Henry Draper Catalogue
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The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 of the brightest stars visible from the northern and southern hemispheres.
The catalogue was first published between 1918 and 1924. It was compiled by Annie Jump Cannon and co-workers at Harvard College Observatory under the supervision of Edward C. Pickering, and was named in honour of Henry Draper, whose widow donated the money required to finance it.
Stars contained in the catalogue are of medium magnitude, down to about 9m (about 50 times dimmer than the faintest stars visible with the naked eye). This makes them average-looking in amateur telescopes, and bright stars for professional instruments. The catalogue covers the whole sky and is notable as the first large-scale attempt to catalogue spectral types of stars.
[edit] Consequences of Catalogue
The catalogue opened the systematic study of star's emissions which led to the correct ordering of stars by spectral sequence which implies a star's luminosity which gives us the Hertzsprung-Russell diagram.
HD numbers are widely used today for stars which have no Bayer or Flamsteed designation. Stars numbered 1-225300 are from the original catalogue and are numbered in order of right ascension for 1900.0 epoch. Stars in the range 225301-359083 are from the 1949 extension of the catalogue. The notation HDE is used only for stars in this extension (Henry Draper catalogue Extension), but even these are usually denoted HD as the numbering ensures that there can be no ambiguity.
