Friday, December 11, 2009

"Pickering's harem" and Annie Jump Cannon

A print of this HCO photograph was found in an album that had once belonged to Annie Jump Cannon. The print was dated by tracing the HCO serial number on it to the record books in the Harvard College Observatory Collection of Astronomical Photographs. The women were identified by comparing the print to other HCO photographs on which Margaret Harwood or Annie Jump Cannon had noted the names.

This picture which includes Edward Charles Pickering, the Director of HCO (1877-1919), was taken on 13 May 1913 in front of Building C, which faces north. At that time it was the newest and largest building of Harvard College Observatory. It was specially built of brick to protect the astronomical data and glass negatives from fire. Since the astronomical photographs were stored on the ground floor and most of the women worked on the top floor, the building had a dumb waiter to convey the plates up and down. The women all worked in a large room on the east end of the third floor. Pickering had his offices on the west end across the central hallway. All the other men worked on the lower levels.

At the far left of the photograph is Margaret Harwood (AB Radcliffe 1907, MA University of California 1916), who had just completed her first year as Astronomical Fellow at the Maria Mitchell Observatory. She was later appointed director there, the first woman to be appointed director of an independent observatory. Beside her in the back row is Mollie O'Reilly, a computer from 1906 to 1918. Next to Pickering is Edith Gill, a computer since 1989. Then comes Annie Jump Cannon (BA Wellesley 1884), who at that time was about halfway through classifying stellar spectra for the Henry Draper Catalogue. Behind Miss Cannon is Evelyn Leland, a computer from 1889 to 1925. Next is Florence Cushman, a computer since 1888. Behind Miss Cushman is Marion Whyte, who worked for Miss Cannon as a recorder from 1911 to 1913. At the far right of this row is Grace Brooks, a computer from 1906 to 1920.

Ahead of Miss Harwood in the front row is Arville Walker (AB Radcliffe 1906), who served as assistant from 1906 until 1922. From 1922 until 1957 she held the position of secretary to Harlow Shapley, who succeeded Pickering as Director. The next woman may be Johanna Mackie, an assistant from 1903 to 1920. She received a gold medal from the American Association of Variable Star Observers (AAVSO) for discovering the first nova in the constellation of Lyra. In front of Pickering is Alta Carpenter, a computer from 1906 to 1920. Next is Mabel Gill, a computer since 1892. And finally, Ida Woods (BA Wellesley 1893), who joined the corps of women computers just after graduation. In 1920 she received the first AAVSO nova medal; by 1927, she had seven bars on it for her discoveries of novae on photographs of the Milky Way.

Barbara L. Welther published the photograph and some of the text in a note about "Pickering's Harem" in Isis 73, 94 for March 1982.

Moreover, it is Annie Jump Cannon's birthday.

Bill Ashworth of Linda Hall Library Newsletter wrote:

Annie Jump Cannon, an American astronomer, was born Dec. 11, 1863. She graduated from Wellesley College in Massachussetts, and went back there for graduate study in 1894, just when they began to teach courses in astronomy. In 1896, she was conscripted into what was called "Pickering's harem"--a group of women hired by Edward Pickering, director of Harvard College Observatory, to undertake the Herculean project of classifying all the stars by their spectra. The Draper Project, as it was known after the fellow whose estate funded all this, was over ten years old when Cannon joined, and was presided over by Williamina Fleming. Fleming had been assigning letters of the alphabet to groups of stars, with "A" stars being those with the most hydrogen, "B" Stars the next most, and so on. Cannon's bright idea was to sort the stars by temperature. This caused the order to be reshuffled, leaving us with the familiar OBAFGKM sequence--familiar, that is, to anyone who has taken a course in astronomy. Cannon herself classified over 230,000 stars in her tenure at the Observatory, an unfathomable number, when you consider that the spectrum of each star had to be observed, individually, with a magnifying loupe, on a glass photographic plate.

Unknown source...

Born: Dover, Delaware, December 11, 1863
Died: Cambridge, Massachusetts, April 13, 1941
Theorist of Star Spectra

Oh, Be A Fine Girl--Kiss Me! This phrase has helped several generations of astronomers to learn the spectral classifications of stars. Ironically, this mnemonic device, still used today, refers to a scheme developed by a woman.

Annie Jump Cannon was the eldest of three daughters of Wilson Cannon, a Delaware shipbuilder and state senator, and his second wife, Mary Jump. Annie's mother taught her the constellations and stimulated her interest in astronomy. At Wellesley, Annie studied physics and astronomy and learned to make spectroscopic measurements. On her graduation in 1884, she returned to Delaware for a decade, but became impatient to get back to astronomy. After the death of her mother in 1894, Cannon worked at Wellesley as a junior physics teacher and became a "special student" of astronomy at Radcliffe.

In 1896, she became a member of the group that historians of science have dubbed "Pickering's Women," women hired by Harvard College Observatory director Edward Pickering to reduce data and carry out astronomical calculations. Pickering's approach to science was thoroughly Baconian: "the first step is to accumulate the facts."* The accumulating was supported by a fund set up in 1886 by Anna Draper, widow of Henry Draper, a wealthy physician and amateur astronomer.

Pickering conceived the Henry Draper Memorial as a long-term project to obtain optical spectra of as many stars as possible and to index and classify stars by their spectra. While the measurements were difficult enough, the development of a reasonable classification scheme proved as much a problem in "theory" (which Pickering was slow to recognize) as "fact accumulation."

The analysis was begun in 1886 by Nettie Farrar, who left after a few months to be married. Her place was taken by Williamina Fleming, the first of Pickering's female crew to be recognized in the astronomical community at large. Fleming examined the spectra of more than 10,000 stars and developed a classification system containing 22 classes. The work was carried further by Antonia Maury, who developed her own classification system. The system was cumbersome by comparison with Fleming's, and Pickering could not sympathize with Maury's insistence on theoretical (what we would today call astrophysical) concerns that underlay her scheme.

It was left to Annie Jump Cannon to continue, beginning with an examination of bright southern hemisphere stars. To these she applied yet a third scheme, derived from Fleming's and Maury's, an "arbitrary" division of stars into the spectral classes O, B, A, F, G, K, M, and so on. It was as "theory-laden" as Maury's ordering, but greatly simplified. Her "eye" for stellar spectra was phenomenal, and her Draper catalogs (which ultimately listed nearly 400,000 stars) were valued as the work of a single observer.

Cannon also published catalogs of variable stars (including 300 she discovered). Her career spanned more than forty years, during which women in science won grudging acceptance. She received many "firsts" (first recipient of an honorary doctorate from Oxford, first woman elected an officer of the American Astronomical Society, etc.). At Harvard she was named Curator of Astronomical Photographs, but it was only in 1938, two years before her retirement, that she obtained a regular Harvard appointment as William C. Bond Astronomer.

* Quoted by Pamela Mack in her article, "Straying from their orbits: Women in astronomy in America," in G. Kass-Simon, P. Farnes, and D. Nash, 1990: Women of Science: Righting the Record (Bloomington, Indiana University Press), p. 91.

Annie Jump Cannon [Wikipedia]

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