Re: GJD to HJD

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

Re: GJD to HJD

> If you look up the planet's orbital elements at 
> http://ssd.jpl.nasa.gov/elem_planets.html you find the notice below.
> I think what it is saying is that planets don't move in Keplerian
> orbits.  but if you asume they do (as does the SLA routine) you
> should expect up to 25" of error.  The resultant jd -> HJD conversion
> error will depend on the time of year and direction you are looking. 

   My calculation of BJD was indeed numerically integrated DE 200-based
(I used the numerical integration code developed by Novas-san; now the JPL
ephemeris has a newer version, but the difference is negligible).
My HJD calculation was based on Newcomb expansion, a more traditional
form of planetary ephemerides.

Regards,
Taichi Kato