The Georgetown University Astronomical Observatory (also the Heyden Observatory and Francis J. Heyden Observatory) was founded in 1841 by Father James Curley of the Department of Physics at Georgetown College. Father Curley chose a site on the College grounds, planned the building and supervised its construction to its completion in 1844. Costs were initially supported by Rev. Thomas Meredith Jenkins, S.J., and Rev. Charles H. Stonestreet, S.J., who were Georgetown professors at the time. The Observatory was used in 1846 to determine the latitude and longitude of Washington, D.C., which Curley determined to be longitude 38°54′26N and latitude 5h8m18.29s.
In 1850, Benedict Sestini used the Observatory to make a series of sunspot drawings, which were engraved and published (44 plates) as "Appendix A" of the Naval Observatory volume for 1847, printed in 1853. In 1888, Johann Georg Hagen was named director. In 1928, Paul McNally became director. Francis J. Heyden, S.J. became director in 1945, and continued research into solar eclipses. In 1972 the Department of Astronomy was closed, and with it the Observatory, which was renamed for Father Heyden, fell out of use. Light pollution from surrounding Washington, D.C. has limited viewing celestial bodies from the location.
On July 2, 1973, the Observatory was named to the National Register of Historic Places. The Georgetown University Astronomical Society has, with support of Department of Physics and Georgetown University, periodically sponsored renovation of the Heyden Observatory, which is now primarily used by the Laboratory of Entomology and Biodiversity. The Heyden Memorial Garden is on the east and north sides of the Observatory. The Garden has flowers, fountains, ponds, and trees. The plants are native and nonnative species. In 1989, as part of GU's bicentennial celebration, Professor Donald M. Spoon, who had a lab in the Observatory at the time, organized the dedication of the garden. Father Heyden attended the ceremony. At the time, the garden was full of hundreds of Iris species and cultivars, including new ones that Professor Spoon bred.