Whole-grid IONEX vertical-TEC samples.
Map epochs are split Julian dates with time-scale tags. Latitude and longitude
axes are degrees, shell and base radii are kilometers, and TEC/RMS grids are
TECU with indexing [map][latitude][longitude].
Summary
Types
@type epoch() :: Sidereon.GNSS.Ionosphere.TecSample.epoch()
Epoch as %{time_scale:, jd_whole:, jd_fraction:}.