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New Scientist
US SKIES are clearer than usual after the switch in June from analogue to digital TV freed up a chunk of the radio spectrum. Astronomers are now rushing to see what they can find before transmissions from cellphone companies and others fill the space.
Prior to the switch-over, naturally occurring radio waves at frequencies between 700 and 800 megahertz were obscured by analogue TV signals, preventing astronomers from investigating the universe using this band. Now a receiver has been installed at the Arecibo Observatory in Puerto Rico to take advantage of the new-found clarity.
The window is giving astronomers their first radio views of galaxies that thrived when the universe was about half its present age. They hope to measure how much hydrogen - the raw material for new stars - the galaxies had. "It's a once-in-a-lifetime opportunity to see galaxies in that range," says Arecibo researcher Chris Salter. "We're able to see an epoch that hasn't been observed before with radio eyes."
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