A small but distinctive constellation of the northern sky, popularly known as the Northern Crown. It features a prominent arc of stars, the brightest of which is Alpha Coronae Borealis (Alphecca). It contains two remarkable variables: R Coronae Borealis, the prototype of a group that undergoes sudden dips in light output (see R Coronae Borealis star); and T Coronae Borealis, a recurrent nova known as the Blaze Star.