arika

Coordinate frames, reference transforms, epochs, and celestial body ephemerides for orbital mechanics. The name 「在処」(arika) means “the whereabouts of a thing” — coordinate transformations express the same position in different reference frames, telling you where something is from different points of view.

Provides typed coordinate frames (ECI, ECEF, ITRS, TIRS, CIRS, GCRS, topocentric), the IAU 2006/2000A CIO-based Earth rotation model, geodetic conversions against WGS84, time-scale-tagged Epoch<S>, and Sun/Moon/planet ephemerides.