Onsala Space Observatory/L. Wennerbäck

Onsala's 25-metre radio telescope celebrates 50 years

50 years after its inauguration, the 25-metre radio telescope at Onsala Space Observatory is still producing frontline science.

​With the words ”Per aspera ad astra” county governor Ingvar Lindell closed his speech at the inauguration of the 25-metre telescope at what was then known as Råö Space Observatory on 26 november 1964. “Waxing Lyrical at the Giant Ear in Råö” was the headline in local newspaper Göteborgs Handels- och Sjöfartstidning.

Since then the telescope has spent 50 years studying and seeking answers to the mysteries of the universe. One of its most important discoveries came in 1973, when it was the first telescope in the world to find evidence of the CH molecule in space – a radical which has an important role in the chemistry of the interstellar medium. 

As early as 1968, the telescope took part in the first transatlantic VLBI measurements. VLBI stands for Very Long Baseline Interferometry, a technique in which the same cosmic source is observed simultaneously by a number of radio telescopes spread over the globe. The aim is to achieve much sharper images than the individual telescopes could do on their own.

Making measurements and turning them into images has often been a cumbersome procedure, but a breakthrough came in 2004. 

A new optical fibre network was installed between the radio telescopes and data from three telescopes, among them the Onsala 25-metre, was sent via high-speed network to the data centre in the Netherlands run by the Joint Institute for VLBI in Europe, JIVE. 

By the following day an image of a distant galaxy nucleus as observed by the telescopes was already available. Today, contributing to this type of measurement is the telescope’s most important task.

Michael Lindqvist, michael.lindqvist@chalmers.se, +46 31 772 55 08

Image: Aerial photo of Onsala Space Observatory's 25-metre radio telescope, taken on 25 November 2014 to mark its 50th birthday. 
Credit: Onsala Space Observatory/L. Wennerbäck

Published: Wed 26 Nov 2014. Modified: Wed 26 Nov 2014