Henrietta Hill Swope
was born on October 26, 1902 in St Louis, Missouri, USA. She got her master's degree in astronomy while working with Harlow Shapley, the director of the Harvard College Observatory.
Swopes's most important work was on variable stars, in particular Cepheid variables. Careful measurements of the variability of these stars made it possible to determine their distance. (This understanding was based on the work of Henrietta Leavitt
who had previously worked at the Harvard College Observatory.)
In 1952, Swope went to California to work with Walter Baade on the variable stars detected by the new 200-inch Hale Telescope at Mount Palomar
. It was owned by the Carnegie Institution. The largest telescope in the world (at that time) made it possible to use variable stars in other galaxies to determine their distances. She spent the rest of her career working there.
Retirement didn't end her contributions to astronomy. She had family money, and donated a large sum to the Carnegie Institution to develop optical astronomy facilities in the southern hemisphere. The Swope Telescope at Las Campanas Observatory in Chile is still in use. When she died, she left most of her estate to support Las Campanas.