The Impact of the Henry Draper Catalogue on 20th Century Astronomy (Abstract)

Volume 28 number 2 (2000)

Barbara L. Welther

Abstract

(Abstract only) By 1900 there was a definite need to update the great star catalogues of the nineteenth century. First of all, the stellar coordinates in the Bonner Durchmusterung and other star catalogues were pinned to the epoch of 1875. Then, too, there was no systematic scale for stellar magnitudes. Finally, the nineteenth-century catalogues were all published before astronomers had any ideas, let alone data, for classifying large numbers of stars by their spectra. Under the leadership of Edward Pickering and the financing of Anna Palmer Draper, the work on the Henry Draper Memorial began at Harvard College Observatory in the late 1880s. Its primary goal was to gather and classify the photographic spectra of about 100,000 stars. As a test case, Pickering had Williamina Fleming develop a simple classification scheme and apply it to the spectra of about 10,000 stars. The Henry Draper Catalogue was published in 1890. For the next two decades, Pickering worked to have astronomers approve the Harvard Classification scheme before having Annie Jump Cannon begin the larger project of classifying 100,000 stars. Cannon was so efficient at classifying stellar spectra that she examined about 40,000 stars in the first year and 60,000, the second year, for a total of 100,000 in two years. Rather than limiting the project to that number at that time, she continued classifying spectra for another two years for a total of 225,300 stars in four years of work. Although Cannon completed the classification of the stars in 1915, the first of nine volumes of the Henry Draper Catalogue was not published until 1918. At that time, it was greeted with enthusiasm and congratulations from eminent astronomers around the world: Jacobus Kapteyn in the Netherlands, Herbert Hall Turner in England, Harlow Shapley in California, to name a few. Subsequently, the HD Catalogue has continuously been a source of data for all sorts of investigations of the Milky Way. Today, the data in it are now available online and are still widely used as a coherent source for a variety of ongoing investigations.