Visualisation is a powerful tool for understanding the large data sets
typical of astronomical surveys and can reveal unsuspected
relationships and anomalous regions of parameter space which may be
difficult to find programatically. Visualisation is a classic
information technology for optimising scientific return. We are
developing a number of generic on-line visualisation tools as a
component of the Australian Virtual Observatory project. The tools
will be deployed within the framework of the International Virtual
Observatory Alliance (IVOA), and follow agreed-upon standards to make
them accessible by other programs and people. We and our IVOA
partners plan to utilise new information technologies (such as grid
computing and web services) to advance the scientific return of
existing and future instrumentation.
Here we present a new tool - VOlume - which visualises point data.
Visualisation of astronomical data normally requires the local
installation of complex software, the downloading of potentially large
datasets, and very often time-consuming and tedious data format
conversions. VOlume enables the astronomer to visualise data using
just a web browser and plug-in. This is achieved using IVOA standards
which allow us to pass data between Web Services, Java Servlet
Technology and Common Gateway Interface programs. Data from a
catalogue server can be streamed in eXtensible Mark-up Language format
to a servlet which produces Virtual Reality Modeling Language output.
The user selects elements of the catalogue to map to geometry and then
visualises the result in a browser plug-in such as
Cortona or FreeWRL.
Other than requiring an input VOTable format file, VOlume is very
general. While its major use will likely be to display and explore
astronomical source catalogues, it can easily render other important
parameter fields such as the sky and redshift coverage of proposed
surveys or the sampling of the visibility plane by a
For the Virtual Observatory to connect archives around the globe, some standardization is needed. It is not necessary to rework the internal structure of each archive to a common standard, but standards for interfaces to archives and for exchange of data are important.
We report on standardization work currently going on in the AVO and AstroGRID projects in the following areas:
- Exchange formats for tabular data;
- Semantic definitions for quantities in tabular data;
- Identification of user and authorization to use resources;
- Query interfaces to archives;
- Catalogues of data resources.
Discussion on standards is ongoing among all Virtual Observatory projects.
Current astronomical facilities on the WWW support anonymous access to public-domain resources with very limited workflows. To meet even current aspirations, the Virtual Observatory needs to operate extensive workflows that also include access to restricted resources.
AstroGrid (see http://www.astrogrid.org/), a UK eScience project with collaborating groups drawn from the major UK data archive centres, is currently creating the UK's virtual observatory (Lawrence, 2002, these proceedings). We present use cases from AstroGrid's survey of requirements that show a need for a pervasive infrastructure for identifying users and controlling access to facilities and data. We describe in outline AstroGrid's architecture for this infrastructure.
AVO Work Area 2 consists of deployment and demonstration of an interoperability prototype. Access to archives of all the partners (ESO, ESA, AstroGrid, Terapix, Jodrell Bank) is implemented via the CDS data federation and integration tools: VizieR and Aladin. The prototype is available for science usage and more functionalities, based in particular on the usage of Uniform Content Descriptors (UCDs) for data mining, will be developed. Case by case discussion with data providers will help to establish a set of practical recommendations for interoperability. Science requirements and new technologies studied by the other AVO work Areas will also be tested. Discussions on standards are ongoing among all VO projects.
The advent of new large CCD array cameras necessitates computing systems that are highly optimized but also enable flexibility of operation and ease of programming. We describe `UltraDAS', a CCD-control and data-acquisition system for the Isaac Newton Group of Telescopes that achieves these aims by combining high-performance detector- controllers with modern programming techniques on current UNIX workstations.
The computing equipment of the 2.5-m Isaac Newton Telescope and the 1.0-m Jacobus Kapteyn Telescope is being upgraded to improve improve observing efficiency and ease of use, and to reduce maintenance and operation costs. These upgrades have been staged over a period of two years to reduce the impact on operations. Elements of this architecture will be used in the forthcoming upgrades to the 4.2-m William Herschel Telescope. The revised systems have allowed the introduction of a major new instrument for the INT: the Wide Field Camera, shortly to be equipped with a mosaic of four 4096 by 2048 EEV CCDs. On the JKT, the new equipment paves the way for remote operation.