Re: [guide-user] JPL and INPOP ephemerides

Bill J Gray Nov 12, 2012

Hi Dario,

> 1) Guide can manage the latest jpl ephemerides DE422 for the planets position.
> The moon librations and nutation data are also calculated?

They are, but not using JPL ephemerides. Nutations are computed using the IAU series.
The moon's orientation is computed using the COSPAR model for the moon's orientation.

> 2) Could be possible to add the possibility for manage the binary data files
> compatible with the JPL DExxx ephemeris file format - INPOP10b?
> You can find the data in:

Guide will do this. You can set it to use INPOP ephemerides in the same manner
as setting it to use any JPL ephemeris file, as described at

One does have to use the "binary files compatible with the JPL DExxx ephemeris
file format"; Guide doesn't use the raw INPOP files.

(Note that if you're still running Guide 8, you will need current software to
make use of INPOP. INPOP ephemerides are _almost_ in the same format as JPL ones.
But they are aligned to noon rather than midnight. That required a small change,
made in March 2011.)

> 3) Could be possible to solve the compatibility for all the future upgrades using
> the header and constant values written at the beginning of the DExxx/INPOP binary files?

Already done. None of the DE versions has required changes to Guide. INPOP
wouldn't have, either, except that it hadn't occurred to me that there might be
ephemerides aligned to noon.

-- Bill