ABSTRACT
Based on 27 blue spectrograms obtained between May 1984 and March 1985 with the Cassegrain IT spectrograph of the Cerro Tololo Inter-American Observatory, Chile, the spectrographic orbital elements of the massive O-type eclipsing binary are determined for the first time. From the ratios of the equivalent widths of the He I 4471 A and He II 4541 A absorptions of about 1.2 and 1.6 for the primary and secondary, spectral types of O7.5 and O8.5 are implied. Using the orbital elements derived from the He lines, minimum dimensions and masses of f15.8 + or - 0.3 solar radii and 23 + or - 1 solar masses for the primary, and 17.6 + or - 0.3 solar radii and 21 + or - 1 solar masses for the secondary, are derived.