25 Jun 2018

What does it mean to be a ‘working observatory’?

By Kate Wilkinson

Visit the Altazimuth Pavilion

Over the past year, members of the astronomy team at the Royal Observatory have been busily preparing for the installation of a new suite of telescopes in the 19th Century Altazimuth Pavilion. In between the Peter Harrison Planetarium on one side and separated from the crowd-pulling Flamsteed House and Meridian Courtyard on the other, this small, unassuming building has just been restored and now houses a suite of four state-of-the-art telescopes (and one 1.6inch aperture guiding telescope), collectively called AMAT: the Annie Maunder Astrographic Telescope. The building’s capacity for only 12 people means the opportunity to see these new instruments is somewhat limited. However, the vision for these telescopes lies online: captivating images of the Universe will be able to reach a global audience, bringing astronomy at Greenwich to the world. 

Astronomy now

The telescopes that we’re going to be opening this summer take the Royal Observatory back to being a ‘working observatory’ in the sense that we can do research-grade observations, and contribute once again to advancing human knowledge of the universe. Though our astronomers are keen to stress the telescopes’ main purpose for public engagement, the potential for research and discovery has returned to Greenwich.

The reason this is happening now is that modern equipment has allowed us to bypass a lot of the disadvantages that drove astronomy away from Greenwich in the middle of the twentieth century. Telescope technology has advanced dramatically in the past decade; for example, there are filters that can block out the colours from the sodium lamps used in street lighting. Compared with the last telescopes at Greenwich considered cutting-edge in their time, the AMAT should be able to replicate nearly all of the functions of pretty much all the historic telescopes that we’ve had on site over those hundreds of years.

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Installation timelapse by Tom Kerss

Astronomy then

What does it mean to be a ‘working observatory’? And why did Greenwich stop being one? When the Observatory was commissioned in 1675 by Charles II, the first Astronomer Royal John Flamsteed needed somewhere away from the smog and pollution of London, and Greenwich was just a small town at the time, with a nice hill. A perfect vantage point on which to build an observatory. But by the 19th Century, London had absorbed Greenwich, meaning the smoke and pollution were again a problem, and by the 20th Century, light pollution from the street lights meant that whatever advantage Greenwich had for observing no longer existed.

The Dallmeyer photoheliograph, used by Annie Russell to measure sunspots.

After the Second World War, Greenwich’s important role in navigation and timekeeping was transported to the safer Sussex countryside, and since then, the Royal Observatory’s role as a research body never made its way back. Its buildings were given to the National Maritime Museum and it became a museum for the history of astronomy, navigation and time-keeping. Over the years, many of the historic telescopes returned and the Observatory has become a national centre of excellence for astronomy education and outreach. Many of the Victorian telescopes still work, and stargazing for the public has always been part of the programme. This crucial function is about to be radically transformed.

Building a dream

Astronomers Brendan Owens and Tom Kerss masterminded the AMAT operation. New telescopes at the Royal Observatory had been a long-term dream, but the restoration of the Altazimuth Pavilion finally brought the budget and scope to realise it. In 2017, a members and patrons appeal successfully raised the funds and Tom found himself in a surreal position. 'I thought: what would my dream observatory be? This is it,' he says. Having overseen other observatory installs in his career, Tom brought the experience needed to make good decisions with the money. Between them, the Royal Observatory’s astronomy team has a vast and varied experience using instruments including the Hubble Space Telescope, the Isaac Newton telescope, the William Herschel telescope, and other big telescopes in places like Hawaii and Chile. 

What would my dream observatory be? This is it

Tom says we shouldn’t underestimate the importance to astronomy of smaller ground-based observatories, pointing to the 2017 exoplanet discovery made by the 60cm TRAPPIST telescope operated by the University of Liège in Belgium. Ground-based observatories can be more flexible than space telescopes which are carefully positioned to look at one part of the sky. In modern astronomy, there aren’t enough powerful telescopes around the world to tackle all of the interesting questions at the same time, so there’s great competition to use them. The astronomers here hope that students and scientists will be able to use the AMAT for their own research.

Astronomer Brendan Owens prepares the new Annie Maunder Astrographic Telescope at the Royal Observatory Greenwich

The spirit of Annie Maunder

Ground-breaking discoveries are an exciting prospect, but they’re more of a bonus than the main point of this project. ‘Even if we get no research results in five years, I would still consider this to be a success as long as we reach and inspire people,’ Tom says. AMAT will continue the Observatory’s tradition as an outreach institution and bring the wonders of astronomy to generations to come. Due to the technological advances, urban observatories are on the rise, and a growing proportion of the world’s population lives in cities. 'If we can’t take back the night sky we’re lost,' Tom says.

Annie Scott Dill Maunder (née Russell) by Lafayette 1931 © National Portrait Gallery, London AMAT’s dual role is aptly matched to its name-sake. Annie Maunder explored the night sky and its phenomena as an astronomer, astrophotographer and science communicator in Greenwich during the 1890s and early 20th Century. She was hired as a human computer at the Royal Observatory in 1891, and though, as a government employee, she was required to give up her position when she married fellow Greenwich astronomer Edward Walter Maunder, she continued to participate in science, publishing books to inform and inspire others and returning to work at the Observatory during the First World War. She was also one of the first women to be elected as a Fellow of the Royal Astronomical Society in 1916. By the end of her life she had gained an international reputation, particularly for her work examining the Sun during eclipses for which she designed her own specialised cameras. 

The ‘astrographic’ part of the AMAT refers to the telescope’s design to be used with digital cameras. Camera technology and the birth of photography brought about advances in both astronomy at large, and the participation of women in the field. Compare the influence of photography in the 19th and 20th centuries to the role of Big Data now: then as now, you are dealing with huge amounts of data in all sorts of areas of science, and then the question is what do you do with it? Where do you find the human hours to look at the data?

Nobody could claim that women couldn’t be top-notch astronomers – because they were already doing it

With the growing need for extra ‘man power’ to analyse and keep track of all the photographs of the night sky, observatories like those in Harvard and Greenwich brought in not man power but woman power. Intelligent women were graduating from the new women’s colleges and could be paid less than their male counterparts. Although that was exploitative by modern standards, it was also a foot in the door that enabled many women to get paid jobs in astronomy for the first time. After the early 20th Century, nobody could claim that women couldn’t be top-notch astronomers – because they were already doing it.

Annie Maunder was one of these women. She and her colleagues were part of the photographic revolution in science, using the technology to study the stars in new and powerful ways. Since the Observatory’s photographic department was founded in 1873, astronomers in Greenwich used the camera to capture the Transit of Venus in 1874, to discover the eighth moon of Jupiter, and even to prove Albert Einstein’s General Theory of Relativity for the first time by measuring the bending of light during a total solar eclipse. 

Find out more about Annie Maunder

First Light

After months of fundraising and planning, the AMAT arrived in Greenwich. Brendan and Tom spent long nights in the Altazimuth Pavilion setting up the instruments. It was an exciting, though exhausting time. 

When a new telescope is launched, the first images it captures are called its ‘first light’. These are not generally the highest quality, but they are meaningful - especially to the telescope’s operators. Like with most major telescopes, the real 'first light' images came through as part of the calibration process, and therefore look more technical than aesthetically pleasing.

AMAT calibration plates, stars

You sometimes forget when you’re doing astronomy that you’re looking at another world.

Brendan says the Airy Crater on the Moon was one of the targets for AMAT’s first light. As Astronomer Royal from 1835 until 1881, George Biddell Airy made large expansions to the Observatory, allowing its research to branch out into new fields, including spectroscopy and photography. The astronomers have also used AMAT to photograph both the Sun and the Moon at large; solar imaging reflects Annie Maunder's specialty and the Altazimuth Pavilion was originally built to look at the Moon.

Tom describes the moment when AMAT’s first images came through: 'It was quite stirring... Everyone was quietly watching the screen. You sometimes forget when you’re doing astronomy that you’re looking at another world.'

The road to AMAT’s first light took time and planning, and the instrument is now up and running. However, this moment is really just the beginning: the project has provided the Observatory team with yet more projects, opportunities, and time inside the Altazimuth Pavilion’s domed roof.

Watch this space for more images of other worlds to come.

The Moon | credit: AMAT

Greenwich and astrophotography

Louise Devoy, Curator of the Royal Observatory, has been researching the ties between astrophotography and Greenwich over the decades. These are some key milestones in Greenwich’s use of astrophotography:

By 1839 practical photography was born and since its inception, the technology was used in astronomy. It was initially regarded as a time-saving tool to help reduce labour costs.

1873: The Royal Observatory’s Photographic Department was founded.

1874: The Transit of Venus of 1874 was the first transit to be observed photographically as the previous one has taken place over a century earlier in 1769. Greenwich astronomers travelled to different areas outside Europe where the transit was visible to photograph the event and compare data.

The Transit of Venus 1874 - historic photograph A square glass plate negative of Transit of Venus taken at Honolulu in 1874 with one exposure of the planet Venus crossing the Sun's limb. AST1082

1898: Annie Russell Maunder photographed the Sun and captured the tendrils of its outer atmosphere, the corona, as seen during an eclipse.

1900: Some of Observatory staff got together to create a Camera Club to pursue photography for their own leisure, as well as use as a work tool.

1908: Greenwich astronomer JP Melotte found a new, eighth moon of Jupiter while studying a photographic plate (the Moon appears as a tiny faint dot, which has been circled and marked with the numeral ‘VIII’).

1919: Two groups of Royal Observatory astronomers, one based on the northern coast of Brazil and the other just off the west coast of Africa, used photography to capture the bending of starlight by the gravitational field of the Sun during a total solar eclipse. This supported Einstein’s Theory of General Relativity by becoming the first to observe and measure the effect Einstein had postulated. The deflection of starlight on the glass plate was tiny – just a fraction of a millimetre – but photography made it possible.

Image of solar eclipse in 1919

2008 – The Astronomy Photographer of the Year competition was launched.

2018 - The Annie Maunder Astrographic Telescope is installed in the Altazimuth Pavilion.

The Sun | credit: AMAT