Perkins Observatory were both growing. Light pollution therefore became increasingly problematic. So in 1961 the Perkins Telescope was moved to Lowell Observatory in Flagstaff, Arizona. Lowell is the largest private observatory (non-university or government affiliated) in the world. Through the end of the 20th century, the Perkins Telescope was the observatory’s largest instrument. Observing time on this instrument was shared between Lowell astronomers and the Ohio State University. The telescope at Perkins was immediately replaced with a cassegrain reflector telescope. It was donated by Michael R. Schottland, an entrepreneur from Martinsville, Virginia. At that time it was the largest privately owned telescope
Goldendale Observatory State Park and north dome a diameter of 10 feet (3 m). The observatory served as the National Astronomical League's official headquarters during a solar eclipse which occurred on February 26, 1979, six years after the observatory opened. Approximately 15,000 people came to the town of Goldendale on that date to observe the eclipse. The Observatory and its lands were acquired by the state of Washington in 1980, after being operated by the Goldendale Observatory Corporation since its dedication on October 13, 1973. The park received its new designation as a "state park heritage site" in 2014. In July 2017, all structures