Miguel A. Albrecht

Information & on-line data in astronomy

1. Facets and Challenges of the Information Technology Evolution A. Heck. 2. The Compton Gamma-Ray Observatory Archive P. Barrett. 3. Data from the X-Ray Observatory ROSAT H.U. Zimmermann, et al. 4. The Einstein On-Line Service D.E. Harris, C.S. Grant. 5. The EUVE Archive Centre for Extreme Ultraviolet Astrophysics. 6. The IUE Archives M. Barylak, et al. 7. Building the Archive Facility of the ESO Very Large Telescope M.A. Albrecht, et al. 8. Deep Near Infra-red Survey of the Southern Sky (DENIS) E. Deul, et al. 9. Data from the Cosmic Background Explorer (COBE) D. Leisawitz, J.C. Mather. 10. The NASA/IPAC Extragalactic Database G. Helou, et al. 11. LEDA: The Lyon-Meudon Extragalactic Database G. Paturel, et al. 12. The Database for Galactic Open Clusters (BDA) J.-C. Mermilliod. 13. The HEASARC Facility The HEASARC Team. 14. IPAC Datasets and On-Line Services R. Ebert, et al. 15. The Archives of the Canadian Astronomy Data Centre D.R. Crabtree, et al. 16. A Global Perspective on Astronomical Data and Information: The Strasbourg Astronomical Data Centre (CDS) D. Egret, et al. 17. Data Holdings in the ADS S.S. Murray, et al. 18. The European Space Information System (ESIS) P. Giommi, S.G. Ansari. 19. The Stars Family: An Example of Comprehensive Yellow-Page Services A. Heck. 20. Library Information Services U. Michold, et al. 21. How to Make your Information Available on the Network M.A. Albrecht, D. Egret. 22. Computer Networking in Astronomy F. Murtagh. 23. Data Storage Technology for Astronomy B. Pirenne, D. Durand. 24. NED and SIMBAD Conventions for Bibliographic Reference Coding M. Schmitz, et al.

VLT Data Flow System: from concepts to operations

In order to realize the optimal scientific return from the VLT, ESO has undertaken to develop an end-to-end data flow system from proposal entry to science archive. The VLT Data Flow System (DFS) is being designed and implemented by the ESO Data Management and Operations Division in collaboration with VLT and Instrumentation Divisions. Tests of the DFS started in October 1996 on ESOs New Technology Telescope. Since then, prototypes of the Phase 2 Proposal Entry System, VLT Control System Interface, Data Pipelines, On-line Data Archive, Data Quality Control and Science Archive System have been tested. Several major DFS components have been run under operational conditions since February 1997. This paper describes the current status of the VLT DFS, the technological and operational challenges of such a system and the planing for VLT operations beginning in early 1999.

ESO data flow system in operations: closing the data loop

On 1 April 1999, the first unit telescope (ANTU) of the ESO VLT began science operations. Two new instruments (FORS-1 for optical imaging and spectroscopy and ISAAC for IR imaging and spectroscopy) were offered in a mix of 50% visitor mode and 50% service mode. A Phase-I and Phase-II proposal and observation preparation process was conducted from 1 October 1998 until the middle of March 1999 involving approximately 280 proposals. A total of 1768 Observation Blocks for 83 approved service mode programs were scheduled and executed between 1 April and 1 October 1999. The resultant raw science and calibration data were subjected to quality control in Garching and released to the ESO user community starting from 15 June 1999 along with pipeline processed data products for a subset of instrument modes. The data flow loop for the first LT telescope is closed. The current operational VLT data flow system and the developments for the remainder of the VLT will be presented in the light of the first year of operational experience.

VLT Data Flow System: the NTT prototype experience

The data flow system (DFS) for the ESO VLT provides a global system approach to the flow of science related data in the VLT environment. It includes components for preparation and scheduling of observations, archiving of data, pipeline data reduction and quality control. Standardized data structures serve as carriers for the exchange of information units between the DFS subsystems and VLT users and operators. Prototypes of the system were installed and tested at the New Technology Telescope. They helped us to clarify the astronomical requirements and check the new concepts introduced to meet the ambitious goals of the VLT. The experience gained from these tests is discussed.

How to make your information available on the network

Scientists producing new datasets or astronomical catalogues are encouraged to make their computer-readable material and documentation available for distribution to the worldwide astronomical community. The usual procedure is by depositing a copy in one of the international astronomical data centers (see, e.g. CDS, chapter 16 in this volume), while simultaneously submitting a paper describing the results and procedure to a scientific journal. The journal’s refereeing process will check the scientific contents while data centers normally check the technical consistency of the digital material, thus ensuring the quality of the publication.

VLT science archive system

The ESO very large telescope (VLT) will deliver a science archive of astronomical observations well exceeding the 80 Terabytes mark already within its first six years of operations. ESO is undertaking the design and development of both on-line and off-line archive facilities. This paper reviews the current planning and development state of the VLT science archive project.

Building the archive facility of the ESO Very Large Telescope

The experience gained while building a science archive for the NTT (Albrecht & Grosbol, 1992) has shown that the main problems lie less in solving the technical issues than in making the observatory and the community aware of the advantages of a traceable and predictable telescope operation. Traceable operations allow to quickly understand the source of problems and is the basis for high-quality, detailed scientific analysis of the data. Predictable operations allows for good observing programme preparation and is the basis for high efficiency.

The EUVE Archive

NASA’s Extreme Ultra Violet Explorer (EUVE) satellite was launched on June 7, 1992 from Cape Canaveral, Florida on a Delta II rocket. The payload contains three EUV scanning telescopes equipped with imaging detectors as well as a Deep Survey Spectrometer instrument which divides the light from a fourth telescope between an imaging detector and three EUV spectrometers.

Information in astronomy: tackling the heterogeneity factor

Over the past two decades, the increasing efficiency of cameras and photon collecting devices used by astronomers has generated an unprecedented accumulation of data. This phenomenon, a characteristic of the so called information era, has not been accompanied by the corresponding development of tools and systems to handle, analyse, store, retrieve and disseminate observational data. The result being that only a small part of the data is immediately used and published, in the investigations for which it was planned. At the same time, the always larger investments involved in modern telescopes or space missions have raised the question of cost-to-benefit ratio in the management of observing facilities — in particular when it is rather usual to find a large pressure factor on the usage of these facilities (e.g. for HST and the ESO NTT there are about four times more observing proposals than time available).