[Kstars-devel] Prakash's KSalmanach

[Khudyakov Alexey]

On Saturday 23 May 2009 22:01:20 Akarsh Simha wrote:
> > This way calculated twilights are longer than real. Moreover solution
> > always exist even if sun never goes below 6/12/18 degrees.
>
> That's right. I suggested the linear interpolation, figuring that the
> error will be within 1 minute of time. I requested Prakash to indicate
> that in the comments. I don't know if he's done that.
>
Hmm... for what latitudes? In high latitudes answer will be anything but 
accurate. Border case: Sun's low transit is at about -3 degrees. There is only 
civil twilight, although linear extrapolation will give answer for both 
nautical and astronomical twilights.

> > Right way to do this is to find when Sun goes above/below -6/12/18 deg.
> > as done in SkyObject::riseSetTime. However it will require a lot of
> > changes to that function.
>
> Hmm... Maybe we should correct that and make it as accurate as KStars
> claims to be. Prakash, would you want to do that? Some
> code-duplication might be okay. If we really want to avoid code
> duplication, I guess we should have a method to compute the fine
> position given an approximate position.
>
I think it's better be implemented in SkyObject class. This would require 
extensive refactoring. And duplicate code always could be removed.