ABSTRACT
Based on 26 observations obtained between 1977 and 1985 with the Cassegrain and coude spectrographs, revised orbital elements for the semiregular variable RR U Mi are presented, including a period of 748.9 days, T = JD2444419, e = 0.13, V0 = 6.2 km/s, and alpha sin i = 8.4 x 10 to the 7th km/s. The reduction in the mean errors of single observations and the uncertainties in individual elements are not as great as expected, and a limit to precision may be set by radial motions within the atmosphere of the M star which are related to the variability of the star. No feature is noted in the spectrum that can be ascribed to a secondary spectrum.