Hi John,
I use the ucac3.idf file exactly as it is downloaded from ProjectPluto web page.
I also tryied to switch to the English version with the same results.
Unfortunately I don't have the Spanish language installed.
I'm an "asteroid peep" as you wrote but I would prefer "observer" instaed.
I do not think to be "pretty fetishistic about always using the latest astrometric catalogue". I just use UCAC3 when I think it is useful in order to improve the quality of my astrometry, as it exists, and I think also that all guys doing astrometry are quite happy when they can improve the quality of their job using the latest astrometric catalogue even if it is not perfect.
Tomorrow I will go for ten days fishing trouts, I hope when I will be back to be able to solve the problem, maybe Bill, or someone else, will do it before.
Stefano.

--- In guide-user@yahoogroups.com, substellar@... wrote:
>
> "It seems that UCAC3 at level 8 or higher "deletes" the GSC, Tycho, Hipparcos
> stars."
>
> Nope, what happens is when you start guide it makes a list of all the data files for the TDFs and the names of the TDFs using those data files, this data file lives in the Guide directory and is called TDF_LIST.DAT (imaginatively enough).
>
> This is refreshed every time Guide is launched, for after all the user may have removed or added a TDF at some point, or a dataset name, or changed one, and this automatic refresh is better than having to tweak guide.dat or something like that every time a small change is made in Guide. It looks for the TDFs (including language variants when that's relevant) in the Guide directory and it seems it looks at the 'file' lines therein to link them to the data they plot (I'm guessing there).
>
> It looks to be alphabetically sorted.
>
> So, the last line on your tdf_list.dat will very likely be ucac3.txt and ucac3.idf. Mine has some extra, like xmm and yb6, but most people will probably have ucac3 as the last on the list, if they have ucac3. You should have two, one for vizier and one for the hard disk version.
>
> Many people may have noticed when plotting wide fields that Guide plots stuff in 'waves' a layer at a time. That is as each tdf is plotted.
>
> Now, I can't remember if Guide tends to plot the TDFs in reverse order from tdf_list.dat, but it certainly can plot the TDF objects _before_ it plots the "internal" catalogues. And the internal catalogues are GSC, USNO A2.0 (which isn't done by a tdf if taken from hard disk, but is internal in the Guide program) Tycho2 and Hipparcos.
>
> So if ucac3.idf is broken, and either stops or kills the plotting at smaller fields than level 8 after the ucac3 stars are drawn (and are all the ucac3 stars drawn before it stops?), then these stars in the next catalogues will not get plotted. It's got stuck, so to speak. It is not that they are 'deleted', it is that they are not drawn in the first place, as that part of the program is never reached. Possibly (all guesswork).
>
> The novel things ucac3.idf are using are the command volatile (which has been around for a while and is used in other TDFs) and some new commands dealing with ra and dec proper motion, as it uses UCAC3 proper motion information to decide where plot the stars, that is it is involved in the plotting of the stars. I don't know much about these commands, I don't use them, I don't correct plots for proper motion, I like to see all catalogues plotted at epoch of observation, as I use Guide for researching stuff, not for making charts or observing. Photo is a command that is not new, but can cause problems if some typographic error gets in there (as I said, errors in photo can make my old version of Guide instantly crash when it tries to plot stars).
>
> My personal suspiscion is that because you seem to have no problems with ucac3 from vizier, as you have said, but do have problems with ucac3 from hard disk, then unless there is some subtle difference in the plotting commands for those two .idf files that do those two separate tasks, but using the same sort of ucac3 data (so they should both plot things the same way), then if one works, both should work. If there is a difference in the two .idf files, that might be it. If there isn't, then I suspect some simple spelling or typographic error in the hard disk .idf. As I say, try the .tdf and see what happens.
>
> I've not seen anyone else mention problems with ucac3 from hard disk either, and I know some others like the idea of grabbing always the very latest big astrometric catalogue and copying it to hard disk, especially the asteroid peeps, they're pretty fetishistic about always using the latest astrometric catalogue, irrespective of whether it's any real improvement or not.
>
> John
>