Background.

The ST-ECF/ESO Archive currently contains more than 10.0 Terabytes of scientific data obtained with the ESA/NASA HST, with the ESO NTT, VLT and with the Wide Field Imager on the ESO/MPI 2.2m Telescope. The growth rate is 4.5 Tbytes per year ramping to 6.0 Tbytes/yr within the next two years. In addition to 'public' data arising from General Observer programmes whose 1 year proprietary period has elapsed, the HST Archive contains some large datasets resulting from programmes approved with a reduced or nonexistent proprietary period - this includes 'parallel' data from a second instrument obtained simultaneously with pointed observations by the primary instrument. Large public datasets are expected to accumulate even faster during the second decade of HST operations.

In addition, network connection allows Archive Users to retrieve data from other active Archive Centers (e.g. ISO). Intermediate data sets can be staged on fast access robotic devices. This unique (in size and quality) collection of diversified astronomical data can now be seen as a "virtual" observatory, capable of responding to requirements for observations as a "real" first-class telescope.

The ASTROVIRTEL Project, supported by the European Commission and managed by the ST-ECF on behalf of ESA and ESO, is aimed at enhancing the scientific return of the ST-ECF/ESO Archive. It offers the possibility to European Users to exploit it as a virtual telescope, retrieving and analyzing large quantities of data with the assistance of the Archive operators and personnel. The first call for proposals was issued in April 2000 and the second in April 2001 with a deadline for submission of June 15, 2001.

How does it work?

• Genuine "Archive Research Proposals", based on the use of data contained in (or accessible via) the ST-ECF/ESO Archive are solicited from scientists belonging to EC Member and Associated States.

  The deadline for submission is June 17, 2002.

  The ASTROVIRTEL Proposal submission forms are a modified version of the existing HST Archive Proposal ones.

The ASTROVIRTEL Selection Panel will select up to six Proposals per year. The selection criteria will be:

• Scientific originality and excellence
• Scientific exploitation of large and multi-instrument data sets
• Particular attention will be given to those research programmes requiring the development of new "mining tools" that might be of general interest to the community.

For the selected proposals ASTROVIRTEL will provide:

• Travel and subsistence for PI and CoI visits to the ST-ECF/ESO Archive Facility for discussing the proposal and planning the development and operation of relevant tools.
• Development and operation of the "mining tools", specifically developed for the proposal
• Retrieval of additional data sets, not locally available
• Support for the analysis and interpretation of the data

Comments and examples.

Up to now, HST Archival Proposals were the prerogative of US Astronomers who can submit them within the normal HST Observing Cycles. The ASTROVIRTEL Project is partly aiming at filling this gap, with two notable differences:

• The Archival Proposals are not limited to HST data.
• The support is mainly offered as services to the Proposers, rather than as pure grants.

The advantages of the ASTROVIRTEL approach are that:

• the "scientific inter-operability" of different Archives will be enhanced on the basis of specific scientific requirements (those contained in the approved Proposals);
• the "mining tools" and the procedures for the management and analysis of the retrieved data sets will become part of the Archive and offered to the community.

Some comments about the first round of ASTROVIRTEL Proposals may clarify the concept.
Eleven proposals were submitted to the first call, out of which five were approved by the Selection Panel (about stellar population(2), solar system(1), galaxies(1), and astroseismology(1)) . During a first visit to the ST-ECF, the science goals of the proposals were discussed with the ASTROVIRTEL and Archive Staff and the specific requirements for an optimal use of the Archive system were identified.
For a wider interaction with the ST-ECF and ESO staff, the proposers are normally invited to give an informal "lunch talk" about the aim of their proposal.
From the first round of interaction, it became immediately evident that a number of "search" capabilities were needed in order to find and retrieve the required data. Although these capabilities were generated by the specific proposals, it was clear that they would have also been very useful for the general Archive user.
For example, one proposal requires a tool that can browse through the data sets of different imaging instruments having a specific and uniform "knowledge" about the photometric characteristics of the data. While such search could have been done manually for small data sets, it becomes prohibitively lengthy for a general search through the entire archive. Similarly, the shape and orientation of the different imaging instruments, normally available only in the handbook, is a vital piece of information to be added to the on-line archives for an efficient cross-correlation of different archives. These capabilities were quickly implemented in a fast prototyping approach and tested with the proposers during their second visit to the ST-ECF. They are now operationally used and later, when properly debugged and made more robust, they will become available to the general user (see querator).

In a questionnaire that the proposers were asked to reply to, they have commented positively this type of approach. In particular the direct interaction with colleagues that know well the Archive system "from the inside" and therefore can propose efficient solutions, has been appreciated.

In view of the evolution from ASTROVIRTEL to a proper "Astrophysical Virtual Observatory", AVO, this type of interaction with genuine Archive projects is instrumental to keep the development of sophisticated software tools very close to the actual science requirements.

Who can apply?

Any research group from EC Member and Associated States can submit a proposal. The primary goal of the project is to enhance the exploitation of the Archive for scientific research. However, proposals for innovative uses of the Archive, e.g. in the field of education and outreach, will also be considered. Interested groups are encouraged to discuss their specific ideas and needs with ASTROVIRTEL [Piero.Benvenuti@eso.org]

What cannot be funded ?

Unfortunately, under this EC scheme (Enhanced Access to Research Infrastructures), individual grants (e.g. post-docs) and the acquisition of additional hardware cannot be funded.

Connection with other EC supported Networks

The evolution of the ASTROVIRTEL Project, its impact on the European community, and in particular the implications and recommendations for an improved inter-operability of different Archives, is routinely discussed within the OPTICON [link] Network, in which an Archive Working Group is being formed. An RTD Proposal for the design and implementation of an Astrophysical Virtual Observatory (AVO), has been submitted to the European Commission.