THE BEST CANDIDATE TO A BLACK HOLE-X-RAY NOVA V404 CYGNI - THE LIGHT-CURVE AND THE PARAMETERS

The optical light curve of V404 Cyg, convolved with the spectroscopic period P = 6,d47259 and the initial epoch JD 2448477,353, shows a cons iderable effect of ellipticity (0,m3). The behaviour of both light and radial-velocity curves is in agreement with a model of a binary syste m, confirming the correctness of the mass function f(v)(M) = 6,26 M.. It means that it is a bright G-K star that is the <<donor>> in the sys tem and transfering its mass to the relativistic object. The parameter s of the binary system, determined from light curve analysis, suggest a conclusion that V404 Cyg is the best candidate to a black hole.