[Kstars-devel] Extending Hendry Draper numbers in Kstars

[M.S. Adityan]

Hi Alexander,

How would choosing arbitrary points on the image help? The idea is to
display the constellation image exactly as it is described in ancient maps
and atlases of the sky. This means suppose the head of Leo falls on Star X,
then that is how it should appear in KStars. This means the Star X acts as
an anchor for the head of Leo. Hence I cannot choose arbitrary anchor
points, but that anchor points should be real stars.

Yes, now I am trying to do this with RA/DEC coordinates of stars in the
J2000 system. I am also considering just using 2 points to simplify the
math, because I can always preserve the aspect ratio of the image, and
hence I would only require 2 anchor points in total to scale/rotate the
image. I am doing this for 1 constellation right now. Till then hopefully
we should figure out what requires to be done with those HD numbers which
are unknown to KStars. Either the HD number list in KStars is extended, or
I make a new list of anchor stars ALL of which are known to KStars. That
would be quite a lot of work, but will have to be done.

Thanks!

M.S.Adityan
Website: www.msadityan.com
https://www.linkedin.com/in/msadityan

On Tue, Jun 23, 2015 at 3:01 PM, Alexander Potashev <aspotashev at gmail.com>
wrote:

>
> On Jun 23, 2015 08:54, "M.S. Adityan" <msadityan at gmail.com> wrote:
> >
> > Another way to tackle this issue would be to use the HD numbers listed
> in clines.dat. Since KStars draws constellation boundary lines using these
> HD numbers only, I will not run into a problem. But again, it would be a
> lengthy process of figuring out the coordinates of the stars in the
> corresponding image.
>
> Hi,
>
> I agree, matching coordinates of constellation boundaries between kstars
> and stellarium would be a hard task. The boundaries in the two programs may
> be stored at a different level of detail, there may be no deterministic
> algorithms for this matching.
>
> Why do you need to add anchor stars into kstars? In order to calculate the
> transom transform parameters, three points should be enough, and these
> points don't need to be actual stars.
>
> For each of these three points you need to know their 2D coordinates in
> the image and their coordinates on the sphere (ascension and declination.)
> That's all — after you have 3 points per constellation, math comes into
> play.
>
> You can take whatever anchor points you like, for example 3 of the 4
> corners of a constellation image. I believe you can even discover some
> anchor points coded in the stellarium sources or data files.
>
> Happy hacking!
>
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