AstroGrid - Part of the European Virtual Observatory

by Peter M Allan

AstroGrid is the UK’s implementation of the concept of a virtual observatory - being able to get at all the world’s astronomical data directly from your desktop computer. It has been developed over the last 5 years with contributions from the Rutherford Appleton Laboratory and the universities of Edinburgh, Leicester, Cambridge, University College London (Mullard Space Science Laboratory), Manchester (Jodrell Bank Observatory), Queen’s University Belfast, Bristol, Exeter, Portsmouth and Leeds.

The underlying concept is to provide data and computational services as grid services, such that a distributed data grid is built. The focus is on the provision of access to data, rather than on access to supercomputing power, although that can be one of the services offered. Within the UK, AstroGrid provides access to the large astronomical data resources held at the first six of the institutions listed above. If it did just this, AstroGrid would be useful, but not revolutionary. In fact, AstroGrid is an active participant in the International Virtual Observatory Alliance, a group dedicated to defining a truly international set of standards for grid-enabling access to astronomical data world wide. At the European level, AstroGrid is an active partner in Euro-VO, and leads the VO-Tech part of this Framework 6 project.

There are several virtual observatory projects around the world. AstroGrid has taken the route of deliberately deciding what astronomers really needed to make a major step forwards in their ability to analyse their data, and to build the infrastructure to do this. Some of the infrastructure has been a challenge to design and build, but we now have a system that can be used by astronomers in earnest. It is starting to be used to do real science.

The fundamental architecture behind AstroGrid consists of a set of web services with a workflow system that makes use of these services. In order to process data using AstroGrid, an astronomer builds a workflow and then executes it. They do not need to explicitly get the data from a data archive; the web services handle that. They do not need to be concerned with the storage of intermediate data; that is held in an area called MySpace. Depending on what the astronomer wants to be the result of some data search and processing, there may or may not be a requirement to have final data returned to the user’s desktop. A typical simple workflow would be to get data from A and B, processes them at C and store the results at D. The actual location of A,B,C and D are not important to the user, only the result is.

As an example of the ease with which data can be obtained, as a test I recently tried to get some optical data on the quasar 3C273 (a famous object to astronomers). With a total of about ten clicks of the mouse and typing “3C273” (the system knows its position on the sky) I was offered data from the Hubble Telescope, which I chose to download from the archive in the USA to MySpace. I could then display the images on my computer. This is a fairly simple example of what is possible, but it demonstrates that a wealth of data are only a few mouse clicks away. This makes it much easier than in the past to think of an idea, gather the data needed to test this, and do the analysis. The aim is to promote asking new questions and actually testing them because it is now easy to do so.

The Astrogrid science service allows a user to make a movie of solar images by means of a simple interface.

Most of what AstroGrid provides in the way of data processing can already be done by existing means, with enough effort. The key is the words “with enough effort”. If a task will take a lot of effort to do, it may not be attempted if the value of the results is unclear. Speeding up the time from idea to result will actually get new science done, because now it is worth asking new questions. The area in which AstroGrid will enable science that really was not practical before is in responding to sudden events in the sky that require a rapid response before they fade from view. The problem of gamma-ray burst sources is such a problem of current interest. These objects suddenly emit in gamma–rays what appears to be the total energy output of a whole galaxy in a few minutes. They then fade rapidly from view, making it very difficult to observe with other telescopes. AstroGrid allows an automated rapid response system to be built to gather those vital follow-up observations in time.

The facilities of AstroGrid are available via a web browser or by using a workbench on your desktop. These are described at www.astrogrid.org, from where the workbench can be downloaded.

While AstroGrid currently provides access to a large variety of data resources and it has some useful applications, it does not currently have a large number of applications for processing those data. These will come along in the future. However, the infrastructure is a completely open one and there is a simple way in which existing free standing applications can be hooked into AstroGrid, so there is considerable scope for a rapid increase in applications software, given the effort to do so.

Link:
http://www.astrogrid.org/

Please contact:
Peter M. Allan, Space Science and Technology Department, CCLRC, UK
E-mail: P.M.Allanrl.ac.uk