GL MARK III C-band Radar and APF trailer

The photograph shows the equipment during testing in 1941.

The parabolic antennas of the GL MARK III C-type radar are amounted on a trailer known as an Accurate Position Finder (APF). The purpose of this type of system, also known as a Ground Coastal Radar, developed at the National Research Council of Canada, was to detect enemy aircraft. The Canadian army finally selected it for installation along the St Lawrence River in 1943.

Reproduced with the authorization of the National Research Council of Canada

Haystack Observatory

The MIT Haystack observatory is about an hour outside of Boston. The dish antenna inside the radome (a golf ball like structure but it only repeats about 3 times) measures 37 meters in diameter (over 100 feet). Scientists operate the giant antenna (dish) in the building under the radome. Many experients take place here, for example: "one of the more impressive ideas presented by the speakers involved masers, which glow inside large molecular clouds. Their use is a very clever way to map movement of the gases in distant nebula and galaxies."