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Harvard College Observatory (HCO) astronomers, 1917. The employment of female assistants and astronomers at HCO, Cambridge, Massachusetts, USA, was an unorthodox move, but the women did a much more thorough job than the previous team of male assistants. They classified spectra for the Henry Draper Catalogue, and made a number of significant breakthroughs. Holding hands, left to right: Ida E. Woods, Evelyn F. Leland, Florence Cushman, Grace R. Brooks, Mary H. Vann, Henrietta S. Levitt, Mollie E. O'Reilly, Edith F. Gill, Alta M. Carpenter, Annie J. Cannon, Dorothy W. Block, Arville D. Walker, Frank E. Hinkley, and Edward S. King.
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