Differences in parallax calculations

[rpoleski]

@jluastro pointed to me differences in parallax calculations between MM and BAGLE. First, could you remind me if ~10^-4 was an absolute or a relative difference in magnification? Second, in MM we use astropy.coordinates.get_body_barycentric() called with body='earth', time=Time(times, format='jd', scale='tdb')). You can set the ephemeris using solar_system_ephemeris() before calling MM code. Please let me know if that makes differences smaller.