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Use "arcsec" in a sentence
"Fading from mag -2.6 to -2.4 and shrinking in diameter from 43 to 39 arcsec during the month, it is conspicuous near the Moon on the 2nd and again on the 30th."
"Mars, slow-moving below Leo's hindquarters, doubles in brightness from mag 0.2 to -0.6 as its distance plummets from 156 million to 119 million km and its diameter swells to 12 arcsec."
"Catch it 6° below-left of the earthlit crescent Moon on the 26th when its gibbous disc is 15 arcsec across."