THE ORBIT OF THE CLASSICAL CEPHEID U AQUILAE.

A total of 62 new radial-velocity observations of the classical Cepheid U Aql have been obtained during the interval 1969 - 86. The authors present the first determination of a spectroscopic binary orbit for this star. The orbital elements derived from both new and published velocities are given. IUE observations reported by Böhm-Vitense and Proffitt (1985) indicate the presence of an early-type main-sequence companion. The orbital elements combined with estimates of the companion mass result in upper limits for the mass of the Cepheid in the range 6.4 - 8.8 Msun;. The possibility of spatially resolving the system using interferometric techniques is discussed.