[Kstars-devel] Predicting conjunctions

[Jan Kotek]

Hi,

Sounds like good example for derivations.

1) function for calculating position of planet (already in KStars)
2) function which returns distance of two planets
double getDistance(double time)
3) calculate minimum of this function for given time (thats conjunction)

You can use interval division to find minimum...

This works for any orbit which have algorithm for position (planets,
comets, asteroid...).

Regards,

Jan Kotek
http://kotek.net/opencoeli

On 3/12/08, Akarsh Simha <akarshsimha at gmail.com> wrote:
> Hi
>
>
>  > How about using KStars to march forward (and back) in time and write out
>  > the conjunctions to a file?   Even if it takes a few days (or weeks?),
>  > it is done.  Distribute the data file as part of KStars.
>
>
> That is a good idea too... but I was thinking on the lines of being
>  able to predict close approaches between any two objects - not
>  necessarily planets. For example, the user selects a comet and some
>  Messier galaxy and asks when they will be less than 1 degree apart,
>  and we compute the time of the next such occurance.
>
>  @Jason:
>  I don't know if there's a standard definition for "close
>  conjunction". I thought we could ask the user to input the minimum
>  separation he wants (for instance, if I want to see both of them
>  simultaneously in my telescope, I can use the FOV of my telescope)
>
>  Could you tell me where I can find this sinusoidal series expansion?
>  Does it work for any orbits? IMO, it would be very helpful if it could
>  be extended to comets as well. What are the .vsop files that we have
>  for planets?
>
>  I think my earlier approach is fundamentally wrong because I think it
>  is the geocentric longitude that needs to be equal and not the
>  heliocentric longitude. I tried to grossly approximate the former
>  condition with the latter.
>
>  Regards
>
> Akarsh.
>
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