Grote Reber's radio telescope. This early radio telescope was made in 1937 by US radio astronomer Grote Reber (1911-2002). Reber's telescope was built in his back yard in Wheaton, Illinois, USA. It was the second radio telescope ever built, and the first to use the parabolic design. Radio sources in the sky that were observed for the first time with this radio telescope include Cassiopeia A and Cygnus X-1. It was later put on display at the National Radio Astronomy Observatory (NRAO) at Green Bank, West Virginia, USA. It was placed on the National Register of Historic Places in 1972, and declared a National Historic Landmark in 1989. Photographed in 2015.