问题
The documentation says that if pyEpehm is given a TLE and a time it will return the following. However, I'm having no luck converting the returned 'sublat' and 'sublon' to ECEF XYZ and back to LLA coordinates to verify. When I convert back the longitude is preserved but the latitude is off by about ~20 degrees for different tests. I am using functions that are verified with GPS ephemeris and I am very confident that the LLA to ECEF and back works for those parameters. Something else is going on here. Does anybody know if 'sublat' and 'sublon' are given in geocentric??
On artificial satellites, also sets: Geographic point beneath satellite: sublat — Latitude (+N) sublong — Longitude (+E) elevation — Height above sea level (m) range — Distance from observer to satellite (m)
回答1:
They're in geocentric coordinates.
来源：https://stackoverflow.com/questions/8548628/is-pyephem-sublat-and-sublong-given-in-geocentric-or-geodetic