Absolute low-latitude sea-level muon intensity at large zenith angle

The absolute sea-level cosmic-ray muon intensity has been estimated by using a flash-tube range spectrograph at axial zenith angles 75°-85° W near the geomagnetic equator in the cutoff-momentum region 0.4 GeV/c. The measured absolute muon intensity agrees with the results calculated in the manner of Ashton et al., assuming $\frac{K}{\pi }=0\mathrm{}$ for zenith angles up to 81° W and $\frac{K}{\pi }=0.4\mathrm{}$ for 85° W. The angular distribution of muons obeys a cosine-swuare law. The measured absolute integral muon spectrum at axial zenith angle 81° W in the cutoff-momentum interval 0.4-3 GeV/c agrees with the theoretical spectral shape calculated in the manner of Barrett et al.