Windows to the Stars

For seven decades, the world worked to map the heavens – a massive endeavour that ran from the 19th century to the era of manned space flight, taking in two world wars and vast social change. In this article, we explore Australia’s role in the project and the lives of those who measured the stars: the “lost women” of Australian astronomy.

This activity would be suited to inspire students in years 4 to 10 who are studying Earth and Space or Chemical Sciences to pursue a career in STEM, even when facing obstacles and challenges. The articles, from Cosmos magazine issue 86, are split into two shorter pieces written by Ivy Shih and Dr Toner Stevenson.

Word Count: approx. 3900 (total)

Circa 1900, an astrographic measurer uses the “Repsold” micrometer – measuring machine – at Melbourne Observatory to catalogue the stars of the southern hemisphere. Credit: Collection Museum Victoria

To an untrained eye, the glass plate resembles a dirty tile covered with tiny black spots – as if an ink-filled paintbrush had been gently flicked across its surface. But in fact the plate is a piece of the night sky – the glass-plate negative from a photograph taken over a century ago. Each black speck – shown on these pages –is a single star.

There are thousands of such plates – the precious residue of one of the most ambitious international astronomy projects undertaken in the 19th century. The goal was to use photography to map the entire sky and create a complete record of the stars, known as the Astrographic Catalogue (AC), and a separate project of printed images called the Carte du Ciel.

Originally estimated to take only a few years, the project would span more than seven decades in Australia. Behind the scenes were female “human computers” who diligently measured and calculated the position of tens of thousands of stars, whose work has remained mostly unnamed and unrecognised for decades.

Glass plate negative from a photograph of the night sky taken over a century ago. Each black speck is a single star. The goal of taking these images was to map the entire sky and create a complete record of the stars. Credit: Collection, Museum Victoria.

Toner Stevenson was manager of Sydney Observatory in 2004 when she first saw the glass plates with observatory curator Nick Lomb. Each was 160 mm2, with a curved corner at the bottom left. She’d been reading about the AC for her doctoral thesis and had come across a sentence saying that the star measurements were why the project took so long.

The search for an answer led her to Macquarie University’s library and a basement lined with shelves stocked with thousands of cardboard boxes – each containing up to a dozen glass plates in paper covers, where they had rested for 20 years.

When Sydney Observatory stopped being a research station, Macquarie University astronomer Alan Vaughan volunteered to find a place to store the thousands of plates in its collection, and the University signed an agreement with the Museum of Applied Arts and Sciences, which currently operates Sydney’s Powerhouse Museum and Museums Discovery Centre, as well as the Sydney Observatory.

Each glass plate was wrapped in a paper cover with notes and observations; Vaughan was their caretaker from 1986. He recalls finding a 1910 cover with the notation “Halley’s Comet”. The glass plate inside had an image of the comet itself – a dark brushstroke across the surface rendered as it streaked across the sky.

The collection included the original logbooks and catalogues, which preserved all the data of exposure – including date, time, weather, observer, length of exposure, the relative ascension and declination (coordinates) and the plate number.

“I thought: This is an incredible story because this is the sky captured during a single epoch, because most of the photographs were taken over 20 years from 1895 to 1915,” says Stevenson, who now manages the University of Sydney’s School of Philosophical and Historical Inquiry. “So it was capturing something we could never capture again.”

The Great Star Catalogue

At Paris Observatory in 1887 a remarkable meeting of astronomers from around the world produced a startling idea – to create a map of the skies using the latest photography and measuring techniques. It would capture the position of the stars in both northern and southern hemispheres.

The task of compiling the work would fall to 18 observatories around the world. The sky was divided into zones, allocated to different observatories. In Australia, observatories in Melbourne and Sydney were the first to take part. Adelaide came on board shortly after to assist Melbourne; Perth joined the effort in 1900, taking over the zones originally assigned to Rio de Janeiro Observatory. Together the Australian contingent would go on to map 43% of the southern hemisphere – one of the richest concentrations of stars because the Milky Way galaxy crossed right through it – and 17% of all the stars recorded.

The AC aimed to record the position of all the stars, and the Carte sought to be one of the most detailed photographic charts of the heavens. Each would require separate glass plates. The plan was to make photographic charts of all stars down to the 14th magnitude (some 40 million stars) and catalogues of the positions of stars down to the 11th magnitude (two to three million), based on accurate measurement of the photographs.

Coated with a special dry gelatine emulsion, the stellar photography plates were first exposed to a réseau plate – the same size as the photographic plate, but coated in silver and ruled into a grid of fine lines five centimetres apart. The réseau plate was placed in direct contact with the photographic plate and exposed for four to five minutes to imprint the réseau grid on the emulsion. The result was a photographic slide traversed by a grid of very fine lines – indispensable as reference marks in determining the placement of the stars. The plates were then ready for star photographs.

Male astronomers took the photographs using special “astrographic telescopes”. Every four-to-six-minute exposure was arranged so that a plate would show a number of standard stars, from which the rest of the stars on the plate – varying from 300 to 1000 – could be measured. In Australia, most of the photographs were taken by 1915; some were later retaken. Each contained hundreds, if not thousands, of stars.

Ensuring precise measurements was an intricate process. Originally the plates were to be measured at a central facility in Paris, but a change of plans saw the work transferred to individual observatories; Melbourne and Sydney shared a measuring bureau located in Melbourne.

The women who observed, catalogued and calculated the star positions on the AC had outstanding mathematical ability, with the analytical skill to measure and calculate the stars’ positions. They worked on purpose-built measuring machines called micrometers and used standard astrometry reduction formulas to determine the true star co-ordinates.

They worked in pairs, exchanging roles to measure each star on each photographic plate twice – once on the front face and again when the slide was turned 180 degrees. The photographic plate was placed in a micrometer and the star’s X and Y co-ordinates were measured and calculated. The measurer on the micrometer would read out the data, which was entered into logbooks by the second measurer. Afterwards the mean of the two measurements was calculated and also entered into the logbook.

Co-ordinate measurements were compared between measurers in an effort to eliminate human error. Given that the plates overlapped, each star could be measured three or four times. Given front, reverse and overlap measurements, each glass plate was handled multiple times. According to contemporary reports in the project’s early years, on average 170 stars could be measured in an hour.

Using micrometers (left), measurers catalogued up to 1000 stars on each glass plate. The southern hemisphere’s circumpolar star chart (right) was largely created through the observatories in Sydney (shown in blue) and Melbourne (green). Credit: Collection: Museum of Applied Arts and Sciences. Photographer Chris Brothers, State Records Authority, New South Wales.

The Worth of Stellar History

When the Sydney AC’s final volume was published in 1964, Australia’s involvement officially came to an end. The global endeavour to chart the heavens had lasted almost eight decades. Stevenson estimates that over that time Australia’s astronomers charted and measured the positions of more than 1.5 million stars. They photographed 142,021 glass plates and published over 50 catalogue volumes. Stevenson’s research indicates that Sydney and Melbourne completed their Carte photography; Perth exposed only 100 plates before abandoning the project after 1903.

The global astronomy and scientific community managed the immensity of the AC and Carte projects through the opening and closing of observatories and multiple funding and budget cuts. Work had waxed and waned but seemed to be a constant through a world changing around it. The project had continued through the Great Depression and two world wars. Even when Melbourne Observatory ceased research in 1945 and closed in 1948, Sydney Observatory decided to complete the unfinished measurements and take the projects through to completion.

Astronomy had also moved on. In the 1940s, Ruby Payne-Scott’s work in radio physics and radio astronomy cemented her as an Australian pioneer – she is among the first female radio astronomers. In 1961, the Parkes radio telescope was opened. Just five years after Australia’s work on the AC finished, Apollo 11 landed on the moon.

Now it only takes months to image the night sky. The Cerro Pachón ridge in north-central Chile will soon host the new 8.4-metre Large Synoptic Survey Telescope at the newly named Vera C Rubin Observatory, which is capable of surveying the entire southern hemisphere sky in just three days. The goal is to take 800 separate images of each region of the night sky over 10 years.

Given this, it seems easy to view the AC and Carte as historical remnants of humanity’s ambition and attempt to have some degree of mastery over the heavens. But the glass plates and catalogue have a legacy that’s still playing a part in modern astronomy.

Each glass plate’s smattering of black spots is the light of stars past – a unique window to the state of the night sky up to a century ago. The plates are effectively time capsules that allow astronomers to study the evolution of galaxies. Space is a constant roil of activity and motion of celestial bodies, dying, colliding and being born. Within the plate images are data that opens up new possibilities in astronomical research.

Filed in numbered bespoke boxes, the glass plates and their attendant logbooks are held at the Powerhouse Museum, Sydney. Only 650 plates have been digitised. Credit: Collection: Museum of Applied Arts and Sciences. Photographer Chris Brothers

This is because of the speed at which light travels. It takes 1.25 seconds for moonlight to reach Earth. The Sun’s light takes more than eight minutes. Whenever we peer through a telescope at Proxima Centauri, Earth’s closest star other than the Sun, we’re looking at starlight that began its journey to Earth 4½ years ago.

As Alan Vaughan’s research student 20 years ago, Lesa Moore painstakingly created a digital catalogue of the glass plates at Macquarie University. She spent months going through the plates, transcribing what they contained.

“The idea [was] to get… the variability and the movement in the stars so we can understand how little sections of space are evolving,” says Moore, who is now web editor at the Astronomical Society of New South Wales.

Keen to see the potential data locked in the glass plates, in 2006 Vaughan used a custom-built suitcase lined with rubber pillows to transport 650 plates to Cambridge University, where the Automatic Plate Measuring Machine at the National Astronomy Facility was capable of scanning each image in layers, thus ensuring every star was included.

When the images came back from Cambridge, Vaughan and Moore assessed the quality of each plate and, using software, extrapolated the stars’ positions and modern co-ordinates to determine how much they had moved in the time since the photograph was taken.

“To get a historic baseline and see things change in time is very difficult in astronomy,” Moore says. “We can’t wait around and see a star go supernova. We have to get all of the information from what we can see today and however far back our records go. So any kind of historic record, even sketches that date back before photography, are useful in understanding how celestial objects and systems evolve.”

The entire AC collection is now housed at the Powerhouse Museum. When Moore was cataloguing the fragile glass plates, she found that the years hadn’t been kind to them. Some were broken; the silver coating on some had oxidised to a solid black; mould had started to take hold on others.

On one glass plate, Moore could make out, among the smattering of dots, the curve of something that didn’t resemble any celestial body. Its identity remained a mystery until the plate was scanned at Cambridge. It was a partial fingerprint – a mark among the stars to remind us of those who captured and catalogued the sky.

This article was written by Ivy Shih, former medical researcher and science writer based in Sydney for Cosmos Magazine Issue 86.

Veiled beneath the Astrographic Catalogue’s canopy of stars was a corps of female “computers”, who measured and recorded the stars’ positions – and much more besides.

Perched at two sturdy tables are four young women working in pairs. One, an observer, is concentrating deeply, looking down into a microscope at stars on a fragile glass-plate negative. The window shines onto a mirror that reflects light to illuminate the stars on the photograph.

Mary Allen and Ethel Wilcocks measuring astrographic plates at Sydney Observatory in 1941. The “computers” worked in pairs, one reading measurements off the micrometer and the other recording them in a logbook. Credit: Collection: Museum of Applied Arts and Sciences. Photographer Nitsa Yioupros

The observer has positioned the glass plate so she can see a single square of the réseau grid lines. She turns tiny screws to move the microscope up, down or across and focusses the eyepiece on a single star-speck within the grid, making sure the réseau lines align with a square – made from taut spider-web silk – visible through the eyepiece.

Guided by a glass reticle with a graduated X-Y axis scale, she reads out the co-ordinates for the star’s position to her partner, who writes them down in a neatly ruled logbook with a sharpened pencil. Then she compares the size of the star with a slide of “standard star” brightness dots, which she passes in front of the eyepiece using tweezers.

Around the women are dark timber bookshelves filled with logbooks, manuscripts ready for the printer, and hundreds of boxes containing thousands of photographic glass-plate negatives taken at Melbourne Observatory and by their own Sydney Observatory astronomers.

It’s 1948. The observer – Winsome Bellamy – and her three colleagues have been employed to finish the Astrographic Catalogue, which Sydney and Melbourne observatories had begun back in 1887. The machines they are using were designed in 1904 and their methods are the same as used decades earlier.

When I interviewed Bellamy years later, she recalled that she found the work routine: “We had turns about to use the machine, because your eyes became very tired with looking through the micrometer. The other person would sit and write the figures down. We did about half an hour, or perhaps longer on the machine. And then we would swap places and the other one would have a turn.

Physicist Ruby Payne-Scott (left, in 1948) was one of the global pioneers of radio astronomy. In the late 1940s, she worked with Alec Little, centre, to design and build equipment to map solar radio emission strength. Like the female AC computers, Payne-Scott is better known now than during her lifetime.

“The four of us were working beside each other with the two different machines. But we talked all the time, while we were doing it, and swapped gossip and jokes. And we had a great time apart from work.”

Bellamy was among the more than 70 women employed to measure, log and calculate the position of stars for the AC at Adelaide, Sydney, Melbourne and Perth observatories. They were called “computers”, “star measurers” and “clerical assistants”.

But they were far more than an anonymous group of women who measured. They were fascinating individuals who produced new knowledge about stars, particularly those in the southern hemisphere, and they had agency within the observatories that has not previously been recognised.

They have in common their contribution to astronomy – and the fact that their work has been almost forgotten.

Women had worked in astronomy as daughters, wives and sisters of astronomers for centuries, but the first Australian woman paid a regular wage for her work was Mary Emma Greayer (1861-1910), who was employed in 1890 on a temporary clerical contract at Adelaide Observatory.

Greayer was educated to the equivalent of today’s School Certificate. Her sister married William Cooke, an assistant astronomer at Adelaide Observatory, to which Greayer became a regular visitor. It appears she was genuinely interested. Charles Todd, the Government Astronomer, must have noticed her aptitude, because she left teaching to start work as one of two observatory computers.

Mary Emma Greayer (pictured c1895 with Adelaide Observatory staff Charles Todd and William Ernest Cooke) commenced employment as a computer. She went on to observe reference stars – coordinates that formed the foundation for measuring the position of other stars. She had to resign in 1899 when she married.

The attendance books reveal that she did a lot more than computations while working from 7:30 pm to 10 pm, two or three evenings a week. And when I found the observation logbooks, I was surprised to see her initials regularly noted as “observer”; she was determining star positions, looking through the large transit telescope and reading out the location and magnitude of stars, sometimes to Cooke and sometimes to assistant astronomer Richard Griffiths, alternating with them to record their observations.

Greayer was, in all ways, doing the work of an astronomer, and she was one of the first women to be elected to the South Australian Astronomical Society, where she presented papers. Although she didn’t have access to a university education, she clearly had an aptitude and passion.

Other passions were developing during those long stellar nights, however, and in 1899 she married Griffiths and had to resign – as married women were required to do. Todd lamented her departure and wrote to other government astronomers comparing her to the renowned German comet discoverer Caroline Herschel.

Melbourne Observatory was the first Australian institution to establish an AC measuring bureau – imitating what the Paris Observatory established in 1890 – by employing women as computers and measurers. In Australia in the early 20th century, women were generally paid 54-64% of a male salary when the work was specifically identified as “women’s work”. This made women attractive as a cheap source of labour.

In 1902, an anonymous journalist writing about the Melbourne Observatory women in “The Women’s Corner” section of the Brisbane Courier said: “Their hours are from 9 am to 5 pm on weekdays and to noon on Saturdays, an hour being allowed for lunch. Their salary is £40 a year. (The editor has only one remark… no man would undertake it at more than double the amount).”

Greayer was doing the work of an astronomer, and was one of the first women to be elected to the SA Astronomical Society, where she presented papers

Charlotte Emily Fforde Peel (1877-1974) was selected as an “astrographic computer” in 1898 due to her outstanding mathematical ability – demonstrated in the exam set by the observatory. She had been a teacher and was transferred from the Education Department at the age of 21 as the most promising of the first six women to work on AC star measurement.

The women were trained for six months or longer and Peel became their leader, checking the accuracy of their measurements, timingeach woman’s efficiency against it and calibrating the measuring machines. It was estimated that 80 stars per hour could be measured using the high-cost, finely tooled machines made by Repsold, from Hamburg, Germany, and pace as well as accuracy was essential.

Peel was performing the same duties as Dorothea Klumpke, the first woman with an advanced degree in astronomy, who was the Director of Paris Observatory’s Bureau des Measures from 1890.

Melbourne Observatory, which had been a male-dominated building, had to become more feminised. The women’s spaces were separated from the men’s; there was a fear that the men would be distracted. Isolation had its benefits, and the women often formed strong friendships with their measuring partners and socialised after work. Logistics, such as a lack of outhouses (toilets) had to be solved. New conveniences were built in 1903 – but not connected until years later. This understandably caused angst.

Peel was officially gazetted as “assistant astronomical computer” in 1900. She was the first woman to hold a permanent position in astronomy in Australia. She worked on the AC for 20 years and only left when she married Robert Sangster, the observatory librarian, in 1919.

When Perth Observatory joined the AC program and established its “measuring bureau”, Prudence Valentine Williams (1891–1968) – already identified as an outstanding student by winning a gold medal in her leaving exam – was one of two women employed as junior clerks in 1906. She was 16, but highly intelligent and capable, and soon became the leader of a growing number of employed women.

Williams was passionate about astronomy and was elected to the Astronomical Society of Western Australia. Her work ethic and diligence were extraordinary, but even more remarkable are her letters to the observatory director HB Curlewis, where she championed the rights of the women.

In 1913, through her letters, and with the support of the Government Astronomer, Williams managed to gain a stepped increase in wages for the women, which effectively meant their wages doubled within a few years. She also successfully argued for her level of responsibility to be acknowledged financially and by title as Librarian and Astrographic Supervisor. Her demands that the women become permanent public servants was never granted, however.

Photographed in 1949 by their 21-year-old colleague Winsome Bellamy, star measurers (above, from left) Verlie Maurice, Renee Day, Patricia Lawler, Jean Campbell and Margaret Colville enjoy lunch in Observatory Park, Sydney.

In 1914 a male astronomer reported the women for spending too much time talking. Williams wrote to Curlewis that “…Mr Nossiter must have a vivid imagination when he states that some days we talk almost incessantly; he is evidently judging us by himself, as for about two months… he and Mr Whitby talked almost incessantly”.

Williams explained that the four women had twice measured, calculated and prepared for publication 21,221 stars within a six-month period, ending pithily: “…I am afraid he cannot show a corresponding amount of work for the same period.” Curlewis supported the women.

Williams and the other women were identifying not only star positions and brightness, but also unusual images of double stars and anything that seemed out of the ordinary. Their double-star observations were published by an astronomer without recognition of their work in identifying and measuring the stars.

Williams left the observatory in 1918 to care for her brother, who was returning from the Great War. She is not mentioned again in astronomy.

When Melbourne Observatory closed in 1948, Sydney Observatory undertook the completion of the AC and a new group of women, including Winsome Bellamy, then 20, were employed. Like the women who’d preceded them, they had no higher education in astronomy.

Bellamy became dedicated to the project, bringing in spiders from home so their web-silk could be used for the cross hairs in the measuring machines.

“I finished my training as a children’s nurse,” says Bellamy. “And my mother got very sick and I had to be home decent hours. We had three small children at home… So, I got a job with the public service. They didn’t tell me what I’d be doing…. I had not experienced anything to do with astronomy before and I found it boring.”

Although she was employed temporarily, Bellamy stayed on for 20 years and became dedicated to the project, bringing in spiders from home so their web-silk could be used for the cross hairs in the measuring machines and other instruments. She enjoyed the company of the different women who came and went every few years, mainly leaving because they married. Only single women could be employed in most areas of the public service.

When Sydney Observatory set up its measuring bureau, a new wing was added and the women had their own space and library. Bellamy was featured in photographs for the newspaper when a new measuring machine was purchased; she was herself an avid photographer of the social life at the observatory.

During lunchbreaks the women played badminton or, when it rained, fixed a net onto a large table to play table tennis. The young astrographic measurers enjoyed their lunches overlooking Observatory Hill. Every now and then they dressed up to attend one the many weddings that would signal the end of working life for one of their colleagues.

Through the AC, colonial state government astronomers were connected with new methods of science via international co-operation and collaboration. It was at the forefront of what we now call “big data” – but it’s not a well-known project.

Sydney Observatory director Harley Wood wrote about the AC in his 1964 doctoral thesis: “It must be understood that this work is essentially that of a team. The photographs on which the catalogue is based were taken mainly before my arrival… The measurement of the plates was performed mainly by assistants without scientific training. Throughout the years 19 assistants have been engaged with me in this work, with not more than four being employed at any one time.”

Winsome Bellamy – shown below at the micrometer in 1954 – spent 20 years completing measurements and calculations for the Astographic Catalogue.

Wood acknowledged Bellamy’s work, and that of her close co-worker, Margaret Colville, in the publication of the catalogue of stars.

The women were essential to that team. With the exception of Charlotte Peel and the acknowledgement she received for comet observation, even when the women discovered unusual phenomena such as double stars, they were obscured from recognition in scientific papers.

Dorothea Klumpke described the work of producing astronomical catalogues as “astronomical labour”. She acknowledged that it was tedious, but “truly scientific” in its nature.

According to Klumpke, women have: “qualities prerequisite for producing lasting results – concentration and enthusiasm, powerful levers that move worlds. Ours is a work of the night and day! … astronomical science now becomes universal! She knows no boundaries, no rank, no sex, no age!”

This article was written by Dr Toner Stevenson, manager of Sydney University’s School of Philosophical and Historical Inquiry and manager of Sydney Observatory from 2003 to 2015 for Cosmos Magazine Issue 86.

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