Denis Jul 6, 2012
On 06/07/2012 11:02 AM, Bill J Gray wrote:
> Hello all,
>
> OK, I've got it figured out... I should have puzzled it out right away;
> in hindsight, the problem is quite obvious to me.
>
> Short version: don't use the links to download critical, unusual, or
> distant objects. Update 'mpcorb.dat' instead. (I'll remove those three
> links in the next update.)
>
> Long version follows:
>
> Once upon a time, all of the "add-on" element lists were small, with at
> most a few hundred objects. But the "distant" list now contains 1717 objects;
> the "unusuals" list contains 9701 objects; and the "critical list" contains
> 1691 objects.
>
> This raises a dilemma. I _could_ just revise Guide to handle this sort
> of thing. But it would be wrong to just bump up the limit. It puts
> thousands of objects into the "added comets/asteroids" file; if you go
> to Extras... Asteroid/Comet Options... Edit Comet/Asteroid Data, you
> get an immense list of objects. And Guide's efforts to merge in these
> MPC update files with existing asteroid data have never been completely
> successful.
>
> To quote from the dialog wherein one can download asteroid data:
>
> "...Use of the following links [to update distant, critical-list,
> and unusual objects] is not really recommended. The objects in question
> already have well-determined orbits, and the latest MPC data will
> represent only a small improvement. By far the best way to update
> asteroids is to use MPCORB. This allows you to update Guide's asteroid
> data completely. The only downside is that MPCORB is about 30 MBytes
> in compressed form, a bit large for those with dial-up modems."
>
> That last issue is getting to be less of a problem; for most of us,
> a 30 MByte download is peanuts. The next update will remove the ability
> to use those three links; we'll go from "updating" asteroids to just
> replacing the entire asteroid dataset with a new MPCORB.DAT.
>
> (Ideally, I'd do the same thing with comets. Sadly, there is no
> way to get a complete comet database; MPC just supplies "currently
> observable comets", which have to be merged with older comets in order
> to have a complete list of comets.)
>
> -- Bill
>
>
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