  V616 Mon = A0620-00 is a prototype of black hole transient X-ray binaries.
Our 2003-16 optical photometry of the object during X-ray quiescence, obtained
by 50-250 cm telescopes in Crimea, Caucasus Mountains and Slovakia, consists of
~ 7660 CCD frames in Johnson-Cousins $V,R,R_C,I$ bands and the integral light.
During 2003, 2008-9 and 2015-16 passive states, the phase light curve of the
binary exhibited mainly variations caused by an ellipsoidal shape of the red
dwarf component. During 2004-6 and 2009-14 active states a significant
aperiodic broad-band variability (flickering) was present, arising in a black
hole accretion disk and a bright spot, where the mass transfer stream hits the
outer edge of the disk. Long term photometry of our minima times, together with
available positions of superior conjunctions of the red dwarf found from
spectroscopy, allowed us to refine the orbital period of V616 Mon to
0.32301407(5) days.
