Edward Pickering was an American physicist and astronomer who was born in Boston on the 19th of July in 1846. He graduated in 1865 from the Lawrence Scientific School of Harvard. Here, for the next two years, he was a teacher of mathematics. Afterwards he became a professor of physics at the Massachusetts Institute of Technology, and in 1876 he was given the position of professor of astronomy and director of the Harvard College observatory.
In 1877 he made the choice to devote one of the telescopes of the observatory to stellar photometry, which I now know what it is thanks to our lab, and after he performed an exhaustive trial of various forms of photometers, he concocted the meridian photometer, which seemed to eliminate most of the factors that were causing error. What a meridian photometer is is as; an instrument in which mirrors are used to bring the light from two stars which are at or near the celestial meridian simultaneously, but at different altitudes, to a common focus, to compare their brightness. Using the fist instrument of this kind, having objectives of 1.5 inches aperture, he measured the brightness of 4260 stars, including all stars ascending to the 6th magnitude between the North Pole and -30° declination. With the objective of reaching fainter stars, Pickering constructed another instrument on a larger scale, and with this more than a million observations have been made. The first important work undertaken with it was a revision of the magnitudes given in the Bonn Durchmusterung. These were a series of astrometric star catalogues of the entire sky from the Bonn Observatory in Germany in the late 19th century leading into the 20th.
Once he finished this, Pickering decided to undertake the surveying of the southern hemisphere. An expedition, under the direction of Prof. S. I. Bailey, was accordingly dispatched in 1889, allowing the meridian photometer to be erected successively in three different positions on the slopes of the Andes. The third of these locations was Arequipa, at which a permanent branch of the Harvard Observatory still stands to this day. The magnitudes of up to 8000 southern stars were determined, including 1428 stars of the 6th magnitude and brighter. The photometer was then shipped back to Cambridge, Massachusetts, where the survey was extended to include all stars of magnitude 7.5 all the way down to -40° declination, after which it was once again sent back to Arequipa. In 1886 the widow of Henry Draper, one of the pioneers of stellar spectroscopy, requested that spectroscopic investigations be continued at Harvard College in memory of her husband. With Pickering's profusion, the inquiry was so arranged as to cover the entire sky; and with four telescopes, two at Cambridge for the northern hemisphere, and two at Arequipa in Peru for the southern. Due to this up to 75,000 photographs had been obtained up to the beginning of 1901. These investigations have yielded numerous important discoveries including an entirely new class of double stars whose binary character is only revealed by peculiarities in their spectra.
Edward Pickering died in Cambridge on February 3 in 1919. The cause of his death has not been specified.
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