Re: asteroid (70401) davidbishop - check residuals

Néstor D. Díaz Feb 5, 2013

Aha, good trick! Typical of programmers (I am one)... ;)
Thanks for your response.

> I've some ideas in mind (which you may have seen discussed on MPML) for
> use of the BC-405 ephemerides, to handle 300 asteroids. For that to work without
> slowing things down, Find_Orb will have to be pretty intelligent about figuring out
> when close approaches occur, and that data would be shared with the user. (Who should
> then share it with people doing asteroid mass determinations!)
And also from MPML:
>The main problem will be having
>the software figure out which of those 300 actually come close enough to
>matter, without going through the tremendous computational effort of
>computing all 300 all the time.

If I understand what you want to do: What do you think about generate a file with pre-calculated approaches of these 300 objects for a limited range of years (or different files with different ranges), and then Find_orb can look on this file(s) to know when to use one of these objects as perturbers.
Could this method be less CPU-time consuming?
Yeah, I know, this will generate a huge file (or several large files), but surely finding an object in question linked to one of these 300 objects in pre-calculated data is likely to be much faster than calculating all time.
If the size of the file(s) is a problem, obviously this could be optional.

Néstor D. Díaz
Rosario, Argentina

--- In find_orb@yahoogroups.com, Bill Gray wrote:
>
> Hi Nestor,
>
> > Bill, one question:
> >> (70401) Davidbishop passed within about 400000 km of Pallas on 1982 Feb 27.
> > How did you get to this? Is there an utility to look for asteroids approaches between them,
> > or something like that? (Sorry if this is a silly question...)
>
> Well... I have to admit, I sort of cheated here.
>
> I knew there must have been a close approach, since things improved so drastically
> with asteroids turned on. I didn't really know when.
>
> Find_Orb can compute ephemerides centered on planets. If I'd wondered about, say, a
> close approach to Mars, I could have run a Mars-centered ephemeris (MPC code "Mar") and
> seen it right away. But at least as yet, you can't make a Pallas-centered ephemeris.
>
> So I edited the code and added a debug statement: if an object came within .1 AU
> of Ceres, Pallas, or Vesta, the time, distance, and object were logged. It was
> a pretty short log; it wasn't hard to find the culprit.
>
> However, it's not a very "general" method. It also works only for the Big Three
> asteroids. I've some ideas in mind (which you may have seen discussed on MPML) for
> use of the BC-405 ephemerides, to handle 300 asteroids. For that to work without
> slowing things down, Find_Orb will have to be pretty intelligent about figuring out
> when close approaches occur, and that data would be shared with the user. (Who should
> then share it with people doing asteroid mass determinations!)
>
> -- Bill
>