A long-period comet detected by the Infrared Astronomical Satellite (IRAS) on 1983 April 25, and found independently on May 3 by the Japanese amateur astronomer Genichi Araki (1954– ) and the English amateur George Eric Deacon Alcock (1912–2000); formerly designated 1983 VII. It made an unusually close passage of 0.031 au (4.6 million km) to Earth on 1983 May 11, when it was of 2nd magnitude and moving rapidly across the northern sky. Because of its proximity to Earth, the comet appeared diffuse, with a diameter of 2°. Perihelion, 0.99 au from the Sun, was on 1983 May 21. Its orbit has a period of about 960 years, eccentricity 0.990, and inclination 73°.3.