Alan W Harris 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