Re: [find_orb] Chelyabinsk Meteorite

Bill Gray May 24, 2013

Hi Glen,

> As I understand it, the authors of that paper used NOVAS to calculate
> the orbit. Couldn't they just as well have used Find_Orb?

Yes. Very shortly after the impact, I got an inquiry about this
from someone hoping the object might be found on recent survey images.
That resulted in my posting this pseudo-MPEC, with a (G96)-centric
ephemeris to see if any of the southwestern US folks might have
gotten the object on the way in :

http://www.projectpluto.com/temp/chelyab.htm

You'll notice that this was computed on the day of the impact, and
was intended just to get a rough idea (enough to say, "Sorry, no,
there aren't going to be any precovery images.") I'm sure Esko
Lyytinen and/or Rob Matson and/or somebody else got more and better
data after that. But even the very approximate data were enough to
make it clear: this object came from too low an elongation to be
spotted on its way in.

I will not be surprised if it's a long time before another case
occurs of an impactor observed before impact. It _has_ happened
once (2008 TC3), and I keep an eye on NEOCP for objects that might
do this. (The key sign is that the ephemerides show virtually no
motion, then suddenly show _lots_ of motion. That was what clued
me in for 2008 TC3.) But I'm not really optimistic.

-- Bill