  The inverse problem of cosmic ray transport of ultra-high energy cosmic rays
is considered. The analysis of Auger data on energy spectrum, energy dependence
of mean logarithm of atomic mass number and its variance allows definite
conclusions on the shape of the source spectrum in the frameworks of the
inverse problem approach. The discussion on regularization procedure for
considered ill-posed problem is presented.

High Energy Astrophysical Phenomena;High Energy Physics - Phenomenology