1. Leicester Database & Archive Service J. D. Law-Green, S. W. Poulton, J. Osborne, R. S. Warwick Dept. of Physics & Astronomy, University of Leicester LEDAS Data Holdings LEDAS DATA Transfers MB transferred per month What is LEDAS? The Leicester Database and Archive Service (LEDAS) is an on- line astronomical database service providing access to catalogues and data product archives with an emphasis towards high-energy astrophysics. LEDAS provides UK access to the ROSAT Public Data Archive, the ASCA Public Data Archive, the Ginga Products Archive, and now to the Chandra Science Archive. LEDAS has been a public facility since 1992. The LEDAS cluster now stores 460 GB of catalogue and archive data, a volume growing at over 150 GB/yr. The service is very popular, receiving c.18,000 web hits per month, and providing data downloads of c.1.3 GB per month. LEDAS has a full-time support scientist who can be contacted at ledas-help@star.le.ac.uk. Questions about the archive databases and requests for new datasets/services are welcomed. ledas-help@star.le.ac.uk LEDAS Services LEDAS provides a number of on-line database services:- ARNIE: a web search interface to over 200 astronomical catalogues. Complex searches can be also be performed through a command-line interface or the STARLINK image viewer GAIA. The catalogues include sky surveys at several wavelengths, X-ray plasma physics data and X-ray satellite observing logs. BLASTA: A companion search engine to ARNIE for large catalogues, providing enhanced output options. DSS: A fast web interface to the Digitised Sky Survey, providing images of the selected region of sky in GIF, FITS or HDS format. Images can be requested individually, or in batches from preloaded source list Software: A range of X-ray reduction and modelling software packages are available for download from LEDAS, including HEASoft, PIMMS and CIAO. X-ray Product Archive: Calibrated public data products (images, spectra, light curves) from ASCA, Ginga, ROSAT and now Chandra are available for download from LEDAS. Image previews are available on-line to allow rapid selection of the desired data. The Chandra Data Archive: LEDAS provides extensive support to UK users of Chandra, NASA’s flagship X-ray observatory mission. We host an up- to-date mirror of the Chandra Science website hosted at the Harvard Center for Astrophysics, which hosts in-depth information on current observing status and resources for Chandra data reduction and analysis. We provide a UK download site for CIAO, the primary data reduction software package for Chandra. LEDAS hosts the only mirror outside the United States of the Chandra Data Archive. We provide fast access for UK users to download raw and processed public-domain Chandra data via a simple web interface. The Archive currently stores more than 100GB of data, an amount growing by approx. 4GB per week. Further enhancements, including mirroring of basic calibration data, will be implemented shortly. Images and calibrated data from the ASCA Public Archive Chandra image of Eta Carinae (courtesy of CXC) LEDAS Site: http://ledas-www.star.le.ac.uk/http://ledas-www.star.le.ac.uk/ Chandra Archive:http://ledas-cxc.star.le.ac.uk/http://ledas-cxc.star.le.ac.uk/ Web URLs: