Edward Pickering was a prominent American astronomer who pioneered the development of the color index method for cataloging stars and who encouraged many young scientists in astronomy, including many women (which was unusually for the time). Pickering graduated from Harvard and then taught physics for 10 years at the Massachusetts Institute of Technology where he built the first instructional physics laboratory in the United States. Appointed at age 30 as director of the Harvard College Observatory, he served in this post for 42 years.
He and his staff made visual photometric studies of 45,000 stars. With funds provided by Henry Draper's widow, Anna Palmer Draper, he hired a number of women, including Williamina Fleming, Annie Jump Cannon, Antonia Maury, and Henrietta Levaitt, and produced the Henry Draper Catalogue with objective prism spectra of hundreds of thousands of stars classified according to Cannon's “Harvard sequence.” He established a station in Peru to make the southern photographs and published the first all-sky photographic map. He and Hermann Vogel (1842–1907) independently discovered the first spectroscopic binary stars. He also discovered a new series of spectral lines, now known as the Pickering series, that turned out to be due to ionized helium. Pickering encouraged amateur astronomers and was a founder of the American Association of Variable Star Observers.
Pickering made innovations in spectrography. Instead of placing a small prism at the focus to capture the light of a single star, he put a large prism in front of the objective, obtaining at the same time a spectrogram of all the stars in the field sufficiently bright to affect the emulsion. This made possible the massive surveys he wanted to organize and enabled the publication in 1918 of the Henry Draper Catalogue, compiled by Annie Cannon, giving the spectral types of 225,300 stars. The other innovation in instruments due to him was the meridian photometer introduced in 1880. In this, images of stars near the meridian would be reflected at the same time as the image of Polaris. The brightness could then be equalized and as the brightness of Polaris was known, that of the meridian stars could easily be calculated. More than a million observations with such instruments permitted the compilation of the Harvard catalog giving the magnitude of some 50,000 stars. He was able to include stars of the southern hemisphere in this catalog, for in 1891 he had established an observatory in Arequipa, Peru, with the help of his brother William Henry Pickering and published the first all-sky photographic map. He and Hermann Vogel (1842–1907) independently discovered the first spectroscopic binary stars. He also discovered a new series of spectral lines, now known as the Pickering series, that turned out to be due to ionized helium. Pickering encouraged amateur astronomers and was a founder of the American Association of Variable Star Observers.
