Coming Soon: A New Telescope Array Hunting for Extragalactic Gamma Rays

On Monday, the Council of the Cherenkov Telescope Array Observatory signed a deal with the Instituto de Astrofísica de Canarias to place 19 telescopes on the island of La Palma in the Canary Islands. The site, located on a high-altitude plateau near the rim of an extinct volcanic crater, will allow the pristine viewing conditions for spotting the bits of blue light known as Cherenkov radiation that are characteristic of high-energy gamma rays smashing into Earth’s upper atmosphere.

By Michael Byrne | MOTHERBOARD

It’s these rays that are the experiment’s ultimate quarry. Once complete, the Cherenkov Telescope Array (CTA) will be able to spot incoming gamma rays with a precision 10 times that of the current best instruments. The Canary Islands array will be only the Northern Hemisphere portion of the CTA, with another 99 telescopes to be installed at a site in Chile. (The second site is still being negotiated with its European Southern Observatory landlord.) The two arrays combined will allow access to observations from across the whole sky and across a wide range of energies.

The telescopes in question are Imaging Atmospheric Cherenkov Telescopes (IACTs). They look very cool, particularly on a foggy night when the laser beams used to focus their mirror arrays are visible. These mirrors are used to focus ultrashort bursts of light—Cherenkov radiation—into photomultiplier tubes, which are coupled to electronics that perform quick data analyses on the events.

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