What is the NVO?
About Virtual Observatories
Astronomy faces a data avalanche. Breakthroughs in telescope, detector, and computer technology allow astronomical surveys to produce terabytes of images and catalogs. These datasets will cover the sky in different wavebands, from gamma- and X-rays, optical, infrared, through to radio. In a few years it will be easier to "dial-up" a part of the sky than wait many months to access a telescope. With the advent of inexpensive storage technologies and the availability of high-speed networks, the concept of multi-terabyte on-line databases interoperating seamlessly is no longer outlandish. More and more catalogs will be interlinked, query engines will become more and more sophisticated, and the research results from on-line data will be just as rich as that from "real" telescopes. Moore’s law is driving astronomy even further: the planned Large Synoptic Survey Telescope will produce over 10 petabytes per year by 2008! These technological developments will fundamentally change the way astronomy is done. These changes will have dramatic effects on the sociology of astronomy itself.
The US National Virtual Observatory
In August 2001, the US National Science Foundation awarded five-year funding to a collaboration "Framework for the National Virtual Observatory", under its Information Technology Research program. This web site presents the work under that grant.
The collaboration is for a framework; thus our output is NOT a Virtual Observatory, but rather research about how such a thing could be made. However, in expectation and hope of such a program, we are not planning in a vacuum, but rather simultaneously implementing and planning in synergy with the community.
Some in the astronomical community feel that information technology should not be explicitly funded when there are telescopes and satellites to be funded: however, we point out that the NSF grant is not from Astronomical Sciences, but rather from Computer and Information Sciences.
Standards
The NVO is making astronomical data easier to use through the creation and adoption of standards. Standards make life easy in many ways, for example the universal metric system of units or the HTTP standard that drives the web economy.
An NVO standard that has been adopted worldwide in the VO community is VOTable, a way to represent a table of data in XML with good metadata about the semantic meaning of the data. From this was derived a standard service—ConeSearch—to find out about sky-located objects such as stars or images: the input is a cone of space with center and radius, the output is a VOTable that has RA and Dec columns. The extension of this is Simple Image Access, a protocol that allows publication and query of image sets. We also mention here the UCD (Unified Content Descriptor) a simple semantic identifier expressing the meaning of an attribute.
Grid Computing
Traditionally, science progresses through a combination of theoretical and experimental research. Today, these are augmented by the paradigms of simulation and archive-based research, both of which are supported by NVO protocols.
Prototypes
The NVO has built science prototypes to demonstrate that interesting and efficient research can be done by building upon just a few new protocols and standards for data exchange and access. We use these prototypes to validate and steer the course for technology development within the project – the NVO technologies are responsive to science needs. The three prototypes we have implemented thus far are
• A gamma-ray burst event follow-up service
• A brown dwarf candidate search service
• A galaxy morphology analysis service
These new standards for astronomical data are for access, publishing, discovery, and interoperability, and are being developed in cooperatively with the astronomical community. The emphasis is on maximum return for minimal change in procedure—from either publishers or consumers of data. Your input is welcome; please contact feedback at us-vo.org.
The NVO Project is working closely with similar development efforts worldwide. We have jointly formed the International Virtual Observatory Alliance, bringing together the leaders from all such efforts, and have agreed upon on common roadmap for development and interoperability. Our goal is to build upon the national initiatives to bring about a truly international facility, bringing the world’s foremost astronomical information services and data collections to the fingertips of astronomers, educators, and students everywhere.
Disclaimer
This is a project development site. The software and services available here are prototypes. They are being built in order to evaluate tools and methods and are subject to frequent and unannounced revisions. The NVO project encourages wide use and experimentation of these prototypes, but they may not work with all browsers or user environments. Software and services intended for general use will be clearly identified. We appreciate feedback from the user community.