Key points are not available for this paper at this time.
Spectroscopic and photometric observations were carried out for HD 77581, a B0.5 Ib star located in the error box of the X-ray source 2U 0900-40. HD 77581 is identified as spectroscopic binary with a provisional period of 7.0 days and a semiamplitude of 26 km/sec. The minimum mass of the secondary star is near 1.4 solar mass.
Hiltner et al. (Sat,) studied this question.