Muon astronomy with the MACRO detector

We have analyzed a sample of 1.8 × 106 muons with Eμ ≳ 1.3 TeV collected by the first and second supermodules of the MACRO detector at Gran Sasso during the period 1989 February to 1991 February. We have searched for an excess of muons of celestial origin over cosmic-ray background. Our search for steady sources in solid angle bins of AΩ ≈ 3°.0 × 3°.0 in the declination range -5° ≤ δ ≤ 90° was negative; the upper limit with 95% C.L. to the muon flux at mid-latitudes (δ ∼ 45°) is Jsteadyμ ≲ 2 × 10-12 cm-2 s-1. In addition, we have searched for muon excesses modulated by the orbital period of selected X-ray sources, including Cyg X-3, Cyg X-1, Her X-1, 4U 0115+63, and 4U 1907+09. For Cyg X-3 we obtained an upper limit with 95% C.L. of Jmodμ ≤ 8.8 × 10-13 cm-2 s-1. Further, we have no evidence of any bursting activity from Cyg X-3, during our search period, which includes the radio outburst of 1991 January.