Sir

The News Feature on optical telescopes (Nature 408 12 2000 ) reviews the present state of most national telescope operators in Europe and the United States, and identifies some important niches that medium-sized (2–4-m class) telescopes will fill in the future. The story seems to suggest, however, that it is necessary to close most nationally operated 2–4-m-class telescopes in Europe and focus operation on a single site. This is not what has been discussed recently.

What is required is that national telescope operators establish a single European network to coordinate operations of the observatory facilities and the instrumentation of their telescopes. This will allow each site to focus on its particular strengths, while assuring a comprehensive instrumentation complement across the network. The coordination will introduce synergies and allow more efficient operation at each site, which in turn will reduce costs. Without such coordination among national facilities, individual telescopes might no longer achieve the funding to remain competitive and might close prematurely.

At the same time, the network should offer time to European countries that do not operate national observatories or which have no general access to interna-tional observatories such as the European Southern Observatory. Access to other European facilities may foster astronomy programmes in these countries, in the way that Spanish astronomy has benefited from access to installations such as the Institute of Millimetric Radioastronomy in the French Alps, the Isaac Newton Group (ING) on La Palma in the Canary Islands and Calar Alto on mainland Spain.

There has been a very large response to the creation of such a network. During a recent meeting of the Optical and Infrared Coordination Network for Astronomy (OPTICON), members agreed to study a system of instrument coordination and development, and to consider systems to extend telescope access, exchange time between telescopes, and enhance the education and training role of its facilities.

The expected synergies are illustrated by ING and the Calar Alto observatory. With Omega2000, Calar Alto will be operating a near-infrared camera that provides the largest field of view at any telescope in the northern hemisphere. On La Palma, on the other hand, instrumentation efforts focus on adaptive optics and wide-field spectroscopy. Access to both wide-field imaging and wide-field spectroscopy at two different sites offers obvious benefits to the broader European community.

Therefore, medium-sized telescopes can have an exciting future. The undersigned participate as coordinators of two OPTICON working groups which aim to implement the ideas described here.