The horn cluster is located approximately at the focal point of a parabolic reflector. The reflector is a spherical reflector, not a parabolic reflector. The Transit Telescope was a parabolic reflector zenith telescope built in 1947. The light pipe is attached to the parabolic reflector of the sulfur lamp. German physicist Heinrich Hertz constructed the world's first parabolic reflector antenna in 1888. All DSN antennas are steerable, high-gain, parabolic reflector antennas. Where multiple LEDs are used, each one may be put in its own parabolic reflector. Nevertheless, it is easily distinguished from a parabolic reflector by its flat or tube shape. One typical embodiment uses a horn feed antenna and a parabolic reflector to accomplish this. This parabolic reflector can serve as the primary mirror of a reflecting telescope. In 1888, Heinrich Hertz, a German physicist, constructed the world's first parabolic reflector antenna. The primary reflector is a parabolic reflector and the secondary reflector is a spherical reflector.