[Kstars-devel] KStars and custom catalog loading

[Jason Harris]

Hi Mike,

Thanks for your important feedback.  The biggest problem with custom 
catalogs is that it's a relatively untested feature.

Can you send me your parsed Tycho-2 catalog fragment?  I'd like to try 
adding it as a custom catalog myself.

One workaround that we can talk about is for you to add the Tycho 
catalog as a supplement to the current Hipparcos star catalog, rather 
than adding it as a separate custom catalog.  This will involve some 
very simple modification of the code, and some reformatting of the 
catalog (you'll also need to split your catalog files into files 
containing 1000 lines each; we do this for faster startup, as each file 
is read into a list of strings, and these strings are processed, rather 
than reading line-by-line while processing).  Let me know if you are 
interested in this option.

As you may know, we aren't actively developing 3.5 anymore, so any 
speedups we implement will have to wait for 4.0 (unless they can be 
considered bugfixes of the existing codebase, which is somewhat subjective).

regards,
Jason

Mike McGavin wrote:
> Hello.
> 
> I was wondering if I could ask what the state is of KStars' handling
> of custom catalogues, and are there any particular recommendations for
> getting custom catalogs to load efficiently?
> 
> I've been experimenting with trying to load the Tycho-2 catalogue in
> kstars 3.5.2 (the most recent build in Debian).  I like star hopping
> to faint objects with my telescope, and I'm quite keen to get stars
> down to about 12th or 13th magnitude, when zoomed in to a small enough
> area, at least.
> 
> I've had a few problems, though, mostly with kstars apparently not
> being able to handle the size of the input data.  The entire Tycho-2
> comes as about 500 MB uncompressed, even though most of the fields can
> be filtered out during import.  I gave up on the Import Catalog
> feature, because I couldn't get it to recognise the data format.  Even
> so, it didn't seem as if it wasn't quite designed to cope with
> massively sized cataloges, and I managed to crash it several times
> without too much trouble.
> 
> I then wrote a short Python script to manually convert about 1/75th of
> the Tycho2 catalogue (~35000 stars) to the kstars custom catalog
> format.  Kstars is able to load this, but the startup time slows to a
> crawl at the 'loading custom catalogs' phase.  Just now it's taken 11
> minutes to load compared with a matter of seconds.
> 
> I'm guessing this slow-down is because custom catalogs aren't indexed
> in the same way as kstars' internal catalogs, although you guys would
> know better than I would.  Also, once kstars actually does finish
> loading, I haven't been able to confirm that the additional stars are
> even being displayed.  I've searched the areas of sky concerned, and
> can only find relatively bright stars that I think are probably still
> from Hipparcos.
> 
> Is there any alternative way to load data, and maybe index it, that
> might help kstars access it more directly and efficiently?  If there's
> a consistent format and/or index format somewhere, I might just be
> able to write another script to convert the catalogs I'd like so that
> kstars can use them effectively.  If extra catalogs simply aren't well
> supported at this time, that's okay.  I'm just keen to know if there
> are any possible workaround that I might try.
> 
> 
> Thanks.
> Mike.
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