The world’s first and only radio sundial has been erected in memory of RON BRACEWELL, a professor of electrical engineering and a pioneer in radio astronomy. The sundial was unveiled at the Very Large Array (VLA) Radio Telescope Observatory in New Mexico. It was constructed using pieces of a famous radio telescope that Bracewell built near the Stanford campus.
Bracewell, who died in 2007, was a pioneer in the transition from giant dish antennae to radio telescopes comprised of large-scale arrays of antennae.
In 1961, he installed 32 dish antennae at Site 515 – an area west of campus near Alpine Road – to measure the sun’s temperature. The array, which Bracewell called “Heliopolis,” was one of the first in the world. NASA used the daily maps of solar activity it produced to plan the first moon landing.
“Since its humble beginnings, radio astronomy has become a very active field. Professor Bracewell was one of the heroes of the field,” said DAVID B. LEESON, a consulting professor of electrical engineering and one of the speakers at the dedication ceremony. “Modern giant arrays like the VLA owe their conceptual design to Bracewell’s experimental and mathematical vision.”
The radio sundial at the VLA was constructed using 10 of the concrete pillars that held the Heliopolis antenna dishes. (The array was dismantled several years ago.)
In addition to aligning with markers that tell the time of day, the shadow cast by the Bracewell Sundial’s gnomon – the center object of the sundial – will also indicate the approximate time of year. It will also fall on markers that point to important dates in the history of radio astronomy and to solar noon at other observatories.
And, unlike any other sundial in the world, it will also allow visitors to locate the approximate position in the sky of three celestial objects that played important roles in radio astronomy – two distant galaxies and the remains of an exploded star in the Milky Way.