Search for Muons from the Direction of Cygnus X-3

Abstract Muons and multimuons detected in the Frejus underground nucleon decay detector between February 1984 and January 1986 have been analyzed. No excess events are observed in the direction of Cygnus X-3, which yields a 90% confidence level upper flux limit of 0.8 × 10 −12 cm −2 s −1 , for an average rock overburden of 5000 hg cm −2 corresponding to energies ⪆ 3 TeV. Using the 4.79 h periodicity of Cygnus X-3, no signal is found in any phase interval.