[Kstars-devel] VSOP data and the GPL

[Mike McGavin]

Hi KStars developers.

I hope I'm asking in the right place for this.  It seems like a
developer-related question, and kstars doesn't seem to have a
user-oriented mailing list.

I noticed that KStars includes some VSOP87 catalogue data in the
source tree.  I was hoping somebody could clarify the state of VSOP87
data and the GPL.

Lately I've been developing my own library that I've been releasing
under the GPL, which uses VSOP87 methods to calculate various
ephemerides.  I inherited some of the GPL'd code from an earlier
project that I forked, so re-licensing isn't really an option without
lots of complications.  It only occurred to me recently, when I went
to re-write the VSOP routines, that the VSOP87 catalogue data, which I
was re-inserting into the code in a slightly different format, might
not have been GPL-compatible.

I sent a query to the CDS service for astronomical catalogues, which
distributes the VSOP87 data online.  I've included the full response
from Sebastien Derriere at the CDS at the end of this post.  To
summarise, though, he said I was allowed to redistribute the data
freely, as long as I acknowledged the source, and as long as it was
*not* distributed under the GPL.  (Note that he's speaking more on
behalf of the CDS than the copyright holders, I think.)

I'm certainly not a GPL lawyer, but my understanding was that this
would make the VSOP87 data incompatible with the GPL, at least if
obtained via the CDS.  If it's incompatible, it could complicate
matters when it comes to distributing the VSOP87 data in GPL'd
software which (if I understand the correctly) would require
re-releasing the data under the GPL.


It's occurred to me that the data might easily have been released in a
GPL-compatible way through some other path that didn't involve the
CDS, such as directly from the copyright holders.  It's also occurred
to me that raw data such as that in the VSOP87 and other catalogues
might not be legally copyrightable in the way that the response to my
query implied, although I'm not personally qualified to judge this. 
I'm not aware of either of these possibilities, but I'm also not sure
where to start looking for them.

If anyone in the KStars team could clarify where the data was obtained
from, and how it works here, I'd really appreciate it.  I'm sure that
KStars isn't the only GPL'd project including VSOP87 data, but as
software that I use quite often, it's the first that comes to mind.


I also realise that if it's a problem for me, it might be a problem
for KStars.  I really hope there's a simple thing I've missed, and
that I'm not stirring up any potential problems by asking this.  At
the same time, though, I'm also struggling to figure out if I can
legally distribute the data within my own GPL software package.  If I
can't, I'd like to know.


Thanks.
Mike.


Here's the response I received.

=====

To: Mike McGavin <iizogii at gmail.com>
cc: francois at simbad.u-strasbg.fr
Subject: Re: Question about VSOP87 Catalogue Copyright Status
Date: Mon, 23 Jan 2006 17:07:57 +0100
From: "question at simbad" <question at simbad.u-strasbg.fr>

>
>Hello.  (I hope it's okay for me to post this query in English.)
>
>I'd like to query if the catalogue data provided in the CDS is in the
>public domain, or otherwise freely redistributable.
>
>I've found the CDS service to be a great service, and appreciate your
>effort in providing it.  I've recently reached a point, however, where
>I'd like to redistribute some of the data with a free software project
>that I'm working on.
>
>Specifically, I'd like to redistribute the data from the VSOP87
>catalogue (VI/81, detailed at
>http://cdsweb.u-strasbg.fr/cgi-bin/Cat?VI/81 ).
>
>I've seen many other software projects that distribute VSOP87 data,
>both freely and commercially, so I'm guessing that it's probably
>acceptable.  I can't seem to find any specific copyright notices or
>waivers around Simbad or the catalogue documentation, however.  It'd
>be helpful if you could please clarify the copyright state of the
>data.

  Dear Mike McGavin,

    Catalogues available at CDS contain scientific data distributed
for free, for a scientific usage.
    Companies including such data in their commercial products cannot
charge their clients for the data. Furthermore, users must be informed
of the origin of the data: this means an explicit reference to the service
provided by the CDS and also to the original author(s) of each catalogue.
Even for non-commercial use, the origin of the data and the CDS services
must be acknowledged in the documentation or copyright notice of the
software. The GPL licence should not apply to the data itself.
    You can find information relative to the original authors of the
data in the ReadMe file http://cdsweb.u-strasbg.fr/cgi-bin/Cat?VI/81
    Best regards,

    Sebastien Derriere, CDS
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