WOW! What a speed up in computation time!!! I added the line
pointing the enviroment variable to the JPL data in my Guide8 sub-
directory and now the orbit computations really fly, even with all
planetary perturbations turned on. Thanks a million for that tip
Bill.

Does your INTEGRAT function with Guide8 use the same JPL data to
speed up the time it takes to update asteroid elements to a
different epoch? If so, how do I setup that one to work?

--- In guide-user@yahoogroups.com, Bill J Gray <pluto@p...> wrote:
> Hi John,
>
> Regarding that five-minute run with the entire dataset: you
> should probably set up Find_Orb to make use of JPL DE ephemerides.
> Doing that should bring you down to the ballpark of ten seconds.
> This is described a bit at
>
> http://www.projectpluto.com/find_orb.htm#de_eph
>
> Use of the pre-1990 observations will not (in general) be
> very useful, simply because their accuracy usually isn't as
> good as more recent astrometry using modern catalogs and CCDs.
>
> Find_Orb doesn't do any automated selection of observations.
> (At least, not yet.) For this object, all I did was to select
> the observations from the three observatories mentioned in my
> previous post: (673) Table Mountain, (689) Flagstaff, and
> (950) La Palma. These observatories all are deliberately going
> after highly precise astrometry, with observations reduced using
> Tycho-2 or UCAC2. There are probably some others (for example,
> Gordon Garradd at (422) Loomberah has gotten some excellent
results),
> but not many, and I don't know who they might be. Perhaps Jan
> Manek or Rob Robinson or Steve Preston could comment?
>
> As you noted, if you click on Herget, Find_Orb doesn't use
> all the data; it just selects a subsection containing a few
> hundred days' worth of data. That's because the method of Herget
> doesn't work well on longer arcs (details are given on the Find_Orb
> page,
>
> http://www.projectpluto.com/find_orb.htm
>
> The methods of Vaisala and Gauss are similarly limited. All of
> these are really intended just to get an initial orbit (and in the
> case of the method of Herget, to refine that orbit a little).
Once
> you have a good initial solution, the "full step" (least squares)
> method can be used, without running into such limitations... a
> full explanation is quite lengthy; it's given at the above page,
> and truly gung-ho orbit computers would probably say I've barely
> scratched the surface of this topic.
>
> -- Bill