Re: GJD to HJD

[Michael Koppelman <lolife@bitstream.net>]

Hmm...  The numbers from Taichi Kato exactly match Lew Cook's spreadsheet.
  I get 0.001234 vs. their 0.001186 and 0.001791 vs. 0.001744. It's about a 
4 second difference in both cases. One would assume they are using the 
same algorithm. I'm fairly certain that I am not introducing any errors 
into the SLA routines but I cannot know for sure. For what I do, I think 4 
seconds is good enough, but it still leaves me a-wondering.

Cheers,
Michael Koppelman

On Friday, June 14, 2002, at 11:53  PM, Taichi Kato wrote:

> Re: GJD to HJD
>
>> This matches within 4 seconds of Lew Cook's spread sheet. He claims
>> accuracy near 3 seconds. Can anyone check this with something known to be
>> perfect?
>
>    I have done the same calculation.  I'm not sure whether the result
> is perfect, though...
>
>     Geo           Hel       Hel-Geo
> 52425.6907291 52425.692473 +0.001744
> 52431.6260590 52431.627245 +0.001186
>
>     Geo           Bary      Bary-Geo
> 52425.6907291 52425.692474 +0.001745
> 52431.6260590 52431.627245 +0.001186
>
>    BJD-HJD is incidentally almost zero in this case.  This is because
> Jupiter and Saturn are located almost exactly 90 deg from this trial
> position.  If one uses RA=6h Decl=0 instead, one obtains:
>
>     Geo           Hel         Bary       BJD-HJD
> 52425.6907291 52425.685701 52425.685667 -0.000034
> 52431.6260590 52431.620865 52431.620831 -0.000034
>
> Regards,
> Taichi Kato
>
>
>