boost::geometry::cs::spherical_equatorial
cs.hpp
typename DegreeOrRadian
core_detail::coordinate_system_units< DegreeOrRadian >::units typedef core_detail::coordinate_system_units< DegreeOrRadian >::units boost::geometry::cs::spherical_equatorial< DegreeOrRadian >::units units

Spherical equatorial coordinate system, in degree or in radian.

This one resembles the geographic coordinate system, and has latitude up from zero at the equator, to 90 at the pole (opposite to the spherical(polar) coordinate system). Used in astronomy and in GIS (but there is also the geographic)

http://en.wikipedia.org/wiki/Spherical_coordinates

- boost::geometry::cs::spherical_equatorial
  units