The 40ft Telescope


The 40-ft Telescope

In 1961, a 40-foot telescope was ordered from Antenna Systems, Incorporated and delivered to our growing observatory in Green Bank, West Virginia. This inexpensive aluminum telescope took only two days to set up and began observations on December 14, 1961.

The 40-foot telescope can only move in one direction, up and down. It relies on the Earth’s rotation to swing it underneath the space objects it observes. With a control system designed and built by NRAO staff, on February 1, 1962 the 40-foot became the world’s first fully automated telescope.

The 40-foot provided us with an unmanned observing program focused solely on radio sources whose brightness changes over time. Its five-year mission observed eight radio sources every day: 3C 48, 3C 144 (Taurus A, aka Crab Nebula), 3C 218 (Hydra A), 3C 274 (Virgo A), 3C 295, 3C 358, 3C 405 (Cygnus A), and 3C 461 (Cas A).

After sitting mostly idle for nearly two decades, the 40-foot was recommissioned in 1987 as an educational telescope and has been in use ever since. Students ranging from 5th graders to graduate students use the telescope to investigate the radio universe. The Education in Radio Astronomy (ERIRA) one-week summer workshop comes to Green Bank every year to use the 40-foot. Teachers from Radio Astronomy Research Enhancing Coordinated and Thematic Science (RARE CATS) complete extensive research projects using the 40-foot, and Chautauqua Short Course participants have access as well. In addition, amateur astronomers routinely make use of this telescope.

Stats for the 40-ft telescope

Receiver: 1350 MHz to 1430 MHz

We repurposed the Tatel Telescope’s 1960 feed that was created by Frank Drake for Project Ozma, the world’s first scientific search for extraterrestrial intelligence.

The spectrometer of the 40-foot comes from our old 300-foot telescope that collapsed in 1988.


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