Leicester Database & Archive Service

J. D. Law-Green, J. P. Osborne, R. S. WarwickX-Ray & Observational Astronomy Group, University of Leicester

What is LEDAS?

New LEDAS Services

LEDAS and AstroGrid

http://www.ledas.ac.uk/

Other LEDAS work

XMM50GB

Other23GB

ROSAT65GB ASCA

121GB

BLASTA165GB

Chandra366GB

DSS870GB

The Leicester Database & Archive System (LEDAS) is an online astronomical database service providing access to catalogues and data product archives with an emphasis towards high-energy astrophysics. LEDAS provides UK access to the 1XMM archive, Chandra Science Archive, the ASCA Public Data Archive and the Ginga Products Archive.

LEDAS has been a public facility since 1992. The LEDAS cluster now stores 1.6TB of catalogue and archive data (see Figure 1) and the data volume continues to grow rapidly. The service is very popular, receiving c.25,000 web hits per month, and providing data downloads of ~2 GB per month.

LEDAS has a full-time developer / support scientist who can be contacted at ledas-help@star.le.ac.uk. Comments and questions about the archive databases and requests for new datasets/services are welcomed.

Fig. 1: Current LEDAS Data Holdings

Fig. 2: New archive hardware installed at LEDAS. The new servers have a total storage capacity of 6TB.

Fig. 3: New archive web interface (ARNIE v5) showing results of search on 1XMM catalogue.

A number of LEDAS services have recently been expanded or enhanced:-

ARNIE: a web search interface to over 300 astronomical catalogues. The new version (v5) can now search multiple catalogues simultaneously, output several formats including VOTable, and provide interactive graphical displays of results using VOPlot and Aladin.

DSS: Web access to images from the Digitised Sky Survey. The latest update provides access to the new higher resolution DSS-II images, with optional coordinate grid overlays.

XMM: LEDAS now provides access to the public data holdings of the XMM Serendipitous Source Survey (1XMM), the first wide-area detection catalogue by the XMM-Newton mission. Catalogues, calibrated images and observing logs can be accessed online using the simple search interface (see Fig. 3).

Chandra: LEDAS hosts the only mirror outside the United States of the Chandra Data Archive. We provide fast, local access for UK users to download raw and processed public-domain data. The Archive currently stores 360GB of data, an amount growing by approx. 4GB/week. The LEDAS archive now has a fully-featured Java-based search interface, see http://chandra.ledas.ac.uk/

AstroGrid is a £3.7M eScience project funded by PPARC to create a protoype Virtual Observatory for UK astronomers. We are working extensively with AstroGrid developers to enable VO access to LEDAS datasets, providing a Web Services (SOAP) interface to query LEDAS remotely. LEDAS is the first data-centre outside the AG consortium to undertake this work.

This will be followed by further AstroGrid components, such as an interactive web “portal” and MySpace server (allowing users to cache search results on a storage server at LEDAS for further analysis).

LEDAS is involved in other eScience projects:-

Swift: Leicester will host the UK Data Centre for the Swift Gamma-Ray Burst Explorer mission. The UKDC will archive Swift observations and provide public access to the data. LEDAS is currently providing systems support to the UKDC. The UKDC will build on LEDAS infrastructure and software.

WASP: The Wide Area Sky Patrol is a collaboration to build a system of robotic survey telescopes. Objectives include discovery of extrasolar planets by transit method, and detection of transient or moving objects such as gamma-ray bursts or NEOs. The WASP dataset will be an invaluable resource for time-domain astrophysics.

LEDAS is assisting with an experimental WASP data archive, to develop techniques in handling very large (TB-sized) databases. A public archive interface at Leicester is foreseen once WASP enters routine service.

Fig. 4: SuperWASP cameras (image courtesy www.superwasp.org).

LEDAS Data Holdings

DSS: Digitised Sky Survey Chandra: Chandra Public ArchiveXMM: XMM Serendipitous Source Catalogue (1XMM) archiveASCA: ASCA Science ArchiveROSAT: ROSAT Public ArchiveBLASTA: Large catalogues (including GSC, 2MASS)Other: Other mission archives, including Ginga, Einstein