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November 9, 2012

FORTIN: We have each telescope send a signal when each telescope thinks that there's a nice gamma-ray. Then we combine the signal from all four telescopes...

Pascal Fortin is an astronomer with VERITAS -- an odd-looking array of four telescopes in southern Arizona that's designed to probe some of the most energetic objects in the universe.

VERITAS is looking for flashes of light produced when gamma rays strike molecules high in Earth's atmosphere. Each collision generates a cascade of other collisions, and each of those can produce a flash of blue light that lasts for a few billionths of a second. High-speed cameras on the telescopes record the flashes.

Gamma rays come from quasars, pulsars, gamma-ray bursts, and the remnants of exploded stars, among other exotic objects. So studying them can reveal the conditions in the most extreme environments in the universe.

The brightest gamma-ray object is the Crab Nebula -- the remains of a star that was seen to explode almost a millennium ago. It consists of a neutron star, which pumps out a wind of charged particles, and a surrounding cloud of debris from the explosion. When the wind hits the debris, it produces gamma rays.

Gamma rays are invisible to the human eye, but the Crab also produces visible light. Through a telescope, it looks like a fuzzy blob with glowing tendrils. It's well to the lower left of brilliant Jupiter and the "eye" of Taurus, which are in the east during the evening hours.


Script by Damond Benningfield, Copyright 2012

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