Excerpt from the Copyright file included with the tarball:
Permission to build and run XEphem from this source code is granted only
for personal use or for bona fide educational situations or research funded
by public funds. Permission is expressly prohibited in commercial or
military situations without prior agreement.
XEphem source code may not be used, in whole or in part, to build other
computer programs under any circumstances without prior agreement.
Redistribution rights: You may redistribute XEphem source code only in its
entirety and without modification. You may redistribute binaries only if
they were built from the original source code, or from source code with
very minor changes made for the purpose of porting and not for the purposes
of changing functionality.
This is _not_ Free Software, but has usage restrictions and allows only unmodified redistribution. LICENSE should be changed to "free-noncomm" (which would still be approximate only), or the xephem license should be added to the tree.
+ 30 Sep 2012; Kacper Kowalik <email@example.com> xephem-3.7.3.ebuild,
+ Use XEphem license wrt #436630 by Ulrich Müller <firstname.lastname@example.org>