PyEphem 是否使用完整的 VSOP87 和 ELP-2000/82 理论？
Does PyEphem use the complete VSOP87 and ELP-2000/82 theory?
PyEphem 是否使用完整的 VSOP87 行星理论和 ELP-2000/82 月球理论或简化版本（例如 Meeus 中给出的）？
根据 reference manual for XEphem (which pyephem is based on), "Credits" section:
The high precision planet positions were implemented for XEphem by
Michael Sternberg based on the
papers
- "Planetary Theories in rectangular and spherical variables: VSOP87 solution" by Bretagnon P., Francou G., in Astron. Astrophys. 202, 309
(1988), ftp://ftp.bdl.fr/pub/ephem/planets/vsop87/, and
- "Representation of planetary ephemerides by frequency analysis. Application to the five outer planets" by Chapront J., Astron.
Astrophys. Suppl. Ser. 109, 181 (1995), ftp://adc.gsfc.nasa.gov/\
pub/adc/archives/journal_tables/A+AS/109/181.
See the comments in chap25.h and vsop87.h for accuracy estimates.
The high precision Moon code was also implemented for XEphem by Mr.
Sternberg based on code supplied by Stephen L. Moshier
at
ftp://ftp.std.com/pub/astronomy/selenog.zip. Mr. Sternberg also
incorporated the algorithm for deltaT, based on code also provided by
Mr. Moshier. See the comments in deltat.c for full references. My
greatest thanks to Messrs. Sternberg and Moshier for their generous
and kind assistance in making XEphem a program of first-class
accuracy.
PyEphem 是否使用完整的 VSOP87 行星理论和 ELP-2000/82 月球理论或简化版本（例如 Meeus 中给出的）？
根据 reference manual for XEphem (which pyephem is based on), "Credits" section:
The high precision planet positions were implemented for XEphem by Michael Sternberg based on the papers
- "Planetary Theories in rectangular and spherical variables: VSOP87 solution" by Bretagnon P., Francou G., in Astron. Astrophys. 202, 309 (1988), ftp://ftp.bdl.fr/pub/ephem/planets/vsop87/, and
- "Representation of planetary ephemerides by frequency analysis. Application to the five outer planets" by Chapront J., Astron. Astrophys. Suppl. Ser. 109, 181 (1995), ftp://adc.gsfc.nasa.gov/\ pub/adc/archives/journal_tables/A+AS/109/181.
See the comments in chap25.h and vsop87.h for accuracy estimates.
The high precision Moon code was also implemented for XEphem by Mr. Sternberg based on code supplied by Stephen L. Moshier at ftp://ftp.std.com/pub/astronomy/selenog.zip. Mr. Sternberg also incorporated the algorithm for deltaT, based on code also provided by Mr. Moshier. See the comments in deltat.c for full references. My greatest thanks to Messrs. Sternberg and Moshier for their generous and kind assistance in making XEphem a program of first-class accuracy.