Virtual observatories and access to radio interferometry data

Radio interferometry produces visibility data which can be processed flexibly to achieve higher resolution or better surface brightness sensitivity. These results are now within the reach of any astronomer as radio archives appear on-line and pipelines and other user-friendly data reduction tools become common. All raw VLA data are now available by ftp via a web form offering many search parameters. Images from the MERLIN archive, the NVSS, SUMSS and other surveys and many radio catalogues are already published electronically directly and via CDS. However a typical 1024 × 1024-pixel image covers less than one percent of the typical potential field of view. The ideal solution is to store calibrated visibility data and produce images or other products on demand to user specifications. Prototypes have been developed to do this via web interfaces (not requiring any specialised radio astronomy knowledge) for the MERLIN and ATCA archives. © Springer 2007.