The German cartographer Johann Bayer used the Greek letters alpha through lambda to label the most prominent stars in the constellation. Bode added more, though only Psi Crateris remains in use. John Flamsteed gave 31 stars in Crater and the segment of Hydra immediately below Crater Flamsteed designations, naming the resulting constellation Hydra et Crater. Most of these stars lie in Hydra. The three brightest stars—Delta, Alpha and Gamma Crateris—form a triangle located near the brighter star Nu Hydrae in Hydra. Within the constellation's borders, there are 33 stars brighter than or equal to apparent magnitude 6.5.