[AZ-Observing] Re: Asteroid 2012 DA14 and SkySafari
- From: Dan Heim <dan@xxxxxxxxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Tue, 12 Feb 2013 11:43:23 -0700
Well all I have for now is this crude chart I put together from the
latest ephemeris for DA14: http://www.dfacaz.org/maps/DA14-PLOT.jpg
I was hoping to catch it as it passes Kappa Draconis about an hour after
sunset on the 15th. It'll only be about 20° elevation, but I have a
great clear view to the NNE from my hilltop here in New River. If you
could post a more accurate chart, it would most appreciated. Haven't
been able to find much online, and I don't have SkySafari.
BTW, had to laugh about your comment on the Runge-Kutta method of
solution. I do believe my physics prof said exactly the same thing ...
and he was right. Other than on the final exam, I have never used it
since. :)
Dan Heim
On 2/12/2013 11:21 AM, Tom Polakis wrote:
> This is only sort of related to observing in Arizona, so delete if you're not
> interested.
>
> People who use desktop and tablet planetarium software/apps have been
> noticing that the predicted position of Friday's close-approaching asteroid
> is many tens of degrees off. The error is due to most software neglecting
> the perturbation of the orbit due to Earth's gravity.
>
> The authors of the SkySafari for iOS decided to do something about it. The
> latest release of SkySafari nails the position within arcseconds. The
> method, which includes some high math and understanding of orbital mechanics,
> is explained below by co-author Tim Debenedictis. I copied and pasted his
> message from the southern-stars mailing list.
>
> The mention of "4th order Runge-Kutta" made me flash back to my engineering
> numerical methods class, in which the professor interrupted his lecture to
> tell us that we'll never use this stuff. Thankfully, in my case, he was
> right.
>
> Tom
>
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