The Women "Computers" of Mount Wilson Observatory

Carnegie Science's Mount Wilson Observatory is renowned for groundbreaking discoveries that reshaped our understanding of the cosmos. Yet, amidst the towering telescopes and the celebrated names of male astronomers like George Ellery Hale and Edwin Hubble, there exists a lesser known, but equally important narrative—that of the women of Mount Wilson’s Computing Division, who worked meticulously reducing and analyzing data from astronomical glass plates.

When Carnegie Science established Mount Wilson Observatory in the San Gabriel Mountains overlooking  Pasadena in 1904, the field of astronomy was undergoing a transformative period of growth. Advances in technology, particularly the development of large telescopes and the use of photography, revolutionized observational astronomy. And they produced mountains of astronomical data that required skilled personnel to process.

These tasks required precise attention to detail. They came to be assigned primarily to women, often referred to as “computers,” who could be paid less than men and who were thought to possess particular skills, like patience, that made them well-suited to the repetitive work. At Mount Wilson Observatory, and other observatories at the time, professional roles were gendered. Male astronomers would observe overnight in the telescope domes, taking photographs of the sky that would then be reduced by the women of the Computing Division, working at the observatory offices in Pasadena. Men also synthesized and published the ultimate research findings.

The women of Mount Wilson’s Computing Division, many of whom hailed from then-newly established women’s colleges, were considered part of the Observatory's scientific, or investigatory staff, not office staff, and contributed to the astronomical breakthroughs that were happening at Carnegie.

They worked six days a week measuring the positions and magnitudes of stars, calculating the position and intensity of spectral lines, and counting and measuring sunspots. They also socialized together and had some opportunities for professional development.  A delightful photo album kept by computer Phoebe Waterman Hass shows women of the division hiking up Mount Wilson and attending the fourth conference of the International Union for Cooperation in Solar Research hosted on the mountain in 1910.

Yet, these positions were low-paying and low-status, and the women had almost no opportunity for promotion or freedom to pursue independent research. Women were excluded from observing on Mount Wilson, and the excuse that there was no suitable place for a woman to stay overnight was used into the middle of the century.

Waterman Haas, who worked in the Computing Division from 1909-1911, expressed frustrations that must have been shared by many of her colleagues when she wrote “But oh, I do want so much a position as astronomer, part of my work with the instruments and part with the reduction of my plates, as men here have.” Finding she had gone as far as she could at Mount Wilson, Waterman Haas left the observatory to pursue a Ph.D. in astronomy at Berkeley.

Some women of the Computing Division managed to carve out additional space for themselves. Louise Ware, Mount Wilson Observatory’s first woman “computer,” recruited to the Observatory by founder George Ellery Hale in 1907, co-authored five papers with solar astronomer Charles St. John on topics in solar astrophysics. Ruth E. Smith co-authored a paper on sunspot prominence with visiting astronomer George Abetti and gained responsibility for managing the 5-foot spectroheliograph and photographic darkroom dedicated to solar research. In 1912 Jennie B. Lasby was the first woman to observe with the 60-inch telescope, recorded in logbooks as "assisting" the observer. She would go on to observe more than 50 times, and though she was not credited as a co-author on Walter S. Adams’ publications with which she assisted, she did publish two articles in Popular Astronomy.

Carnegie's archivists continue to seek out more details about these women's vital contributions to our scientific legacy and will continue to spotlight them as new information is uncovered.

The formal Computing Division was disbanded in 1940 and its staff were made members of the research department with which their work was most closely aligned. In the 1960s, modern computing methods replaced the analog work done by human computers, and by the 1980s, no “computing” positions remained at the Carnegie Science Observatories.

The women of Mount Wilson Observatory’s Computing Division were often overlooked and undervalued in their time. They appear in few surviving photographs and are less well documented in published articles and archival records than the Observatory's male astronomers. It is easy to continue to overlook and undervalue their contributions. Yet they were an essential component of the community at Carnegie's Mount Wilson Observatory and played crucial roles in the discoveries made there. Today, it is critical that we recognize the significance of their work, despite the constraints placed upon them, and shine a spotlight on their experiences as an important part of the history of our community.