example program for skimming or upgoing showers
the EAS simulations in the examples (corsika.cpp, vertical_EAS.cpp etc) cover only the standard scenario of a downgoing EAS.
ShowerAxis
and other bookkeeping devices probably need an update for earth/atmosphere skimming and upgoing showers. Issue #499 suggests that there are already problems for downgoing showers at large inclinations.
Before extending corsika.cpp it may be easiest to add a new example for skimming/upgoing showers.