An X-ray binary about 15 000 l.y. away in the constellation Aquila, consisting of a hot supergiant with a compact companion, probably a black hole of about 16 solar masses. It lies in an old supernova remnant designated W50, which is presumably the debris of the event that produced the compact object. The binary has an orbital period of 13.1 days and appears optically as a variable star, V1343 Aquilae, of 14th magnitude. An accretion disk around the compact object emits over half the light output of the system. SS433 is notable for the twin jets of gas being expelled from the face of the accretion disk at 78 000 km/s (about one-quarter the speed of light). Precession of the accretion disk causes the jets to sweep out a 40° cone which is perpendicular to the face of the disk. The jets are visible at radio, optical, and X-ray wavelengths. SS 433 is sometimes described as a microquasar.