[Kstars-devel] Star coordinate inaccuracy -- Hipparcos Epoch bug

[Akarsh Simha]

> I think the error derives from old stars.dat, that has been somehow
> "compiled" into data kstars is using now. I already provided a copy
> of stars.dat with coordinates corrected using novas-c library
> (http://aa.usno.navy.mil/software/novas/novas_c/novasc_info.
> I think this corrected file has been committed into kstars current
> sources, the only problem is that it isn't referenced anymore in any
> of the other source files...

Wow. That is odd. I'll look for it. Any recollection of what it is
called? I designed the star catalog binary files, so it might in fact
be good for me to set up the star catalog machinery on my computer and
clean it up with sufficient READMEs etc. In the process, I'll
incorporate these changes.

> >However I can also find bright stars that are unaffected. In any case,
> >it would be good to have a reliable list of stars' coordinates, that I
> >can use to patch the star catalogs and release them.
> 
> Yes, I noticed that too. I think that depends on sky position and
> little proper motion. In the corrected stars.dat those stars haven't
> moved a lot, as expected.

Ah, okay.

> >OTOH, I noticed that from your mail sometime in 2011, you point out
> >that deep-sky catalogs are problematic too.
> 
> That was when I first noticed coordinates problem, and I blamed
> (incorrectly) deep sky catalog: the telescope I'm using at the local
> observatory has relative encoders, so we point at a bright star,
> sync and and then move to desired object. When pointing at faint
> objects, I noticed the accuracy of slew was poor, but the errors in
> bright stars catalog explain perfectly well the problem. :)

Okay, that makes sense.

> Sadly, due to this lack of accuracy, we had to switch kstars in
> favor of skychart, which by the way has a sound support for custom
> and online catalogs that I've started to fall in love with.

Wow. I didn't know Skychart did custom and online catalogs. What
exactly do you mean by "Online catalogs"? It's been quite a long while
since I used Cartes (I used it on Windows, version 2.8 or
something). I also didn't know Skychart did observatory control.

In KStars, I've been considering being able to interface with SIMBAD
and import objects from SIMBAD into the database.

Regards
Akarsh