between our institution and the Stellar Data Centre at Strasbourg.

The IUE project is described, with special emphasis on the IUE data management and archive retrieval.

This paper briefly describes a more specific data center providing also a service to the astronomical community, or more precisely a group of data centers dedicated to a given instrument.

This instrument is the IUE ( International Ultraviolet Explorer) launched on Jan. 26, 1978 and collecting since then spectral images of all kinds of celestial objects in the ultraviolet wavelength range.

A computer data base of infrared astronomical observations has been established at NASA/Goddard Space Flight Center. It contains a summary of all infrared (1µm-1000µm) observations of celestial sources outside the solar system, published in the major scientific journals since 1960, as well as the contents of infrared surveys and catalogs. A Catalog of Infrared Observations (CIO) has been developed from the data base in printed and magnetic tape versions. A bibliographic Guide to the Infrared Astronomical Literature, and an Atlas of Infrared Source Names and Positions will be published in conjunction with the catalog. Future plans include development of an interactive data system at Goddard which will give a user direct access to the computerized data.

Users of time and polar motion information have requirements for data which are somewhat different from those usually considered for astronomical data files. Because of these requirements, it is necessary to provide immediate access to the latest information on Earth orientation and even predictions of future orientation. For other applications where data of the highest accuracy is required with little concern for the delay between observations and the determination o f the required information, a more traditional approach may be used. To meet all of these needs a versatile automated data retrieval system is demanded. The U. S. Naval observatory is now implementinq such a system in the area of Earth orientation information and for precise time and time interval applications. Data are available through a series of weekly, monthly, and annual reports, as well as through a digital communications link to Time Service machine-readable files.

The combined role of NSSDC and WDC-A-R&S in collecting, preserving and disseminating data from 10 years of X-ray observations is presented along with a brief history of the organizations.

The majority of entries for MK Spectral Classifications in the Kennedy & Buscombe (1974) catalogue referred to stars brighter than 9th magnitude with H. D. numbers. Accordingly, the file was arranged in sequence corresponding to right ascension for 1900, although the co-ordinates were actually listed for the epoch 2000, in accordance with an earlier precept established in the IAU.

Euronet is one of the world's most recent networks created for data transmission. Sponsored by the Commission of the European Communities, Euronet was officially opened for traffic, at the beginning of 1980, in the buildings of the European Parliament in Strasbourg.

Six VAX-11/780 computers have been set up at different centres of astronomical research throughout the United Kingdom. These computers are solely for the use of astronomers and they are linked together using special telephone lines. They are proving to be a powerful tool, both in the reduction of astronomical images and in the subsequent data analysis.

ASTRONET, the network for analysis and retrieval of astronomical data planned in Italy, is described with regard to the organization of the network, the hardware, and the standard software environment. ASTRONET starts with four VAX centers operating within 1981, to be expanded to six within 1983.

The network includes colour graphics and PDS plates digitization facilities. The software and graphics standards will be set as compatible as possible to major existing astronomical standards. ASTRONET is planned to be operative within 1983 as an open international astronomical facility.

Broad outlines of a permanent service involved in the prompt dissemenition of solar and geophysical data.

The Solar Activity has an effect on several modern technics. For instance, during a transient increase of solar UV flux, the trajectory of a low perigee satellite can slightly change, a ionospheric communication link can fade out or some scientific program can only be carried out during some outburst of the solar activity.

It is estimated that up to 100 Gbytes of primary data from digital detectors have to be stored each year. The amount of reduced data is at least one order of magnitude smaller. Although the storage density for magnetic recording can be made higher, only the optical technic can provide a substantial denser medium than the photographic emulsion. It seems likely that optical read-only devices will be developed for archival storage of data in this decade. Magnetic recording of data will still be preferred whenever changing of the information is important.

In this review paper on software techniques, the concepts of “software system” and “data base interface” are defined in the context of astronomical data analysis requirements. Principles of software desiqn and maintainance over are discussed.

A deliberate effort was made to stay as close as possible to the astronomical application and not deviate too much into computer science.