The Hartung–Boothroyd Observatory (HBO) is located atop Mount Pleasant near the Cornell University in Ithaca, New York (USA). It is used mainly as a teaching facility for upper-level astronomy classes.
The observatory is named in honor of M. John Hartung and Samuel L. Boothroyd. The telescope construction began in the 1930s and the observatory was built in 1974. The facility contains a 25-inch telescope and is equipped with various instruments.
The main mirror was constructed as 1/8-scale practice before making the 200-inch Palomar Observatory mirror. This test mirror sat in storage for many years before being put to good use at HBO.