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, which was created by Frank Drake for Project Ozma – the world’s first scientific search for extraterrestrial intelligence – for use on the 40-Foot Telescope.
More than 1,500 students ranging from 5th graders to graduate students use the telescope to investigate the radio universe every year.
sidtcl is a program (.exe format) that you can run on your computer to convert between local sidereal time ( also known as the Right Ascension over the 40 foot) and Eastern time. The program will convert time for the 40-Foot, GBT, and 20M telescopes.
Right-click this link to download the program.
Thirty Years on the Forty Foot Telescope, by Sue Ann Heatherly
December 16, 1960: Letter to Antenna Systems, Inc. from Dave Heeschen
April 26, 1961: Letter to the National Science Foundation from Otto Struve
August 10, 1961: Letter to the National Science Foundation from John Findlay
September 6, 1961: Letter to F.J. Callender, Observatory business manager, from Dave Heeschen
December 29, 1960: NRAO News, 40 Foot Telescope update on page 6
February 10, 1962: Positioning log
February 9, 1962: Calibration line print
February 26, 1962: The Observer, 40 Foot Telescope update on page 1
If you have a story about the 40 Foot Telescope to share, please reach out!
In 1997, I was finishing high school and dating a young lady that was doing an astronomy project using the 40-Foot telescope. She told me one day that she was doing an all-night observation of some source, changing something in the observation every 5-10 minutes — I can’t recall if it was switching polarization, or […]
Some of you may remember David Heeschen. He was the first astronomer to be hired by the brand-new National Radio Astronomy Observatory, in about 1956. He was NRAO director 1962-1978. He facilitated the building of the VLA and is sometimes called the “father of the VLA”, which was completed in 1980. But before that, in […]
My times with the 40-foot are selfish ones. I’ve been in the bunker hundreds of times, often with teacher groups and student groups, but also many times alone. Those are some of my most cherished 40-Foot memories. Walking through snow from the dorm to the bunker in the early morning hours, sometimes lit by a […]
In the midst of celebrating the 60th anniversary of the Observatory at Green Bank, it’s easy to overlook another anniversary. July, 2017 marks the 30th anniversary of educational programs at the Green Bank Observatory. In July 1987, the Green Bank facility opened its doors to 27 teachers in an experimental two-week summer institute, designed to […]