Version 2.6 is available upstream. Please consider updating! It seems that version 2.6 is available upstream, while the latest version in the Gentoo tree is 2.5. You think this warning is false? Read more about it here.
CCfits is an object oriented interface to the cfitsio library. It is
designed to make the capabilities of cfitsio available to
programmers working in C++. It is written in ANSI C++ and
implemented using the C++ Standard Library with namespaces,
exception handling, and member template functions.