if the govern ment made the aurora then why do they keep it a secret

i mean so many people in southern colifornia heard the sonic booms around southern california(close to area 51 ) and if you put a dot in every place (in southern california) and you trace it it will go in a circle startin close to area 51 and ending close to area 51 so why keep it a secret if almost every body heard it and seen it

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