127800
Gamma-rays in the MeV range are generated in solar flare s ( and even in the Earth 's atmosphere ) , but gamma-rays in the GeV range do not originate in our solar system and are important in the study of extrasolar , and especially extra-galactic astronomy .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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