[Chaos-l] SkySafari

[Mark Montazer]

The Keplerian math is very simple and blazingly fast to compute. Getting
into the n-body stuff, you're talking about coding open differential
equation solvers (unless Apple's objective C library includes some), which
is a bit more complex. I wonder which ODE solver they went with or what
their acceptable error limit was.

Mark


On Tue, Feb 12, 2013 at 9:52 PM, Robert Nielsen <robertnielsen at nc.rr.com>wrote:

> I think a lot of you know that I use a planetarium program on my iPad (and
> iPhone) when observing ... including to control my telescope.  Well, the
> guys who developed it were annoyed that the position of the asteroid that
> will buzz Earth in a couple of days (2012 DA14) wasn't quite right ...
> because they were just using Kepler equations to compute the position ...
> so they went on an 80-hour coding marathon, consulted with JPL, and now
> have an more accurate n-body algorithm to calculate its position.
>
> Crazy, right?  All this on a smartphone! (or tablet in my case)
>
> The following link shows a video where one of the developers demonstrates
> the new feature.   What is amazing is that as the asteroid passes the
> Earth, the orbit is modified by Earth's gravity, and you can actually see
> it change in the app!
>
> http://www.youtube.com/watch?v=EOYCzfvnrbQ
>
> Robert
>
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