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Its story

Theta Circini is a hot blue Be-type star, a Gamma Cassiopeiae variable whose brightness oscillates between magnitudes 4.86 and 5.13 over very short cycles of six and a half hours. It shines from more than fifteen hundred light-years away in the southern Compasses, a constellation Lacaille fixed in the eighteenth century right next to the foot of Centaurus. Its true luminosity exceeds two thousand suns, but distance dims it until it barely registers to the unaided eye.