bright star Altair. Covering 79.9 square degrees and hence 0.194% of the sky, Sagitta ranks 86th of the 88 modern constellations by area. Only Equuleus and Crux are smaller. Sagitta is most readily observed from the late spring to early autumn to northern hemisphere observers, with midnight culmination occurring on 17 July. Its position in the Northern Celestial Hemisphere means that the whole constellation is visible to observers north of 69°S. Sagitta is bordered by Vulpecula to the north, Hercules to the west, Aquila to the south, and Delphinus to the east. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Sge"; American astronomer Henry Norris Russell, who devised the code, had to resort to using the genitive form of the name to come up with a letter to include ('e') that was not in the name of the constellation Sagittarius. The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of twelve segments (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between and , while the declination coordinates are between 16.08° and 21.64°. Notable features Stars Celestial cartographer Johann Bayer gave Bayer designations to eight stars, labelling them Alpha to Theta. English astronomer John Flamsteed added the letters x, mistaken as Chi (χ), y and z to 13, 14, and 15 Sagittae in his Catalogus Britannicus. All three were dropped by later astronomers John Bevis and Francis Baily. Bright stars Ptolemy saw the constellation's brightest star Gamma Sagittae as marking the arrow's head, while Bayer saw Gamma, Eta, and Theta as depicting the arrow's shaft. Gamma Sagittae is a red giant of spectral type M0 III, and magnitude 3.47. It lies at a distance of from Earth. With around 90% of the Sun's mass, it has a radius 54 times that of the Sun and is 575 times as bright. It is most likely on the red-giant branch of its evolutionary lifespan, having exhausted its core hydrogen and now burning it in a surrounding shell. Delta Sagittae is the second-brightest star in the constellation and is a binary. Delta and Zeta depicted the spike according to Bayer. The Delta Sagittae system is composed of a red supergiant of spectral type M2 II that has 3.9 times the Sun's mass and 152 times its diameter and a