Watching the stars for 200 years

The home of the historical McClean Telescope at the South African Astronomical Observatory.

The national heritage site in Observatory – the suburb is named after it – has given generations of astronomers the chance to reach for the stars.

It’s a facility of the National Research Foundation, which operates under the South African Department of Science and Innovation.

It was founded on October 20, 1820 after King George IV authorised the British Admiralty to establish a royal observatory at the Cape of Good Hope to provide accurate star positions that ships could use to navigate the treacherous waters of the Cape.

It was operational until the modern observatory at Sutherland in the Karoo was established in 1972.

Science-engagement astronomer Dr Daniel Cunnama says the light pollution in Cape Town makes it impossible for the observatory base to do any good astronomy these days.

“As the instruments got more sensitive, they required darker and darker skies,” he says.

Sutherland, which is a four-hour drive from Cape Town, offers ideal conditions for astronomy.

“It has high altitude, dark skies with no light pollution and a dry atmosphere.”

There are 18 telescopes in Sutherland, including the Southern African Large Telescope (SALT), the largest single optical telescope in the southern hemisphere and among the largest in the world.

Salt was established in 2005 through partnerships with the UK, America, Poland, Germany, India and New Zealand.

In 2017, it was part of a major global discovery – the first neutron star merger. The merger was first detected as gravitational waves at an American observatory.

“When the two neutron stars merged, they released a massive explosion,” Dr Cunnama says.

Telescopes around the world, including Salt, then performed an optical follow-up for visible confirmation.

Many astronomers alternate between doing research at the SAAO head office in Observatory and visits to the Sutherland base.

A workshop at the head office is where parts are made for the Sutherland telescopes and for the MeerKat radio telescope, which is managed by the SAAO’s sister organisation, the South African Radio Astronomy Observatory (SARAO), and iThemba Labs.

Head of the workshop, Craig Sass, says they have built many instruments over the years and when Salt opened they became more hi-tech.

Dr Cunnama says the 200-year anniversary is a good time to take stock of what they have achieved and what they can still achieve.

“In South Africa, astronomy is one of our treasures. We have our dark skies, which makes for good viewing,” he says, adding that everyone should have “a relationship with the stars”.

Dr Ian Glass, 81, was a senior astronomer at the SAAO before his retirement in 1999, but he still helps with the organisation’s historical work.

Dr Glass says the role of astronomy has changed over the years – the focus on measuring the movement, divisions and brightness of stars has shifted to learning about the origin of the universe and how galaxies are formed.

Dr Glass says throughout his 50 years as an astronomer, he has never tired of it.

“It was like having a hobby that you work at.”

New technological innovations mean that during the Covid-19 pandemic, the astronomers were able to control telescopes in Sutherland remotely from the head office.

“They could open the dome remotely at Sutherland base, point the telescope where they wanted to and make their observations,” says Dr Cunnama.

The SAAO and SARAO, along with their partners, are working on the concept of an Intelligence Observatory in the future, to be based in Sutherland, where all their telescopes will be controlled by artificial intelligence.

“Artificial intelligence will do the observations without the input of an astronomer, though it will be beneficial for astronomers to analyse the data,” says Dr Cunnama.

The SAAO runs public tours twice a month on Saturday evenings, and there are plans for a new visitor centre that will allow for more interaction with the public.

On the tours, visitors can walk through the organisation’s museum to look at all the historical telescopes used by SAAO, including the McClean telescope which was used by the main observatory for over 70 years.

The SAAO has been a national heritage site since December 2018, but on its founding day, on Tuesday October 20, a virtual unveiling of this status – to be attended by government dignitaries – will be live-streamed from 10am on social media.

To find out more about events leading up to the founding day, follow the observatory on Twitter @SAAO, Facebook @SAAOnews and Instagram @SAAO_astro .