  The results of photometric CCD monitoring and spectral observations of the
black hole binary and microquasar V4641 Sgr in the quiet state are presented.
The ellipsoidal light curve with large amplitude of 0.36^m in R band suggests
the influence of a massive object orbiting around a normal B9 star. In the
spectra taken with the 6-m telescope one hour before black hole inferior
conjunction, an absorption component in the red wing of Halpha line is visible.
It is formed by gaseous stream moving in the direction to the normal star. That
suggests the grazing conjunction in this system. Maximum velocity of the stream
is of 650 km/s. Assuming that the stream is moving through the circular
Keplerian orbit around black hole, the mass of the black hole is determined to
be M_{BH}=7.1-9.5Msun, what confirms the model by Orosz et al.
