The 40ft 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). As far as we know, it was the first completely automated telescope. After sitting idle for nearly 2 decades, the 40′ was recommissioned in 1987 as an educational telescope.
Cool fact: 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.
More than 1500 students ranging from 5th graders to graduate students use the telescope to investigate the radio universe every year!
- Volunteer engineer Skip Crilly has improved the 40 Foot through installation of fiber optics. The receiver bandpass is now: 1340 MHz to 1580 MHz
- The updated 40′ manual  is available as a PDF file.
- Here is a program  you can install to convert between local sidereal time ( also known as the Right Ascension over the 40 foot) and Eastern time.
- Published research using 40 Foot Data! The fading of Cassiopeia A: On Astro-ph