Transcript Leicester Database & Archive Service What is LEDAS? LEDAS and AstroGrid

Leicester Database & Archive Service
J. D. Law-Green, J. P. Osborne, R. S. Warwick
X-Ray & Observational Astronomy Group, University of Leicester
What is LEDAS?
LEDAS and AstroGrid
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.
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.
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.
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 has a full-time developer /
support scientist who can be contacted
at [email protected]. Comments
and questions about the archive
databases and requests for new
datasets/services are welcomed.
LEDAS Data Holdings
XMM Other ROSAT
50GB
23GB
65GB
ASCA
121GB
BLASTA
165GB
DSS
870GB
Chandra
366GB
Fig. 1: Current LEDAS Data Holdings
DSS: Digitised Sky Survey
Chandra: Chandra Public Archive
XMM: XMM Serendipitous Source Catalogue (1XMM) archive
ASCA: ASCA Science Archive
ROSAT: ROSAT Public Archive
BLASTA: Large catalogues (including GSC, 2MASS)
Other: Other mission archives, including Ginga, Einstein
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.
New LEDAS Services
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 Javabased search interface, see
http://chandra.ledas.ac.uk/
Other LEDAS work
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).
http://www.ledas.ac.uk/