The Algonquin Radio Observatory (ARO) is a radio telescope research facility located in Algonquin Provincial Park in Ontario, Canada. The site's primary instrument is a major 46 m (150 ft) parabolic-dish radio antenna.
This radio telescope is historically famous for taking part in the first successful very long baseline interferometry experiment in the 1960s, where it was experimentally arrayed with the 26-metre Telescope at the Dominion Radio Astrophysical Observatory near Penticton, British Columbia.
The site also formerly ran a solar-observing array of thirty-two 10 ft (3 m) dishes, and a single 1.8 m solar flux monitor observing at 10.7 cm wavelength. The site is currently used to provide high accuracy geodetic location information to the present day for applications such as real time GPS signal correction. The site has its own atomic clock, a standard feature for radio telescopes that can also serve to receive telemetry from Deep Space missions.