[Kstars-devel] More star catalog issues

[Andrew Buck]

So I sent this message to the mailing list a couple days ago and
included the data on the NGC objects that I had worked out.
Unfortunately the message was too big and is awaiting moderation.  Here
is the same message without the data.  The data itself is at my website
again http://andrewbuck.homelinux.org/NGC

Moderators:  You can either delete the message with the data or pass it
on if you would like the data archived in the list.



Original message:
Wow, seems like there is a lot of interest on this subject, lots of
replies.  I will try to address all of the issues raised thus far in the
thread in this E-mail, as well as presenting my progress thus far.

> Before you go further, I should have asked you: have you
> used the Download New Data tool to get the improved Steinicke
> NGC/IC catalog?

I am getting my KStars data from ngcic.dat in my svn version of KStars
which has not had any updates performed on it.

> I was thinking you or I could write a (python|perl|ruby) script
> that goes line-by-line through our NGC catalog, and figures out
> if your parsed wikipedia data provides an improvement in either
> position or magnitude.  If so, the relevant field will be
> replaced.

I managed to get IRAF to do roughly what I wanted.  I wasn't able to do
any calculations with the RA and DEC because I don't understand the
format KStars is using (I think it might be "hhmmss" and "ddmmss" all
lumped together to form what looks like a 6 digit integer, is this
correct?).  Anyway, I was able to do a magnitude comparison.  I made a
table, listed below, which has magnitudes from Wiki and KStars as well
as a column of their differences.  There may be some issues with NGC's
that were listed multiple times in one catalog or the other (i.e. 72a,
72b, 72c, etc).  Im not sure exactly what happened with these entries
but I think the dataset will be useful regardless.  The data will
probably just have to be examined by hand and any changes made that way
as the formatting of the KStars data file is way beyond my
comprehension.  I think doing it by hand is the best way anyway because
we can then check out where Wikipedia got its magnitude from, etc, and
decide which one to ultimately use.

> It would be really great if we could get our hands on angular size
> and position angle data as well...ooh, it looks like simbad reports
> major/minor axis length and position angle.

If you can do a batch request and get me some raw data (flat text files,
column separated is best but I can try to work with whatever) I would be
happy to see what I can do.  The IRAF table tools are very powerful.

The Wikipedia data was not as complete as I expected, only having about
1600 NGC objects listed on the pages I grabbed the stuff from.  The list
that follows is the one explained above.  It is effectively the
intersection of the KStars catalog with the Wikipedia catalog.  It is
possible there were entries in Wikipedia that did not appear in the
KStars catalog, if this is the case then there will be no entry in this
list for that object.  I don't think this is very likely though as the
KStars catalog looks to be pretty complete.  The table is sorted by the
MAG_DIFF column.  Note, that there are differences in both the + an -
directions so entries at the top, and near the bottom before the INDEF
section are probably the most critical.  Also there may be entries in
the INDEF section that have mags on Wiki and not in KStars as an INDEF
in either field results in an INDEF in the DIFF field.

Again, let me know if there is anything further you would like to see
done, I enjoy the challenge.  :)

-Buck