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symbo symbo
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7 years ago
For an astronomer, what is the “water hole”?

(a)   A range of noise-free frequencies between the microwave emission lines of hydrogen and hydroxyl
(b)   A range of noise-free frequencies near the 21-cm emission line of hydrogen
(c)   A gathering place for gnus
Textbook 
Discovering the Universe

Discovering the Universe


Edition: 7th
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discovererdiscoverer
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symbo Author
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7 years ago
Thanks
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You make an excellent tutor!
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Brilliant
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