Collinder 399

CR 399, also known as Collinder 399 or the Coathanger Cluster, is a striking asterism in the constellation Vulpecula. Although it was once thought to be an open star cluster, modern measurements show that the stars lie at different distances — on average between 200 and 1,200 light years — so it is not a physically connected group but an optical illusion.

Its striking shape resembles a coathanger: a line of stars forms the “bar” and a vertical chain the “hook”. About ten stars with magnitudes between 5 and 7 are already clearly visible in binoculars.