Hi Javier,

> But it's not Kstars who is involved here, _any_ program must be able to use
> the data or else it cannot be included in Debian. 

...and in another message:
> This is an issue, if the data can _only_ be distributed with a GPL program
> then it's not free.

Look again at what Laurent said in the second reply.  Any program, including a 
non-GPL, commercial program is welcome to use a CDS catalog, as long as they 
don't charge their customers for the data files, and as long as credit for 
the data is given to CDS and the catalog's original author.  I can think of 
no astronomy program in the history of computing that ever charged its 
customers for catalog files.  So if you must place KStars in non-free because 
of a hypothetical situation that has never occurred and will almost certainly 
never occur, then so be it, I suppose.

I mean, think about the situation you are proposing:  Some company harvests 
the SAO star catalog from KStars, which they obtained as part of Debian.  
Never mind that they would almost certainly get the catalog directly from the 
CDS website; for whatever reason, they like our version better.  Now, this 
company writes a non-GPL, commercial astronomy program that uses a derivative 
of the KStars SAO data file (which definitely *is* GPL'd).  

So far, neither we nor the CDS have any problem with what the company has 
done, as long as they distribute at least the SAO data file (derived from the 
KStars version) under the GPL.  Okay?  Now the *only* way they can get in 
trouble with the CDS is if they explicitly charge their customers for access 
to the *one* part of their program that is GPL'd!  If they tried this, the 
first person to pay for the catalog could just put it up on a website for 
free download, and the company couldn't do anything about it.  In other 
words, it would be an extremely foolish way to sell an astronomy program.

Still, let's even grant the possibility that we have this moronic company 
trying to sell access to a GPL'd data file, versions of which are available 
for free from multiple other sources.  The CDS finds out about it and gets 
pissed.  Whom do they sue?  The company which broke the (unpublished) CDS 
policy of not charging for data access?  Nope.  The GPL'd astronomy program 
from which the company derived their SAO catalog? Nope.  Get this: they sue 
Debian! the linux distribution that the company happened to use as a 
middleman when acquiring the GPL'd data file in question.  I don't know, 
Javier, I appreciate that you are trying to be extremely careful here, but 
seriously, this is totally absurd.

> Notice that if the catalogue would be explicitly in the public domain none
> of this would be an issue. I believe this is the case for the Hipparcos
> catalogue (which spacechart uses). 

That's news to me.  In my rather exhaustive search (ok, exhausting anyway :) 
of the web, I looked for license information for both the SAO catalog and the 
Hipparcos catalog.  I found exaclty the same answer in both cases: absolutely 
nothing.  And Laurent tells me that the two are released under the same terms 
(at least if you get them from the CDS).

The one star catalog that I know for sure is in the public domain is the 
Hubble Guide Star catalog.  I am willing to look into migrating to the HGSC 
if we can't resolve the issues with CDS catalogs; at this point I am just 
amazed how many different ways the phrase "yes you can use our catalogs" can 
be interpreted as "no we can't use their catalogs" :)

best regards,
Jason
-- 
KStars:  A K Desktop Planetarium
http://edu.kde.org/kstars
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