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50 years of searching the skies with INT

Fifty years on from the inauguration of the Isaac Newton Telescope (INT), this international science facility remains a powerful research infrastructure which continues to provide answers to some of the most pressing questions in astronomy.

Tomorrow (1 December) marks five decades since Queen Elizabeth II inaugurated the telescope, which now operates on La Palma. In the 50 years since the facility first opened it has undergone continued improvement and development – being fitted with the latest instruments and technology to ensure the best view of stars, galaxies and the universe.

The INT is operated by the Isaac Newton Group (ING), which is co-managed by the UK’s Science and Technology Facilities Council (STFC).

Dr Marc Barcells, director of the ING, said: “The history of the INT shows the remarkable vision and determination of UK astronomy, resulting in 50 years of discoveries at the cutting edge of research, initially from Herstmonceux in the UK, and for the last three decades as part of the UK/NL/Spanish collaboration on La Palma. Upcoming new instrumentation will ensure that the INT remains scientifically productive for many years to come.”

Isaac Newton Telescope

The Isaac Newton Telescope (Credit: Max Alexander)

The history of the INT

As World War Two drew to a close and the UK's research priorities were being defined for the post-war years, it became evident that building a large astronomical telescope needed to  be high on the list if UK astronomers were to compete with their American counterparts.  The project to build the new telescope was effectively launched in 1946, but two decades were to pass before it was ready, partly because of the many technical challenges posed.

In August 1967, the 2.5m Isaac Newton Telescope, named to celebrate the tercentenary of Newton's birth, saw first light at Herstmonceux on the south coast of England.  It was inaugurated by Her Majesty the Queen on 1st December 1967.

With the rise of radio and space astronomy, and the discovery of quasars, the INT had arrived at an opportune time and it delivered many science highlights at Herstmonceux.

Soon, however, it became apparent that the telescope's full potential was not being met in the less-than-ideal observing conditions in the UK, with its changeable weather and worsening light pollution from nearby population centres.

Fortunately, an opportunity soon opened up for the telescope to be moved to La Palma in the Canary Islands, under whose clear dark skies a new international observatory was being created.  The INT saw first light on La Palma in 1984.

50 years at the forefront of research

The INT functions as a world-class research facility and a training institution for new astronomers who will design and use the next generation of giant telescopes.

Many of today’s senior astronomy professors at UK universities carried out much of their training as optical observers at the INT in the 1980s, when it had just re-opened at its new location on La Palma. That experience was deemed so useful that in the 1990s universities asked the ING to establish a resident student programme.

The ING now hosts up to six students per year, who spend 12 months as INT support astronomers.

Over the years, the INT has hosted various imaging cameras and spectrographs. Today, it has just one of each: a wide-field camera placed at the prime focus of the telescope, and an Intermediate Dispersion Spectrograph (IDS), an old instrument which still performs well thanks to new detectors and new electronics. Both imagers and spectrographs have led to remarkable discoveries.

For instance, in 1992 the IDS was used in a long campaign that led to the conclusion that the binary star V404 Cygni harbours a black hole – the first stellar-mass black hole confirmed in our galaxy, and a milestone in black-hole research.

Using the wide-field camera on the INT, an international team of astronomers also made the first complete maps of the northern Milky Way in the red light of hydrogen, and also in ultraviolet light.

INT dome and building

The INT dome and building (Credit: Rainer Girnstein)

The future is bright

In the coming years, the INT will be modernised to allow remote or robotic observations, and will focus on the detection and study of extra-solar planets. A team led by Cambridge University is building an ultra-stable, high-resolution spectrograph capable of measuring velocities with accuracies better than 1 metre per second.

The UK celebration event for the anniversary is being held at the Observatory Science Centre in Hertsmonceux, with a series of talks from former Royal Greenwich Observatory astronomers and Dr Barcells.


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