The Manastash Ridge Observatory (MRO) is an astronomical observatory built in 1972 by the University of Washington. It is located in a remote area approximately 14 kilometers (8.7 mi) west of Ellensburg, Washington, and can be reached by dirt roads from Ellensburg or Selah. The observatory features a 0.75 m (30 in) Ritchey-Chrétien telescope built by Boller and Chivens. Initially used for professional and graduate research, the observatory is now used mostly by undergraduate students for instruction and research.
The Manastash Ridge Radar (MRR) is located in the MRO building. MRR is a bistatic, passive radar controlled by the University of Washington's Radar Remote Sensing Laboratory (RRSL) led by Dr. John Sahr. MRR uses commercial FM radio broadcasts from Seattle to sense ionospheric turbulence, meteors, and airplanes. The receivers are located at the University of Washington and at MRO.