Calculation of Neutrino Flux from Cygnus X-3

We estimate the flux of neutrinos produced by protons accelerated by the compact partner in Cygnus X-3. Such neutrinos are produced in collisions with the atmosphere of the companion, and there can be substantial modulation due to absorption in the companion. The resulting flux of upward muons induced by neutrinos in rock below an underground detector is at the level of 1 per 1000 ${\mathrm{m}}^2$ per year.