  The atmospheric muon flux is generated with CORSIKA 6.030 (using QGSJET
high-energy interaction model) and fitted with the formula from Gaisser (1990).
Spectra and mass distribution of primaries were taken according to the
poli-gonato model of Horandel (2003). A convenient parameterization of the
cos(th)->cos(th*) correction, originally tabulated in Volkova (1969), is
presented. This correction, together with muon energy losses and decay, is
shown to significantly improve the fit to the simulated data.
