The Henry Draper Catalogue is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension, published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the Henry Draper Extension Charts, published from 1937 to 1949 in the form of charts, which gave classifications for 86,933 more stars. Wikipedia